Mount popocatepetl mexico cannabis seeds

Mount popocatepetl mexico cannabis seeds

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The plant kingdom and hallucinogens (part II)

The plant kingdom and hallucinogens (part II)

Ph.D. F.L.S. Richard Evans SCHULTES
Curator of Economic Botany and Executive Director,Botanical Museum of Harvard University, Cambridge, Massachusetts, U.S.A.

Amaryllis family

Amongst the Kung tribe of Bushmen in Dobe, Botswana, this bulbous perennial, known locally as kwashi, is said to have psychoactive properties. When the bulb is rubbed on an incision made on the head of a tribesman, visual hallucinations are said to be induced. Nothing more is known of this curious custom.

Pancraetium, a genus of some 15 species in the warmer parts mainly of tropical Asia and Africa, possesses powerfully toxic principles, including alkaloids. A number of species find use amongst primitive peoples as emetics. Pancraetium maritimum and other species are cardiac poisons, and P. zeylanicum has been reported to cause death through paralysis of the central nervous system. In India, Pancraetium triflorum may sometimes appear in markets as an adulterant of the medicinal Urginea. In Shari-Chad, West Tropical Africa, Pancraetium trianthum, reputedly very toxic, is commonly planted at shrines.

Ginger family

Vague information has indicated that possibly a member of the Ginger family, Kaempferia Galanga, may be employed by natives in several parts of New Guinea as an hallucinogen.

The rhizome of Kaempferia Galanga is the source of a condiment known as galanga, highly valued in tropical Asia. The rhizome, mixed with oils, is employed in the Philippines as a cicatrizant and applied to boils and furuncles to bring them to a head. Other species are likewise prized as condiments and medicinally as agents effectively hastening the healing of wounds and burns.

Almost nothing is known about the psychotomimetic use of this plant, and no investigation of a possible narcotic chemical constituent has apparently been made.

Mulberry family

Undoubtedly one of the oldest known and certainly to-day the most widely spread hallucinogenic plant is Cannabis sativa. Despite its great age as one of man’s principal narcotics and its use by millions in many cultures the world around, Cannabis is characterized more by what we do not know about it than what we know. Our lack of knowledge about Cannabis and its use as an intoxicant not only provides an obstacle to an understanding of moral, legal, sociological and economic phases of its importance to the cultures where its utilization has become established but even many scientific aspects – botanical, chemical, pharmacological, medical and public health – are fraught with uncertainties and contradictions.

Even in what should be the basic study of this plant – the botanical field – we find disagreement as to its classification. Many taxonomists place the monotypic genus Cannabis in the family Moraceae, while others set it aside, together with the hops plant, in a distinct family: Cannabaceae.

One of the most ancient of man’s cultigens , Cannabis sativa has been a triple purpose plant: a source of hemp fibre, of a seed oil and of a narcotic. This rank, weedy annual that commonly grows to a height of 15 feet is native probably to Central Asia but has escaped from cultivation in many parts of the world and grows spontaneously. Flourishing especially in disturbed, nitrogen-rich wastelands near human habitation, it occurs widely in temperate and hot drier areas of both hemispheres and seems to be unhappy only in the coldest zones and the hottest humid tropics.

Hemp was reported in a Chinese document 8,500 years ago, and the Assyrians used the plant in the ninth century B.C. in the form of an incense. The Sanskrit Zend-Avesta first menti0ned its intoxicating resin in 600 B.C. Herodotus wrote that the Scythians burned its seeds to produce a narcotic smoke. In Thebes, it was made into a drink with opium-like properties. Galen reported general use of hemp in cakes which, if eaten to excess, had narcotic properties. In thirteenth century Asia Minor, the hashishins were political murderers who, excited to their nefarious work by taking large doses of hashish, would carry out murder for pay; from this Arabic term comes the word assassin.

Although the narcotic use of Cannabis harks back thousands of years in India, the Near East, parts of Africa and other areas of the Old World, its spread to nearly all inhabited parts of the globe has allowed its employment as an inebriant recently to increase in sophisticated societies, especially in urban areas, and to lead to major problems and dilemmas to European and American authorities. Studies in depth of its utilization in less developed societies should shed much light on some of the problems resulting from its use and abuse in more advanced communities.

Methods of using Cannabis vary widely. In the New World, marihuana or, in Brazil, maconha – the dried, crushed flowering tops are leaves – are smoked, usually mixed with tobacco, in cigarettes. In parts of primitive Africa, Cannabis fulfills an important role in religion and magic. In southern Africa, it is called dagga, a term sometimes also applied with a qualifying adjective to sundry species of the labiate genus Leonotis, several species the leaves of which are perhaps feebly narcotic when smoked. In Morocco, where the use of Cannabis is common, the vernacular name is kif. Hashish, the resin from pistillate flowers, is eaten by millions, especially in Moslem areas of North Africa and the Near East.

It is apparently in India where Cannabis assumes an extraordinary religious significance in certain cults and where, as a result, man has selected “races” characterized by high concentrations of tetrahydrocannabinol. The ancient Indian Atharva-Veda called the drug a “liberator of sin” and “heavenly guide” and the plant is still held sacred in many temples.

Indians commonly employ narcotically three Cannabis preparations. Bhang, the weakest, consists of the dried plant gathered green, powdered and made into a drink with water or milk, or with sugar and spices, into candies called majun; opium and Datura are said sometimes to be added. Ganjah, usually smoked with tobacco but sometimes eaten or drunk as an infusion, consists of dried pistillate tops with exuded resin carefully gathered from cultivated or escaped “races” notably rich in tetrahydrocannabinol. Charas, pure resin removed from leaves and stems also from especially cultivated, strongly narcotic “races”, is normally smoked but it may be eaten mixed with spices. Cannabis supplies the drug of the poor in India, where, in addition to its religious use, it is highly valued in folk medicine and as an aphrodisiac; and, hedonistically, as an euphoric narcotic, especially in activities requiring endurance or physical effort.

Although the marked increase in smoking marihuana in the United States poses a variety of problems, much of the drug illicitly used at the present time in the country is weak in the narcotic principles, since it consists not of pure resin but of crushed leaves, twigs and tops of plants notably low in tetrahydrocannabinol. These plants grow spontaneously, spread mainly from hemp formerly cultivated in plantations for fibre production, at one time a major agricultural industry in North America. Marihuana smuggled into the country from Mexico or other tropical areas represents usually a stronger and potentially more troublesome narcotic.

Over the millenia, man has selected, subconsciously at first, consciously in more recent times, “races” or “strains” of this cultigen with desirable characteristics for the purposes at hand: some for longer, stronger fibre; some for higher oil content; some for greater narcotic potency. Selection for increased narcotic activity has been especially notable in certain regions – in India, for example – where the inebriating properties had religious or magical significance or were otherwise valued. Furthermore, it is thought that often the concentration of the intoxicating principle in any given “race” of Cannabis sativa will decrease as the plant is grown in more northern, cooler latitudes.

Botanists now widely agree that Cannabisis a monotypic genus, a genus with one polymorphic species: C. sativa; that there cannot be recognized any true botanical varieties of this species; and that this one species has diversified into a number of ecotypes and cultivated races. Modern taxonomists, consequently, are in agreement with Linnaeus who, in 1753, recognized only one species.

Nevertheless, a number of binomials have been legitimately published as deserving nomenclatorial recognition. These are such binomials as Cannabis chinensis; C. erratica; C. foetens; C. indica; C. Lupulus; C. macrosperma; C. americana; C. generalis; C. gigantea; C. ruderalis; C. x interstita. As early as 1869, De Candolle recognized several true botanical varieties of Cannabis sativa and offered very detailed taxonomic descriptions of them: α Kif; β vulgaris; γ pedemontana; σ chinensis. Although none of these names is accepted by most modern taxonomists, confusion of nomenclature still reigns in non-botanical literature.

In agricultural, horticultural, chemical and pharmacological publications, it is not uncommon to find in use Latin binomials that have no validity, since they were never validly published. The binomial Cannabis indica is, however, frequently employed as though it represented a species-concept distinct from C. sativa and most often to indicate a race native to India and usually high in intoxicating principles. Even more frequently, pharmacological writings use the name Cannabis sativa var. indica in the belief that there exists a definitive ” varietas ” of Indian origin that may be distinguished taxonomically by having a higher content of the narcotic constituents: a physiological race or chemovar which, it is often asserted, cannot long be maintained in an inappropriate environment or climate. Some specialists have gone even beyond this to distinguish nomenclatorially other varieties. Botanists cannot accept true varieties within Cannabis sativa simply because they cannot define them; and even agricultural and horticultural specialists who often recognize them as true species or varieties admit that they are not stable.

It must be recognized that this problem has arisen because of a confusion of concepts: the true botanical ” varietas ” is genetically distinct; the polymorphism rampant in Cannabis sativa is undoubtedly non-genetic and gives rise to variations that are better called “races “, ” ecotypes “, ” cultivars “, ” chemovars ” or other appropriate terms.

This plasticity of Cannabis has long been recognized. Charles Darwin was impressed with this aggressive weed. He wrote that hemp plants long cultivated can “generally endure with undiminished fertility various and great changes” and be “. so much affected that the proportions and the nature of their chemical ingredients are modified”

Since hemp is a triple-purpose plant long cultivated by man, intensive selection for one characteristic – longer fibre, more seed oil, higher cannabinol content-often leads to an over-shadowing or even disappearance of another characteristic. Races of unusually high yield of seed oil or of superior fibre have been developed which are either inferior in narcotic principles or wholly devoid of them – yet these races may grow in the same region, sometimes even in adjacent fields. On the contrary, highly narcotic races are reported in which the quality of fibre is decidedly inferior, so much so that these strains are commercially worthless – yet, they may grow in the same region, too. In all of these cases, nevertheless, the plants themselves are not taxonomically distinguishable by any stable morphological characters. And, furthermore, the same plants, transported to and cultivated in other climates and environments, yield progeny with alterations in fibre, oil and cannabinol constituency. Much of a basic nature, especially in ecological studies, remains for botanists to unravel.

The dioecious nature of Cannabis sativa – with separate ” male ” and ” female ” plants – constitutes an important consideration since it is believed that, under normal conditions, the narcotics principles occur only in the brownish resin found in the pistillate – not in the staminate – individuals. This resin is concentrated in the inflorescences and leaves, especially those near the flowering tops, and appears to be most abundant in the recently fertilized ovary and unripened fruit. There is, however, still much disagreement in these aspects of the morphology of the plant because of the botanical observations on material from wide areas of the world and on a large selection of “races”

Many organic compounds have been isolated from Cannabis resin, some of which appear to possess narcotic properties, others devoid of euphoric activity. Amongst the constituents are cannabinol, cannabidiol, cannabidiolic acid, tetrahydrocannabinol-carboxylic acid, cannabigerol, cannabichromene and stereoisomers collectively called tetrahydrocannabinol. While most of them are actively euphoric, it has only recently been demonstrated that the main psychotomimetic effects are attributable to Δ 1 -tetrahydrocannabinol. Very little is known as yet about the biodynamic effects on man of pure tetrahydrocannabinol, and, although the literature is rich in the activity of crude Cannabis extracts or products, controlled studies with the active isolates are basic to any progress in understanding the real physiological significance from a moral or health viewpoint of this ancient and widespread intoxicant. Because of the great variation in chemical composition of crude Cannabis preparations normally employed as narcotics, any correlation of biological activity, if possible at all, would be, for all practical purposes, meaningless.

Only a lengthy consideration of hemp can do it justice. Inasmuch as Cannabis represents one of the hallucinogens most widely recognized – even though very imperfectly understood – in modern times, I have resolved to present this obviously brief and superficial discussion and to concentrate on many of the more poorly known or even unknown psychotomimetics utilized in distant and isolated regions by peoples seldom in the attention of the mainstream of society.

The Moraceae also provide one of the most poorly understood hallucinogens: Olmedioperebea sclerophylla, a jungle tree, the fruits of which reputedly were the source of an intoxicating snuff employed formerly by Indians of the Pariana region of the central part of the Amazon Valley. It is now known only by its Portuguese name rape dos indios, “Indian snuff”. No chemical study of this plant nor of the snuff have been published, and direct observations of the preparation and use of the snuff have been impossible to date.

Carpet weed family

More than 225 years ago, it was reported that the Hottentots employed a vision-inducing narcotic plant called kanna or channa. They chewed the root and kept the masticated material in the mouth for some time. ” Their animal spirits were awakened, their eyes sparkled and their faces manifested laughter and gaiety. Thousands of delightsome ideas appeared, and a pleasant jollity which enabled them to be amused by simple jests. By taking the substance to excess, they lost consciousness and fell into a terrible delirium. “

This interesting narcotic plant has never been definitively identified. The vernacular name kanna now is applied in South Africa to species of Mesembryanthemum: M. expansum and M. tortuosum, the roots, leaves and trunk of which are chewed and smoked in the hinterlands. These two species have yielded an alkaloid, mesembrine, which has sedative, cocaine-like effects, producing torpour in man. More than two dozen other species of Mesembryanthemum are known to be alkaloidal.

Unfortunately, no direct evidence connects the Hottentot kanna with Mesembryanthemum, and Lewin, doubting that these aizoaceous plants could produce the effects described, suggests that the narcotic in question must have been Cannabis sativa, to which the Hottentots were very habituated. He likewise hinted that other South African intoxicating plants, such as the anacardiaceous Sclerocarya Caffra and S. Schweinfurthii, should be considered.

Nutmeg family

One of the most widely known and most easily available plant hallucinogens is the well known spice, nutmeg. The handsome tropical tree, Myristica fragrans, native to the East Indian archipelago, is the source of two spices – nutmeg and mace – respectively from the seed and aril of the beautiful fleshy drupe that resembles an apricot.

There is a persistent rumour that the hallucinogenic effects of nutmeg are employed by natives in parts of southeast Asia, but little supporting evidence has been found. It is eaten as a narcotic to-day in India by those who add it to the betel chew, and it may also be employed in India, mixed with tobacco, as a snuff. In the ancient Indian Ayurveda, nutmeg is called mada shaunda, meaning “narcotic fruit”. There are vague reports that nutmeg is snuffed as an intoxicant in the hinterlands of Indonesia, and that in Egypt it is sometimes taken as a substitute for hashish. Whether or not nutmeg is employed in Asiatic and other areas by natives, there is no doubt that it has pronounced psychotomimetic effects and that it is employed as an hallucinogenic narcotic in Europe and the United States in sophisticated circles, by students, by prisoners and by alcoholics and marijuana users deprived of their preferred drugs.

Use of myristicaceouse sunffs

When taken orally, nutmeg, in doses of one teaspoonful or more, may induce hallucinations and other definitely psychotomimetic syndromes in from two to five hours. The intoxication is extremely variable but often is characterized by distortion of time and space perception and a feeling of detachment from reality. Although it is thought that visual hallucinations are infrequent, they definitely do occur in many individuals. Some of the side and after-effects of nutmeg intoxication – headache, dryness of the mouth, dizziness, tachycardia – are distinctly unpleasant.

Toxicological interest in nutmeg is of long standing. As early as 1676, Van Leeuwenhoek noticed that a volatile constituent of nutmeg killed or repelled mites. At the turn of the present century, there was a flurry of pharmacological interest in Myristica fragrans, but it subsided until the recent rash of use of nutmeg as an intoxicant again focussed attention on the need for a thorough understanding of the constituents, effects and dangers of this potential ” new ” hallucinogen.

Although the toxicology of nutmeg is still not wholly elucidated, the principal active constituent in the essential oil appears to be myristicine, the psychoactive properties of which are due probably to several phenylisopropylamines. It has been found that nutmeg and synthetic myristicine are mild monoamine oxidase inhibitors. Safrole and elemicine have also been suggested as active agents in nutmeg seed, although no tests on the psychopharmacological effects of these two constituents have been conducted on which to base such a suggestion.

Amongst many Indian tribes of the northwest Amazon and uppermost Orinoco, a highly intoxicating snuff is prepared from another myristicaceous source: the blood-red bark resin of several species of jungle trees of the genus Virola: V. calophylla, V. calophylloidea, V. theiodora and possibly other species. The snuff is variously known as yakee, paricá, epena and nyakwana, according to the tribe employing the drug.

Virola-snuff was first described in detail and identified as to species in 1954 from ethnobotanical field studies in Amazonian Colombia. The present author found the Indians in the Rio Apaporis basin preparing a brownish, narcotic snuff, known amongst the Puinaves as yakee, from Virola calophylla and V. calophylloidea. It was taken exclusively by witch-doctors in the diagnosis and treatment of disease, for prophecy and divination and for other purposes of magic.

Virola calophylloidea Markgraf

These natives strip the bark from jungle trees early in the morning and scrape off the soft inner bark, with its resinous exudation. These are kneaded in water which, strained, is boiled down to a thick syrup. When the syrup has sun-dried, it is pulverized, sifted and mixed with ashes of the bark of a wild species of Theobroma. The resulting snuff is powerful, causing an intoxication sometimes apparently leading to death.

The German anthropologist, Koch-Grünberg, referred in 1909 to a snuff prepared from a tree-bark amongst the Yekwana Indians of the headwaters of the Rio Orinoco: “Of an especial magical importance are cures, during which the witch-doctor inhales hakúdufha. This is a magical snuff used exclusively by witch-doctors and prepared from the bark of a certain tree which, pounded up, is boiled in a small earthenware pot, until all the water has evaporated, and a sediment remains at the bottom of the pot. This sediment is toasted in the pot over a slight fire and is then finely powdered with the blade of a knife. Then the sorcerer blows a little of the powder through a reed. into the air. Next, he snuff, s, whilst, with the same reed, he absorbs the powder into each nostril successively. The hakudúfha obviously has a strongly stimulating effect, for immediately the witch-doctor begins singing and yelling wildly, all the while pitching the upper part of his body backwards and forwards.”

Virola theiodora: flowering branch; Manaós, Brazil; photograph; R. E. Schultes

The first definite association of a snuff with Virola was made in 1938 by the Brazilian botanist Ducke, who wrote that the “Indians of the upper Rio Negro use the dried leaves of this species [ Virola theiodora] and of V. cuspidata in making a snuff powder that they call paricá “. In 1939, he wrote in a footnote to a discussion of Piptadenia peregrina, that ” Martius and other writers attribute to this species the source of the narcotic paricá employed by certain Amazonian Indians. Notwithstanding, according to information which I obtained from the natives themselves in two localities in the upper Rio Negro, the paricá-powder comes from the leaves of species of Virola. ” Although it is now certain that the leaves are not employed in the snuff-making, this represents apparently the first, and – until 1954 – the only identification of this snuff with the genus Virola.

Gradually, it became evident that perhaps the most intensive use of Virola snuffs might centre amongst the several related Indian groups known collectively as the Waikás inhabiting the very headwaters of the

Orinoco in Venezuela and the Brazilian territory north of the Río Negro and who refer to the snuff as epená and nyakwana.

Unlike other Indians, the Waikás employ Virola snuff both hedonistically and ceremonially, and its use is not restricted to the witch-doctors but is the prerogative of all male members of the tribe. The snuff is taken in excessive amounts and appears to be stronger than that prepared by the natives in Colombia.

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Amongst the Waikás, Virola theiodora is the species employed. Holmstedt and the present author found several variations in method of preparation of epená or nyakwana. Some scrape the soft inner layer of the bark, dry the shavings by gentle roasting over a fire. These are then stored until needed for preparation of a batch of snuff, when they are crushed and pulverized, triturated in a mortar and pestle of a Bertholettia excelsa fruit. The powder is then sifted to a very fine, homogeneous chocolate-brown highly pungent dust. Next, a powder of the dried leaves of an aromatic weedy plant, Justicia pectoralis var. stenophylla is prepared and added in equal amount to the brown dust of Virola. A third ingredient is the ash of the bark of the beautiful leguminous tree Elizabetha princeps, called amá or amasita by the Waikás. The hard, grey outer bark is chopped into small pieces and set in a glowing fire, then removed and allowed slowly to reduce to ashes. When the ashes are added in equal amounts to the Virola-Justicia powder, the resulting snuff, ready for use, is rather greyish and extremely fine.

Waiká Indian grinding the solidified resin of Virola theiodora to prepare nyakwana snuff; Rio Tototobí, Brazil; photograph: R. E. Schultes
Waiká Indians picking stems front leaf material of Justicia pectorails var . stenophylla preparatory to drying and pulverizing them for use with Virola resin in making nyakwana snuff; Rio Tototobí, Brazil; photograph: R. E. Schultes
Waiká Indians snuffing nyakwana (from Virola resin); Rio Tototobí, Brazil: photograph: R. E. Schultes

Other Waiká Indians, who make snuff only occasionally for ceremonial purposes, follow a different procedure. The bark is stripped from Virola theiodora. A fire is built in the forest at the foot of the Virola trees, and the bark is gently heated to cause a copious ” bleeding ” of the red resin which is gathered in an earthenware pot. The resin is boiled down to a thick consistency which, upon cooling, crystallizes into a beautiful amber-red resin. This is then carefully ground up and reduced to an extremely fine powder. This powder alone – without any admixture – is nyakwana snuff. Occasionally, powdered Justicia leaves may be added ” to make the snuff smell better “, but Holmstedt and I ascertained, from self-intoxication, that the Virola resin alone is highly intoxicating.

A still unsolved aspect of the Waiká use of Virola resin is its employment direct and without any preparation or admixture as an arrow poison.

The biodynamic activity of Virola resin was at first presumed to be due to myristicine. Recent investigations, however, have established the presence in the resin of certain Virola species of interesting tryptamines in relatively high concentrations. The Waiká snuff prepared solely from Virola resin has been shown to possess

several tryptamine and, in especially high concentrations, 5-methoxy N, N-dimethyltryptamine. Furthermore, there is preliminary evidence that Justicia pectoralis var. stenophylla may likewise contain tryptamines.

The effects of Virola intoxication vary, but amongst the Indians, they usually include initial excitability – setting in within several minutes from the first snuff- ing – numbness of the limbs, twitching of the facial muscles, inability to co-ordinate muscular activity, nausea, visual hallucinations and, finally, a deep, disturbed sleep. Macroscopia is frequent and enters into Waika beliefs about the spirits that dwell in the plant. A description of my own intoxication indicates several points of interest: “The dose was snuffed at five o’clock. Within fifteen minutes a drawing sensation was felt over the eyes, followed very shortly by a strong tingling in fingers and toes. The drawing sensation in the forehead gave way to a strong and constant headache. Within a half hour, the feet and hands were numb and sensitivity of the fingertips had disappeared: walking was possible with difficulty, as with beri-beri. I felt nauseated until eight o’clock and experienced lassitude and uneasiness. Shortly after eight, I lay down in my hammock, overcome with drowsiness, which, however, seemed to be accompanied by a muscular excitation except in the hands and feet. At about nine-thirty, I fell into a fitful sleep which continued, with frequent awakenings, until morning. The strong headache lasted until noon. A profuse sweating and what was probably a slight fever persisted throughout the night. The pupils were strongly dilated during the first few hours of the intoxication. No visual hallucinations nor colour sensations were experienced.”

Pea family

In view of the heavy concentration of alkaloids in the Leguminosae and the large size of this family – especially in tropical areas – it is not surprising that a number of species have been utilized by primitive peoples as hallucinogens. The surprising circumstance, however, lies in the apparent absence of this family amongst the hallucinogens of the Old World, where the Leguminosae is well represented and includes many toxic species. Of the members of this family known to be employed as hallucinogens, only one – Genista canariensis – is of Old World origin, and even this species is used only by a New World group of natives.

A strongly hallucinogenic snuff, prepared from beans of Anadenanthera peregrina (more widely known as Piptadenia peregrina), is employed in northern South America and was used in pre-colonial times in the West Indies.

The earliest report of what is undoubtedly this snuff, known in the West Indies as cohoba, dates from observations made in 1496 when it was first seen amongst the Taina Indians of Hispaniola.

Friar Ramón Pane, commissioned by Columbus “to collect all ceremonies and antiquities “, wrote in detail concerning this drug and its place in Indian society. His reports were first published in 1511 in Martyr’s compilations about the New World. “This kohobba powder,” which Martyr described as “an intoxicating herb “, “is so strong that those who take it lose consciousness; when the stupefying action begins to wane, the arms and legs become loose and the head droops “. Taking it with a cane about a foot long, they “put one end in the nose and the other in the powder and . draw it into themselves through the nose”. Its action was rapid, for “almost immediately, they believe they see the room turn upside-down and men walking with their heads downwards “. The witch-doctor took the drug with his patients and it “intoxicates them so that they do not know what they do and . speak of many things incoherently “, believing all the time that they are in communication with spirits.

Anadenanthera peregrina

Mentioning hallucinogenic effects, he explained that, after tribal councils, the chief prays and “tells the vision that he has seen, intoxicated with the cogioba which goes up to his head. and he says that he has talked with the cemi“. “Consider what a state their brains are in,” he concludes,” because they say the cabins seem to them to be turned upside down and that men are walking with their feet in the air.”

Snuff from Anadenanthera is apparently no longer employed in the Antilles, where, of course, few aboriginal groups still exist. It was Safford who, in 1916, definitively identified the cohoba reported by the early Europeans as Anadenanthera peregrina. Up to that time, there had been much confusion in the literature, and the snuff called cohoba was commonly considered to have been tobacco. Years earlier, however, in 1898, Uhle had concluded that “the extreme strength of the powder as described by Petrus Martyr, exceeding that of tobacco, decides its different nature and its Piptadenia character”. Safford later pointed out the use of Anadenanthera peregrina in preparing the narcotic yopo-snuff of the Orinoco, still much employed, and established its identity with the ancient cohoba of the West Indies.

The centre of the use of Anadenanthera-snuff is, and probably always has been, the Orinoco basin, where it is widely known as yopo. The West Indian tribes are generally thought to have been invaders from northern South America. If this be true, then the snuffing of Anadenanthera powder in the West Indies could be considered as a culture trait imported from South America. Anadenanthera peregrina occurs wild – that is, undoubtedly free from any hint of present or past cultivation – only in South America, and, as Altschul theorized, the natives of the West Indies ” may have found it easier to plant the trees than to maintain communication with the mainland for their source of supply ” of the snuff.

An early report of yopo amongst the Otomac Indians of the Orinoco basin is that found in Gumilla’s famous El Orinoco Ilustrado, first published in 1741. “They have another most evil habit of intoxicating themselves through the nostrils, with certain malignant powders which they call yupa, which quite takes away their reason, and furious, they grasp their weapons. They prepare this powder from certain pods of the yupa. but the powder itself has the odour of strong tobacco. That which they add to it, through the ingenuity of the devil, is what causes the intoxication and fury. they put their shells [large snails] into the fire and burn them to quicklime. [which] they mix with the yupa . and after reducing the whole to the finest powder, there results a mixture of diabolical strength, so great that in touching this powder with tip of the finger, the most confirmed devotee of snuff cannot accustom himself to it, for in simply putting his finger which touched the yupa near to his nose he bursts forth into a whirlwind of sneezes.

Snuffing tubes and paraphernalia for preparing yopo snuff ( Anadenanthera peregrina ) of the Guahibo Indians, Rio Orinoco, Colombia. Courtesy Botanical Museum of Harvard University

The Saliva Indians and other tribes. also use the yupa, but as they are gentle, benign and timid, they do not become maddened like our Otomacos who. before a battle. would throw themselves into a frenzy with yupa, wound themselves and, full of blood and rage, go forth to battle like rabid tigers.”

A number of other missionary reports from the Orinoco area of Colombia and Venezuela reiterate the details offered by Gumilla. The earliest scientific report on this narcotic appears to be that of Alexander yon Humboldt who botanically identified the plant as Acacia Niopo, stating that the Maypure Indians of the Orinoco break the long pods of this tree, moisten them and allow them to ferment; after they turn black, the softened beans are kneaded into small cakes with Manihot-flour and lime from snail shells. These cakes are powdered when a supply of snuff is desired.

Like Gumilla, von Humboldt felt that the biodynamic activity of the snuff was attributable to the lime admixture: “. It is not to be believed that the niopo acacia pods are the chief cause of the stimulating effects of the snuff used by the Otomac Indians. These effects are due to the freshly calcined lime.”

The earliest detailed scientific report is that given by the British botanical explorer Spruce who met with the drug amongst the Guahibo Indians of the Orinoco basin of Colombia and Venezuela.

The literature concerning the snuffing of narcotic powders has become extraordinarily confused. There is no doubt but that sundry wholly unrelated plants enter into South American snuffs. Undoubtedly the most important snuffing material was and still is tobacco, mainly from Nicotiana Tabacum, and snuffing may well be the most widespread method, especially in the wet, tropical lowlands areas, of using tobacco. In certain areas of the northwest Amazon, coca-powder ( Erythroxylon Coca) is snuffed. Recent studies have shown the importance and widespread employment of intoxicating snuffs made from Virola-bark. Yet the literature – especially the anthropological – has unwarrantably exaggerated the importance of the leguminous snuffs from Anadenanthera ( Piptadenia).

Many reports ascribe the sources of Amazon snuffs to various leguminous trees, and the British botanist Bentham’s concluded that “all South American trees. referred to as the source of narcotic snuff were probably one species and were identical with Linnaeus’ Mimosa peregrina“. It seems that one of the most extraordinarily mistaken generalizations in ethnobotany – that all the intoxicating snuffs of the Amazon that were not obviously tobacco must have been prepared from Anadenanthera peregrina – has stemmed from Bentham’s conclusion. Recent literature and maps showing the distribution of snuffs made presumably from Anadenanthera include the entire Orinoco basin and adjacent areas of southern Venezuela to the east; westward across the northern Colombian Andes, much of the Magdalena Valley; down the Andes through Colombia, Ecuador, Peru and Bolivia; the coastal region of Peru; scattered isolated areas in northern Argentina and the central and western Amazon Valley. One must remember that not one species – Anadenanthera peregrina – is involved but that there have been suggestions that other species of this genus have entered the South American snuff-making picture.

Tree of Anadenanthera peregrina in the campos outside of Boa Vista, Brazil; photograph: R. E. Schultes

Anadenanthera peregrina is a species that occurs naturally and cultivated in the open plains or llanos region of the Orinoco basin of Colombia and Venezuela, in savannahs and light forests in British Guiana and in Brazil in the open grasslands or campos of the Río Branco region and locally in savannah-like areas in the lower Río Madeira basin. If Anadenanthera peregrina is found elsewhere, it occurs as a rare tree or two brought in and cultivated by recently migrated Indian tribes.

As a consequence of the comparatively restricted distribution of Anadenanthera peregrina, the use of a snuff prepared from its beans obviously must be much more restricted than the literature would indicate. This I believe to be true. As examples, we might cite de la Condamine’s observation in the early eighteenth century of an hallucinogenic snuff known as curupa amongst the Omaguas of Amazonian Peru and a modern statement that the Tikunas of the upper Amazon both used a snuff made from Anadenanthera peregrina: since this species is unknown from the area inhabited by the Oma- guas and Tikunas, the attributing of the snuff to A. peregrina must be seriously questioned.

Even within the local range of Anadenanthera peregrina, it is not safe to assume that all narcotic snuffs are referable to this species. A number of erroneous ” identifications ” of narcotic snuff amongst Indians of the uppermost Orinoco in Venezuela and northern affluents of the Río Negro in Brazil – especially amongst the Waikás – have attributed powders prepared from Virola bark to Anadenanthera peregrina. One reason for this confusion may be due to the fact that in many parts of the Amazon – especially in the Río Negro basin, the term paricá, which does often refer to leguminous trees, has been applied to narcotic snuff from Anadenanthera and Virola indiscriminately.

Until recently, there has been much uncertainty concerning the active hallucinogenic principles of Anadenanthera peregrina. At one time, it was felt that the central nervous activity of yopo-snuff was due mainly, if not wholly, to 5-hydroxy-N, N-dimethyltryptamine or bufotenine. Recent analyses of carefully authenticated and identified material, however, has shown that other tryptamine derivatives are present in the seeds of Anadenanthera peregrina: N, N-dimethyltryptamine, N-monomethyltryptamine, 5-methoxy-N, N-dimethyltryptamine, 5-methoxy-N-monomethyltryptamine, N, N-dimethyltryptamine-N-oxide, 5-hydroxy-N, N-dimethyltryptamine-N-oxide.

Anadenanthera peregrina is a beautiful, medium-sized tree with a thick, corky bark. The crown is graceful with its dark green, acacia-like foliage.

Other Anadenanthera species

It was Safford apparently who first suggested that species of Anadenanthera other than A. peregrina may be the source of narcotic snuffs in South America. He identified the vilca or huilca of southern Peru and Bolivia and the cébil of northern Argentina with seeds of what he called Piptadenia macrocarpa, now referred to as Anadenanthera colubrina var. Cebil. Some evidence suggests that vilca may have been employed in forms other than as snuff. Although the evidence is wholly circumstantial and often rather weak at that, several species or varieties of Anadenanthera may actually be involved in the numerous isolated localities in central and southern South America where snuff was employed amongst the Indians. We know with certainty that snuffing was practiced because of the many implements – trays, tubes and other paraphernalia – that have turned up as archaeological remains or in recent collections of ethnographic artifacts.

The term vilca in modern Peru sometimes refers to Anadenanthera colubrina, although this or similar names signify a number of different plants in South America. An early report, dating from about 1571, stated that Inca witch-doctors prophesied by contacting the devil through an intoxication induced by drinking chicha and an herb called villca. Even earlier records mentioned a medicinal plant of this name, some of them emphasizing its laxative and emetic properties. The cébil snuff used in northern Argentina at the time of the arrival of the Spaniards appears ” to have been Adenanthera-derived “, although ” the use of this genus further south beyond its natural distribution is less likely. Yet there, further south, the Comechingon Indians took something called Sebil through the nose . and the Huarpe Indians chewed a substance called Cibil for endurance. “

Howsoever weak and circumstantial the evidence that vilca and cebil were prepared from Anadenanthera, there would seem to be no phytochemical reason why this might not be so. Anadenanthera colubrina has been shown by Altschul to be very closely related morphologically to A. peregrina. Furthermore, some of the same hallucinogenic tryptamines found in varying proportions in Anadenanthera peregrina have been located in material said to be referable to A. colubrina.

It is obvious that extensive research must be done on South American hallucinogenic snuffs in general and on the use of Anadenanthera in particular before anything approaching a clear understanding of the total picture can be expected.

There exists the possibility that, in some parts of Mexico, several species of Erythrina have been used locally as hallucinogens. The seeds of some species of Erythrina resemble the mescal bean ( Sophora secundiflora) which has a long history of use as a narcotic in the American Southwest and northern Mexico. The vernacular names for the two kinds of red seeds are often the same: colorines; and the two are sometimes sold in the market places mixed together. Several species of Erythrina contain toxic indole or isoquinoline derivatives.

There is evidence that natives of the New World have found psychotropic activity in plants introduced from the Old World. It has been recently reported that Yaquí medicine men from northern Mexico employ Genista canariensis, the genista of florists, for the purpose of inducing hallucinations. This property of the plant has been experimentally substantiated. The genus Genista and the closely related Cytisus, in which G. canariensis is sometimes included, are extremely rich in alkaloids. Cytisine, an alkaloid that formed the basis for the hallucinogenic use amongst some North American Plains Indians of seeds of the leguminous Sophora secundiflora, has been isolated from leaves and beans of Genista canariensis. There is, apparently, no record of the hallucinogenic use of Genista canariensis in the Old World.

The Kariri, Pankarurú, Tusha and Fulnio tribes of Pernambuco and Paraiba in eastern Brazil employ the leguminous shrub Mimosa hostilis in the preparation of a “miraculous drink” known as ajuca or vinho do jurema taken in the ajuca ceremony. The roots of the plant, which grows in the dry scrubby caatinga vegetation, are the source of the intoxicant. This cult, apparently, is ancient, having formerly been practised by a number of other tribes – Guegue, Acroa, Pimenteira, Atanayé – some of which have become extinct. An early report of jurema dates from 1788. Another record, dating from 1843, asserted that, among a number of tribes, jurema was taken in order to “pass the night navigating through the depths of slumber” and, by relating it to the use of paricá ( Anadenanthera peregrina and ipadú ( Erythroxylon Coca), seems to indicate hedonistic employment of jurema.

This potent hallucinating drink merits deeper study. Amongst the Indians who still utilize it, groups of priests, warriors or strong young men and old women singers participate in the ceremony – all kneeling with heads bowed to receive their portion of the drink. The ceremony formerly was performed especially before going to war. A very recent description of the jurema cult records that “an old master of ceremonies, wielding a dance rattle decorated with a feather mosaid, would serve a bowlful of the infusion made from yurema roots to all celebrants, who would then see glorious visions of the spirit land, with flowers and birds. They might catch a glimpse of the clashing rocks that destroy souls of the dead journeying to their goal, or see the Thunderbird shooting lightning from a huge tuft on his head and producing claps of thunder by running about.”

Apparently several species of Mimosa are generically referred to as jurema in northeastern Brazil. One of the several kinds of jurema prêta is the Mimosa hostilis from which the intoxicant is prepared. This species is sometimes also known as jurema branca, although this name may refer also to Mimosa verrucosa, from the bark of which a stupefacient is said to be derived. An alkaloid was isolated from the bark of the roots in 1946 and named nigerine, but recent chemical studies have established the identity of nigerine with N, N-dimethyltryptamine, the same hallucinogenic constituent isolated from the seeds of the related Anadenanthera peregrina.

In Oaxaca, Mexico, a number of species of Rhynchosia, especially R. phaseoloides and R. pyramidalis, are known by the name piule, a kind of generic term signifying narcotics, sometimes applied to the hallucinogenic morning glory seeds and sacred mushrooms. These red and black beans are also known in Mexico as colorines and are equated together with hallucinogenic mushrooms on the slopes of Mt. Popocatepetl.

There is evidence that in southern Mexico Rhynchosia seeds may be employed as a divinatory narcotic. The Chinantecs and Mazatecs of Oaxaca consider them poisonous. Although there are no definite indications in the literature of their use in pre-Conquest times, they may be represented together with mushrooms, falling from the hand of the Aztec god of rain, in the Tepantitla fresco which dates from 300-400 AD.

Rhynchosia seed from Oaxaca gave positive reactions for alkaloid and glycoside tests and produce a kind of intoxication with trogs. An unidentified alkaloid has been isolated from seeds of Rhynchosia pyramidalis.

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A shrub native to the dry limestone areas of the American Southwest and adjacent Mexico, Sophora secundiflora produces dark red seeds known as mescal beans, red beans or coral beans. In Mexico, the vernacular name is frijolito, frijolillo or colorines. These seeds, formerly the basis of a vision-seeking, cult, contain a highly toxic alkaloid, cytisine, the effects of which somewhat resemble nicotine, causing nausea, convulsions, hallucinations and occasional death from respiratory failure.

Sophora secundiflora

Sophora secundiflora is a beautiful shrub – often planted as an ornamental in Texas – with leathery, evergreen leaflets and large inflorescences of violet or violet-blue flowers and woody legumes containing usually three or four beans. The genus Sophora comprises some 25 species of the warmer and tropical parts of both hemispheres, a number of which likewise contain cytisine or a related alkaloid. No other species, however, has apparently been employed for narcotic purposes.

A report by the Spanish explorer of the Texas coast, Cabeza de Vaca, mentioned mescal beans as an article of trade amongst the Indians in 1539. The Stephen Long Expedition in 1820 reported the Arapaho and Iowa using large red beans as a medicine and narcotic. They have been found in archaeological sites, all dated before 1,000 A.D., sometimes with evidence of possible ritualistic use of the beans. They have been recorded for at least 12 cave and rock shelter archaeological sites in southwestern Texas, and material from sites in northern Mexico has been carbon-dated to between 7,5000 B.C. to 200 A.D., thus substantiating the antiquity of the use of this poisonous bean. Although “the presence of mescal beans in cave and rock shelter sites, even when included in containers holding utilitarian as well as nonutilitarian objects, does not,” writes Campbell,” necessarily signify the presence of a mescal bean cult. There is additional archaeological evidence which does suggest the presence of a prehistoric cult that may have involved the use of the mescal bean.”

A well developed mescal bean cult was present amongst the Apache, Comanche, Delaware, Iowa, Kansa, Omaha, Oto, Osage, Pawnee, Ponca, Tonkawa and Wichita tribes. Other tribes of the central and northwestern American Plains groups valued the bean as a medicine or fetish but failed, apparently, to develop a definite cult surrounding its use. In the cult- known variously as the Wichita Dance, Deer Dance, Whistle Dance, Red Bean Dance and Red Medicine Society – the seeds were employed ritualistically or not as an oracular or divinatory medium for inducing visions in initiatory rites and as a ceremonial emetic and stimulant.

There are many parallels and similarities between certain aspects of the modern peyote cult and the Red Bean Dance, and both obviously had a southern origin because of the natural distribution of the plants involved. It appears wholly probable that the Red Bean Dance was pre-peyote in the Plains groups where its role as a sacred narcotic was lost or forgotten with the arrival of the much safer hallucinogenic cactus. Even to-day, amongst the Kiowa, Comanche, and other tribes, the leader or ” roadman ” of the peyote ceremony often wears, as part of his ornamental dress, a necklace of Sophora secundiflora beans.

Necklace of beans of Sophora secundiflora used by leader of Kiowa Indian peyote ceremony, Anadarko, Oklahoma. Courtesy Botanical Museum of Harvard University, Cambridge, Massachusetts

An ethnobotanically and pharmacologically most interesting practice is the reported mixing in a narcotic drink of peyote and mescal beans amongst the Comanche, Oto and Tonkawa. This drink, practised probably in transitional periods between the dying out of the Red Bean Dance and the establishment of the peyote cult, must indeed have been a potent – if not a dangerous – narcotic preparation. This may possibly be responsible for the confusion in certain early literature of the terms mescal beans and peyote.

Domestication of aromatic medicinal plants in Mexico: Agastache (Lamiaceae)—an ethnobotanical, morpho-physiological, and phytochemical analysis

Most reports of domesticated plants that involve a domestication gradient or inter-specific hybridization in Mexico have focused on those used as food. This study provides knowledge about these processes in two aromatic medicinal plants, Agastache mexicana (Lamiaceae) and A. m. subsp. xolocotziana, widely used in Mexican traditional medicine for the treatment of gastrointestinal ailments and for their sedative effect. Different populations of A. mexicana along a gradient of domestication are found in the foothills of the Popocatepetl volcano of central Mexico, while in this same area the subsp. xolocotziana grows only in the cultivation, possibly a product of hybridization between A. mexicana and Agastache palmeri. This study links ethnobotanical, morpho-physiological, and phytochemical evidence to document the domestication of both taxa as well as elucidates the possible hybrid origin of the subsp. xolocotziana.


We analyze three groups of data derived from (1) 80 semi-structured interviews aimed at documenting the selection criteria related to the use and management of A. mexicana; (2) a cultivation experiment under homogeneous conditions, evaluating 21 floral, vegetative, and seed characters (that were important according to ethnobotanical information) in 97 plants corresponding to 13 populations of the taxa under study; and (3) the chemical profiles of the essential oils of these plants by means of a thin-layer chromatography.


By linking the three types of evidence, two evolutionary processes are distinguished: (1) A. mexicana occurs in the encouraged-cultivated phases of the domestication gradient and (2) A. m. subsp. xolocotziana may have originated through inbreeding depression or hybridization. These two cultivated plants show a domestication syndrome based upon organoleptic differentiation due to their dissimilar phytochemical composition and gigantism in flowers, seeds, and rhizomes (the last enhancing their asexual reproductive capacity). In addition to this, A. mexicana exhibits more intense floral pigmentation and foliar gigantism while subsp. xolocotziana presents floral albinism and partial seed sterility.


Two divergent evolutionary processes are reported for the domestication of A. mexicana as a result of the intensification of its use and management. The selection processes of these plants have resulted in alternation of the organoleptic properties based upon the divergence of the phytochemical composition. Also, gigantism has been selected in culturally preferred plant parts and in correlated structures. The preceding characteristics reinforce the joint use of these plants in infusion in Mexican traditionalmedicine for the treatment of gastrointestinal diseases and for their sedative effects.


Domestication consists of evolutionary, dynamic, continuous, and multidirectional processes which lead the populations involved to a greater fitness through the selection that the human exerts on them, according to their use and management [1]. The domestication of plants in Mexico involves different degrees along a domestication gradient ranging with four major stages. The wild progenitors receive no conscious human attention, although they may be exploited. The tolerated individuals are allowed to persist usually in anthropogenic habitats contrary to other elements of the vegetation that are eliminated. The encouraged plants are promoted so as to favor the reproduction of the selected individuals with desirable characteristics and are subject to practices that improve to some degree the conditions in which they develop (e.g., protection against competitors and herbivores) [2,3,4,5,6,7]. Mexican examples include quelites [alaches (Anoda cristata (L.) Schltdl.) and quelite de agua Amarantus retroflexus L.)], bonnets (Jacaratia mexicana A. DC.), and hog-plums (Spondias purpurea L.). The domesticated plants have a greater fitness under cultivation and are propagated from vegetative parts, seeds, and/or transplants of complete individuals. Among the Mexican domesticates are maize (Zea mays L.), pumpkins (Cucurbita pepo L.), and beans (Phaseolus vulgaris L.) [2,3,4,5,6,7]. In other cases of domesticated plants such as prickly-pear cactus (Opuntia ficusindica (L.) Mill.), guajes (Leucaena spp.), and agaves (Agave spp.) [8,9,10], inter-specific hybridization is an important mechanism of domestication and is currently of great interest [11]. The common suite of differential characteristics between cultivated domesticates and their ancestors (wild, tolerated, encouraged, or parental in the case of hybridization) is known as domestication syndrome, which includes gigantism in used parts and correlated structures, indicating its evolutionary process under domestication [1, 12].

Little is known about the domestication of medicinal plants in Mexico where between 3000 and 5000 native and introduced species are used by more than 69 indigenous peoples of the country. The main botanical families used in Mexican traditional medicine (MTM, hereafter) are Asteraceae, Lamiaceae, Solanaceae, in which many of their species are aromatic [13, 14].

Ethnopharmacological studies among the Popoluca (Veracruz), Mixe (Oaxaca), and Maya (Chiapas and Yucatán) indicate that aromatic organoleptic properties are a determinant for the consumption of plants for medicinal purposes ([15,16,17,18,19], respectively). These studies along with Geck et al. (2017a,b) confirm that odor and taste of plants are immersed in the culture, resulting in various organoleptic categories such as sweet, bitter, spicy, sour, fetid, among others [20, 21]. These characteristics are considered the main criteria in determining the appropriate treatment to alleviate given ailments. For example, among the Mixe people, sweet aromatic plants are preferred in the treatment of gastrointestinal ailments [16].

In addition, the plant’s morphology influences its preference for medicinal use. In the case of epazote (Dysphania ambrosioides (L.) Mosyakin and Clemants), leaf color, size, and shape, in addition to the organoleptic characteristics, are selection criteria of mestizo inhabitants with Mazatec ancestry of Santa María Tecomavaca, Oaxaca, to differentiate their employment of different forms as a condiment or an antiparasitic medication [22].

Genetic, environmental, and ecological variables, as well as the stage of plant’s development (seedling, plantlet, flowering or fruiting, etc.), influence their organoleptic characteristics, which are directly related to the chemical composition of their essential oil [23, 24]. Similarly, these variables contribute to the wide phenotypic variation within and between populations [24]. These variations in the domestication complex due to genetic selection need to be distinguished from the consequences of phenotypic plasticity in response to environmental variables [25]. It is important to demonstrate that management and selection lead to a morpho-physiological and organoleptic differentiation based upon genetic and phytochemical divergence between cultivated populations and their wild ancestors (the progenitor species or, in case of hybridization, the parental species). Several studies have suggested that the design of a common garden with homogeneous conditions reduces environmental variability. Thus, the expression of genetically based morphological and phytochemical differentiation between wild and cultivated populations allows one to identify selection criteria that humans have exerted on them [22, 26].

A good model to generate knowledge about the domestication process in aromatic medicinal plants of Mexico is Mexican hyssop belonging to the genus Agastache section Brittonastrum (Lamiaceae; Mentheae). Both Agastache mexicana (Kunth) Lint and Epling and Agastache mexicana subsp. xolocotziana Bye, Linares & Ramamoorthy are known in the MTM as “toronjil morado” and “toronjil blanco,” respectively, and are used together in infusions for their calming effect [27]. A. mexicana grows spontaneously and under cultivation throughout the Neovolcanense Province of central Mexico, especially in region of the Popocatepetl volcano, in the Ozumba Municipality, State of Mexico (Edomex), and in the Milpa Alta County, Mexico City (CDMX) [28, 29].

The subsp. xolocotziana only occurs in a cultivated state in central Mexico (CDMX, Edomex and Morelos). The absence of wild populations with white flowers, sterile pollen, and fruits, and vegetative reproduction via rhizomes, suggest that this taxon may be a product of hybridization [27]. Given the proximity of allopatric populations and the capacity of humans to breach the geographical barrier with A. mexicana (pine-oak forest, between 2800 and 3200 m asl), Agastache palmeri (B.L. Rob.) Standl. (of southern Sierra Madre Orientalense, especially in pine forest of Hidalgo and Puebla, between 2900 and 3200 m asl) was proposed as the other putative parental species [27, 30].

The basis of this hypothesis is that this subspecies has (a) morphologically intermediate phenotype, a single report of a morphologically intermediate, sterile hybrid between A. mexicana and A. palmeri [30]; (b) reduction in sexual reproduction, low viability in pollen (30%) compared to A. mexicana and A. palmeri (80% in both cases) [30; personal communication R. Bye]; (c) asexual reproduction, its propagation is vegetative through rhizomes [27]; and (d) novel characters such as the presence of approximately three times more compounds in the essential oil of the subsp. xolocotziana (38 compounds) compared to those found in A. mexicana (11 compounds) [31].

Documenting domestication processes in aromatic medicinal plants elucidates their evolutionary dynamics and compares its syndrome with other groups of plants used for other purposes. Hence, we can also lay the groundwork for understanding the domestication process in this complex and diverse group, little studied from this perspective [25]. This information is also the basis for implementing conservation and management strategies for these fundamental therapeutic resources in the MTM [32].

The objectives of this report are (1) to provide ethnobotanical, morpho-physiological, and phytochemical evidence for the understanding of the domestication processes of A. mexicana, by comparing different populations found along the domestication gradient, and the subsp. xolocotziana contrasting it with the putative parents, and (2) to generate information about the possible hybrid origin of latter taxon. We expected (1) the existence of organoleptic, morpho-physiological, and phytochemical dissimilarities between the populations involved in the domestication gradient of A. mexicana and in the populations of A. m. subsp. xolocotziana with respect to their putative parents, and (2) a pattern of differentiation of characteristics that coincide with hybridization as a possible origin of subsp. xolocotziana.

Materials and method

Studied species

Agastache mexicana (purple Mexican hyssop) and its subsp. xolocotziana (white Mexican hyssop) are aromatic herbs important in MTM. They are known and used beyond their natural geographic range, grown under cultivation, and commercialized internationally [13, 27]. Ethnobotanical, taxonomic, and phytochemical studies support their taxonomic relationship. The typical A. mexicana has an anis odor, purple corolla, triangular leaves with serrate margin in the lower blade, and essential oils with 11 compounds (the most abundant being estragole and limonene). Its subsp. xolocotziana has a mentholated odor, white corolla with trichomes on its lower lip, lanceolate leaves and crenate margin, and essential oils with 38 compounds (the most abundant being pulegone and limonene) [27, 31, 33].

The first written mention of A. mexicana occurred in the sixteenth century (1552) when it was registered in Libellus de medicinalibus indorum herbis, one of the oldest manuscripts of Mexican medicinal plants (also known as Codex de la Cruz-Badiano), under the Nahuatl name of tlalahuehuetl; its sap was applied to wounds [34,35,36]. A decade later, Francisco Hernández, the physician of the Spanish King Philip II, recorded tlalahoehoetl in the treatment of gastrointestinal ailments, urinary problems, and ophthalmological disorders in central Mexico [27, 37]. On the other hand, the use of the subsp. xolocotziana was not recorded until the twentieth century (1939) in Las Plantas Medicinales de México, being reported to treat gastrointestinal ailments and as an anti-spasmodic [38]. Currently, both aromatic herbs combined together in an infusion are drunk for treating gastrointestinal, cardiovascular, menstrual, and nerve pains; the “toronjiles” are also used to combat insomnia, as a sedative, and in the treatment of culturally affiliated ailments such as “susto” or “espanto” [27, 39, 40].

Recent phytochemical and pharmacological studies report the analgesic and anti-inflammatory effect of the organic extract of both taxa [40,41,42]. Similar extracts of A. mexicana relax bronchial smooth muscles of the guinea pig (Cavia sp.) [43] while those of subsp. xolocotziana induce contractions [44]. Anticonvulsant effect of the extracts of both taxa along with Dracocephalum moldavica L., an introduced Lamiaceae known as “toronjil azul” (blue hyssop), has been documented [45]. These three toronjiles (purple, white, and blue) form part of the “ethnobotanical medicinal complex toronjil” [46].

Study area

Based upon bibliographic searches, survey of specimens in the National Herbarium (MEXU–Herbario Nacional de México), and visits to markets in central Mexico, the following taxa and their management regime were detected: A. mexicana—cultivated and encouraged, A. mexicana subsp. xolocotziana—cultivated, and A. palmeri—tolerated. Three field study sites were selected (Fig. 1, Table 1):

Geographic location, study sites and management categories of A. mexicana, A. m. subsp. xolocotziana, and A. palmeri in central Mexico. The images of the inflorescences illustrate the color variation according to the taxon and the management category

Table 1 Taxa, management category, number of populations, number of individuals per population, total individuals, and sites considered in the morphological variation analysis. Initially, ten individuals were included in each population, however some did not survive

1. Santiago Mamalhuazuca, Ozumba, Edomex. The municipality of Ozumba, located in the foothills of the western part of the Popocatepetl volcano (between 1800 and 2600 m asl; temperature ranges between 12 and 20 °C; precipitation between 800 and 1000 mm). The population is 27,207 inhabitants, the majority mestizos conserving a small Nahuatl indigenous sector (1.1%) [47, 48]. Cultivation and marketing of medicinal plants are major economic activities in this village. The principal species include A. mexicana, Heterotheca inuloides Cass., Tagetes lucida Cav., and Justicia spicigera Schltdl [29].. At this site, cultivated populations of both A. mexicana and the subsp. xolocotziana are found.

2. San Pablo Oztotepec, Milpa Alta, CDMX. Milpa Alta county is located in southern CDMX (average elevation 2420 m asl.), with a population of 130,582 persons, including the largest Nahuatl population in Mexico City [47]. The harvesting of medicinal plants, including A. mexicana, supplies the central medicinal plant market (Mercado Sonora) in downtown Mexico City [28]. In this locality, only encouraged populations of A. mexicana were found.

3. Puerto de Piedra, Nicolás Flores, Hidalgo. The municipality Nicolás Flores is located in the state of Hidalgo in the Sierra Madre Oriental mountain range, with 7031 inhabitants, where approximately half speak an indigenous language, mainly Otomi [47]. The vegetation is mainly pine-oak forests (elevations from 900 to 2800 m asl; precipitation from 800 to 1100 mm; temperature between 12 and 22 °C); part of this territory belongs to the Los Mármoles National Park. Also at this locality, tolerated populations of A. palmeri var. breviflora R.W. Sanders were managed.

Ethnobotanical evidence

In the first two study sites, Ozumba, Edomex, and Milpa Alta, CDMX, visits were made every 2 months over a 2-year period. A total of 80 semi-structured interviews were conducted (40 at each site), in addition to botanical walks, participant observation and collection of plant material (seeds and complete plants) to document traditional knowledge, uses, and selection criteria (organoleptic and morpho-physiological characteristics) according to their use and management [16, 22, 49, 50]. The selection of the people for interviews was carried out by means of a “snowball” sampling [51]. The analysis of ethnobotanical data was carried out through summary statistics. In the third site, Nicolás Flores, Hidalgo, only seeds and complete plants of A. palmeri collected to document the two categories of evidence described below.

Morpho-physiological evidence (under standardized conditions)

A common garden experiment was established within a greenhouse located in the Botanical Garden of the Institute of Biology (Instituto de Biología) of the National Autonomous University of Mexico (Universidad Nacional Autónoma de México) in Mexico City. Twenty-one morpho-physiological characters (vegetative, inflorescence, flowers, and seeds) were evaluated. These characters were based upon criteria for the use and management of these plants derived from the ethnobotanical inquiries (shown in Table 2, in addition to germination percentage). Because the harvest of the “toronjil” occurs when it blooms, data collection was carried out at the floral stage.

Table 2 Characters evaluated in the analysis of principal components and eigenvectors of the first and second principal components

Through a completely randomized design, four treatments were established consisting of three factors: (a) taxon, (b) degree of management, and (c) population. The treatments consisted of (1) A. mexicana + encouraged + Milpa Alta; (2) A.mexicana + cultivated + Ozumba, (3) A. m. subsp. xolocotziana + cultivated + Ozumba, and (4) A. palmeri + tolerated + Nicolás Flores. For each treatment, seeds were collected from three different populations in each location, except the first, where four populations were collected. The analysis of the morphological variation was obtained from a total of 13 populations and 97 individuals (Table 1). From each field population, voucher specimens were collected and deposited in the National Herbarium (MEXU).

Statistical analysis of morpho-physiological characters

All analyses were performed with the Software R ver. 1.0.153 [52]. In order to document the pattern of grouping and discontinuities in the total variation, two analyses were made: (1) cluster analysis and (2) principal component analysis (PCA). For the first analysis, a matrix of population means was used, whose elements were standardized to mean = 0 and variance = 1; subsequently, a distance matrix was obtained using the square of the Euclidean distance. Cluster analysis was performed using the average distance method (unweighted pair group method using arithmetic mean—UPGMA) and represented by a dendrogram using a standardized average distance as weight. The total populations and characters were considered in this analysis.

The PCA was performed to analyze the relationship between the taxa under study and estimate the importance of the characters that discriminate among them. This analysis was carried out using a matrix that included 97 individuals and 20 morpho-physiological variables (the germination percentage variable was not considered for this analysis because it was obtained on the basis of populations rather than on individuals). Similarly, the elements of the matrix were standardized to mean = 0 and variance = 1. Subsequently, the matrix of correlations between the variables was generated, which served as the basis for calculating the characteristic values and vectors; next, the study units (individuals) were projected on the axes that represent the first two principal components.

In order to document significant differences between management categories and domestication trends in the 21 characters evaluated, we framed our analyses upon two questions. First, what are the differences between the encouraged and cultivated populations of A. mexicana? For this, Student’s T test was carried out considering a total of 53 individuals of A. mexicana (encouraged (29) and cultivated (24)). Second, what are the differences between the subsp. xolocotziana and its putative parents? For this question, an ANOVA was carried out considering a total of 73 individuals (subsp. xolocotziana (22), A. mexicana encouraged (29), and A. palmeri (22)).

In all cases, normality and homogeneity, Shapiro-Wilk and Levene, respectively, were determined prior to the analyses. Tukey’s post hoc test was used when necessary. When the variables did not meet the assumptions of normality and homogeneity, a Kruskal-Wallis test was used.

Phytochemical evidence

Essential oil extraction

Once the morpho-physiological evaluation of the plants was completed, the essential oil was extracted from the aerial parts of the plants (stem, leaves, and inflorescence) for each population using hydrodistillation. Fifteen grams of pulverized plant material were extracted in 250 ml of distilled water to attain a final volume of 90 ml of an emulsion of essential oil and water. The essential oil was obtained by partition with ethyl acetate (1:1). The organic phase was recovered and concentrated under reduced pressure at a maximum temperature of 40 °C resulting in a final volume of 2 ml. The essential oil was stored in amber vials and kept refrigerated (4 °C) for further chemical profile analysis.

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Thin layer chromatography

The chemical profile of the essential oil from each population was obtained by means of a thin layer chromatography (TLC); five main aromatic compounds were reported for “toronjil” ethnobotanical complex: estragole, geraniol, linalool, menthone, and pulegone [40, 53]. The analytical conditions of the TLC were the following: the stationary phase consists in silica gel chromatoplates (TLC silica gel 60 F254; Merck), the mobile phase was toluene–ethyl acetate (95:5), UV light (254 and 360 nm), and anisaldehyde reagent derivatization [54]. For each compound analyzed, the retention factor (Rf) was calculated. Subsequently, the absence or presence of the five standards mentioned for each population was scored. The comparison was made by management categories.


Ethnobotanical evidence

The 80% of the people interviewed mention that the infusion combining A. mexicana and the subsp. xolocotziana is drunk to treat principally (75%) gastrointestinal, menstrual, and nerve pains as well as to combat “coraje” (an intense anger or disgust said to be an emotion expressed by great irritability) and secondarily (60%) in cases of “susto” or “espanto” (an ailment of cultural affiliation generated from an impression or deep fear, whose physical characteristics are: sunken eyes and yellow irises, paleness, loss of hunger, exhaustion, insomnia or drowsiness, and anxiety) [39]. Along with drinking the infusion, one is bathed nightly in a tub of hot water containing the “toronjiles,” until one is relaxed. In third place (40%), A. mexicana in form of poultices and infusions is recommended to alleviate pain generated by contusions. For treating these ailments, the people preferred using A. mexicana and the subsp. xolocotziana instead of árnica (Heterotheca inuloides Cass.) which is similarly employed.

Traditional knowledge and selection criteria

Eighty percent of the people interviewed recognized two categories of A. mexicana: “toronjil morado de monte” (purple wild hyssop) and “toronjil morado de casa” (purple house hyssop) referring to the encouraged and cultivated populations, respectively. They differentiated the two based mainly on organoleptic (60%), floral (30%), and vegetative (10%) characteristics. The purple wild hyssop has a smell and taste of hyssop, that is, with a menthol aroma and with pale purple flowers, while the purple house hyssop has a strongly aniseed, sweet taste, and smell, with a more intense color of the leaves and flowers more intense than that of the wild one. The purple house hyssop is preferred over the wild to treat the ailments described above having greater consumption and effectiveness when the plants are in the floral stage.

Hundred percent of the informants referred to the subsp. xolocotziana as “toronjil blanco de casa” (white house hyssop) and mentions that this plant does not occur in the wild. They differentiate it from other hyssops mainly for their floral (70%), organoleptic (60%), and vegetative (30%) characteristics. They distinguish it by its flavor and smell of menthol, white flowers, olive-green leaves, and a stout rhizome.

The 80% of the people interviewed mentioned that purple and white house hyssops are highly valued for their medicinal effectiveness when consumed together as an infusion, having greater effectiveness when plants are in the floral stage and consumed in fresh. However, 50% also use them in the form of vegetative shoot or as shade-dried plants.


Encouraged populations of A. mexicana

All the people interviewed in San Pablo Oztotepec recognized that plants of purple wild hyssop tend to grow in disturbed habitats near “milpas,” traditional agricultural fields. The plants are valued for their medicinal and ornamental use and increase in density in response to weeding so as to remove other plants compete with them. At the time of harvesting these plants, people only cut the aerial part, leaving the rhizome so that it can produce new shoots during the next growing season. Another practice is that not all plants are harvested at the flowering time, thus leaving some inflorescences to produce seeds that subsequently fall to the ground and germinate.

Cultivated populations of A. mexicana and A. m. subsp. xolocotziana

Agastache mexicana and its subsp. xolocotziana (purple and white house hyssop, respectively) are widely cultivated in the town of Santiago Mamalhuazuca. Propagation is mainly done through the rhizome. However, 30% of the informants mention that they produce seedlings to introduce plants that are hardier and more resistant to environmental variations. However, in the case of white house hyssop, they mention that “few seeds germinate” and of those, they select the most vigorous plants to transplant although not all survive.

The interviewees of Santiago Mamalhuazuca mentioned that the white house hyssop is “chiquión” (that it does not withstand extreme changes in temperature and humidity) while the purple house hyssop is more resistant. The inhabitants of this town also cultivate other medicinal plants in their fields, such as fennel (Foeniculum vulgare Mill.), borage (Borago officinalis L.), rue (Ruta chalepensis L.), gordolobo (Gnaphalium spp.), pericón (Tagetes lucida), and epazote (Dysphania graveolens), that are grown in mosaic. Each year, they alternate the crops so as to favor the vigorous plants. The cultivation of purple and white hyssops begins in April so as to harvest the aerial part of the plants (stem and inflorescence) in November. The rhizome sprouts stems, thus allowing another harvest in the next month of February. The first harvest produces a greater quantity of plants than the second one, resulting in a higher sale price in February.

In Santiago Mamalhuazuca, the purple and white house hyssops are grown in greater quantity than other medicinal plants, such as pericón, rue, etc. The major sale of bundles and consumption (in mixture) occur when the plants are in the floral stage.

In the mixed bundles, the greater portion consists of the house purple hyssop rather than white hyssop. The people explain that the latter “gives less,” that is that the plants are smaller and produced in lesser quantities, especially when drastic climatic changes occur during the growing season. Based upon response to inquiries about provenance of cultivated germplasm (that is inherited among parents, siblings, and extended families), it is estimated that they have been cultivating the two Mexican hyssops for approximately 100 years.

Morpho-physiological evidence

Discontinuities in the pattern of total variation and the clustering pattern

The evaluation of the 21 morphological characters in the 13 populations that include a total of 97 individuals reflects, in the UPGMA cluster analysis (Fig. 2), three groups: in the first group (I) are the three populations of A. palmeri, in the second (II) the three of the subsp. xolocotziana, while in the third (III) are the seven studied populations of A. mexicana. In this last group, two subgroups are observed, one that includes the four encouraged populations (V) and the other (IV) with the three cultivated.

UPGMA dendrogram of the evaluated populations of A. mexicana and A. palmeri. F encouraged, C cultivated, and T tolerated

The dispersion of the individuals in the PCA chart (Fig. 3) supports the grouping of the previous analysis. In the upper left quadrant of Fig. 3 are the individuals of A. palmeri. In the lower center are the individuals of A. mexicana (where the cultivated plants of this taxon tend to separate from those encouraged population). Finally, the subsp. xolocotziana is segregated in the upper right quadrant. The first two components explain 43.01 and 13.95%, respectively, of the total variance of the individuals evaluated.

Graph of the first and second principal component derived from the evaluation of 20 morphological characters in the 97 individuals evaluated. Table 2 shows the vectors with the highest weight in each component

Considering the characters with greater weight in the first component, the cultivated plants of both A. mexicana and the subsp. xolocotziana have larger size (length) in structures related to flowers (style (0.312), upper and lower stamens (0.314 and 0.313, respectively), tube (0.281), and flower (0.314)), and greater seed length. In addition, the subsp. xolocotziana displays a smaller number of teeth in the margin of the leaf (− 0.252), a smaller number of flowers (− 0.251), and smaller plants (− 0.244) when compared with the A. mexicana and encouraged plants tolerated from A. palmeri.

The characters with greater weight in the second component show that the subsp. xolocotziana have a smaller number of nodes in the stem (− 0.457), differentiation in the color of the flower (0.362/white flowers), and a greater length in the rhizome (0.325) when compared to A. mexicana and A. palmeri (Fig. 3, Table 2).

Significant differences and trends in domestication of A. mexicana (encouraged and cultivated plants)

Table 3 Averages and standard error of 12 characters that presented significant differences when comparing categories 1 (= encouraged) and 2 (= cultivated) in A. mexicana. Domestication trends that indicate these characters are presented

Five of these characters are related to reproductive structures. In cultivated plants, these characters suggest being related to gigantism in flowers and their greater pigmentation in them. With respect to the seeds, those of the cultivated form are larger than those of the encouraged form. These characteristics are very important in anthropocentric terms. Contrary to expectations, the cultivated Mexican hyssop has shorter inflorescences than the encouraged form.

Likewise, there are significant differences in two of three vegetative characters. The cultivated plants have larger leaves and a greater number of nodes in the rhizome than those of the encouraged plants. The differentiation in the leaves is related to a gigantism in the parts used. The difference in the rhizome suggests selection favoring greater asexual reproduction. However, total plant height of the cultivated Mexican hyssop is lower than that of the encouraged form.

Significant differences and trends in domestication in A. m. subsp. xolocotziana

When comparing the subsp. xolocotziana with its putative parents, A. mexicana (encouraged) and A. palmeri, 19 characters were found that differ significantly from the 21 characters evaluated in the study (Table 4).

Table 4 Means and standard error of 19 characters that presented significant differences when comparing the plants of (1) A. m. subsp. xolocotziana with (2) A. mexicana (encouraged) and (3) A. palmeri. Domestication trends of the subsp. xolocotziana are shown

All the reproductive characters evaluated had significant differences. They indicate that the subsp. xolocotziana has white flowers (in contrast to the pigmented flowers), and larger corolla, although fewer flowers per inflorescence. Flower size is a human-selected feature. The seeds of subsp. xolocotziana are larger; however, they have a low germination percentage. The seed gigantism may be a pleiotropic effect that is related to flower size.

Seven vegetative characters differed significantly. The plants of the subsp. xolocotziana are shorter, with smaller leaves and fewer teeth in comparisons to A. mexicana and A. palmeri. Very significant differences are found in the rhizome. The longer rhizome with more nodes affords greater asexual reproductive capacity. This feature is directly related to its management mainly through vegetative propagation.

Phytochemical evidence

Comparison of the chemical profiles of essential oils between the encouraged and cultivated plants of A. mexicana (Table 5) reveals that the former only present geraniol and pulegone, while the cultivated ones contain the five compounds evaluated: estragole, linalool, menthone plus the two cited above. All five compounds are present in the subsp. xolocotziana plants. In the case of A. palmeri, only three of them (geraniol, menthone, and pulegone) are registered (Table 5).

Table 5 Compounds, taxa, and management category considered in the study. (+) presence or (−) absence of the compounds


Domestication of Agastache

This study presents ethnobotanical, morpho-physiological, and phytochemical evidence about the domestication processes of A. mexicana and A. m. subsp. xolocotziana. On the one hand, this information shows a differentiation between the encouraged and cultivated populations of A. mexicana along the domestication gradient. On the other hand, subsp. xolocotziana diverged from one of its putative parents of hybridization (Table 6).

Organoleptic properties are fundamental in the plant domestication. Ankli et al. (1999b) and Brett and Heinrich (1998) reported that the organoleptic characteristics (mainly the aroma) of the plants are an important factor to determine them as medicinal, using them to define the relief ailment [18, 49]. Our work illustrates how these characteristics can also be fundamental in the process of domestication of aromatic medicinal plants, particularly in the hyssops. The people interviewed (Ozumba and Milpa Alta) recognize in A. mexicana an organoleptic differentiation between the plants encouraged, with a mild smell and flavor, and those cultivated, with an odor and sweet anise taste, relating the latter with greater effectiveness to alleviate different ailments, including gastrointestinal. At the same time, this is reflected in the phytochemical analysis where the cultivated hyssop has five aromatic compounds compared with the encouraged hyssop with only three aromatic compounds available (Table 5).

The morpho-physiological evidence indicates significant differences in floral, seed, and vegetative characteristics between the encouraged and cultivated plants of A. mexicana (Table 3). Flower size and corolla pigmentation were larger and more intense, respectively, in the cultivated populations. These characters are important selection criteria because the floral stage of Agastache is preferred state for consumption and is considered most effective as herbal remedy; hence, the cultivated category is the most appreciated.

Seed size was also larger in cultivated plants than in encouraged A. mexicana plants. However, ethnobotanical and physiological data show that this character is not directly selected. The interviewees mentioned that generally “all seeds germinate” and the physiological evaluation shows that there are no significant differences in the percentage of germination of the same; hence, the gigantism of this character is probably linked to the size of other related structures, possibly the largest size of the flower in cultivated plants.

As for the vegetative characters, the cultivated A. mexicana have a larger leaf size, a feature readily selected visually as being a valued trait of biomass yield. These characteristics were also found in the incipient domestication of cultivated epazote, selected for consumption as a condiment and as a medicinal herb [22]. Also, a greater number of nodes are found in the rhizome of the cultivated plants than those of the encouraged A. mexicana. This feature is related to its management, since vegetative propagation is preferred. Also, the increase of meristematic sites on the rhizome produces more stems that can be harvest.

In addition, significant differences were found in the total height and in the size of the inflorescence, being greater in the encouraged than in the cultivated ones of A. mexicana, opposite to the expected result, considering that those characteristics are subject to selection. These results may be associated with management, taking into account that the people interviewed mentioned that the plants developed from seeds in their first flowering period, “they do not grow much.” However, as time passes, the rhizome is strengthened and produces taller plants with larger inflorescences than those encouraged, explaining why the cultivation of these plants is mainly asexual.

When combining the three classes of evidence obtained in A. mexicana, a domestication syndrome is observed that consists of an organoleptic differentiation (smell and taste “sweet aniseed”) related to a phytochemical differentiation, floral gigantism, intensification of pigmentation, seed gigantism, and rhizome gigantism (enabling greater asexual reproductive capacity).

With respect to the origin of subsp. xolocotziana, the ethnobotanical, morpho-physiological, and phytochemical results clearly distinguish it from its putative parents, A. mexicana and A. palmeri, reflecting a series of domestication trends (Table 6). First, the organoleptic characteristics (mild mentholated) are very important for the traditional recognition of the subsp. xolocotziana in plantlet stage, since in its floral stage its differentiation is also based on the white color of the flower. The phytochemical differentiation is manifested by the presence of all five aromatic compounds analyzed (Table 5).

In morpho-physiological terms, flower color of the subsp. xolocotziana (white) was different compared to A. mexicana (purple) and A. palmeri (pink). Obviously, this trait is the basis of the folk nomenclature as well as recognition for selection during the floral stage and at the same time makes the plants more attractive to the consumer (Table 4 and Table 6).

The larger floral structures (size of the corolla, tube, style, and stamens) of the subsp. xolocotziana compared to A. mexicana (encouraged) and A. palmeri indicate gigantism in the flower (Table 4). Gigantism in this structure was also found in the cultivated plants of A. mexicana. In both taxa, the flowers are subject to selection, since they are a very important character for their medicinal consumption, where they are used together to potentiate their calming effect, as well as recognition by consumers [13, 31, 40].

Contrary to expectations, inflorescences of subsp. xolocotziana are smaller size (due to fewer number of nodes and of flowers) compared to their putative parents (Table 4). Some vegetative characters, such as the total height and area of the leaf (linked to a smaller number of teeth on the leaf) were also found to be reduced in this subspecies. Probably, as in the case of cultivated plants of A. mexicana, this is due to the plants being produced by seeds that reached only their first flowering period under experimental conditions. However, the people interviewed mention that of the harvest of subsp. xolocotziana is less than that of cultivated A. mexicana. It may be that dwarfism in these plants may represent depression.

The seeds also present gigantism in the subsp. xolocotziana; however, they are partially sterile, given the low percentage of germination found (30%) and the ethnobotanical information registered. In this sense, the gigantism in this structure is not related to its viability but may be linked to the gigantism present in the flower.

The rhizome-related characters in this subspecies also show significant differences when compared to the other two taxa, indicating gigantism with its longer rhizomes with a greater number of nodes (Table 4). These features are directly related to its management. Not only do these rhizomes facilitate rapid, one-step vegetative planting but also permit greater production of harvestable stems. A similar result was observed in cultivated plants of Manihot esculenta in which there was a greater production of propagules compared to their wild relatives [55].

The domestication syndrome of the subsp. xolocotziana combines elements of organoleptic and phytochemical differentiation, floral gigantism, floral albinism, seed gigantism, and rhizome gigantism. This latter feature offsets the disadvantage of seed sterility so as to favor cloning of a novel, desirable form of Agastache.

The morpho-physiological evidence shows a divergence of A. mexicana (encouraged) toward the subsp. xolocotziana (Fig. 3). Two major explanations may account for this situation. On the one hand, inbreeding depression in the typical A. mexicana may have given rise to the subsp. xolocotziana. In the populations of plants where disruptive evolutionary force operates, divergence can produce populations with lower fitness, which is expressed in its reduced vigor and fertility [56, 57]. These particularities are reflected in this taxon with less vigorous structures, lower germination percentage, and lower number of flowers produced (Table 4).

On the other hand, Abbott et al. [58] (2013) report that hybrids may not be morphologically and genetically intermediate to their parents, since one parent is dominant that it is difficult to detect the other in the hybrid. In this sense, this work does not rule out the hypothesis of the possible hybrid origin of the subsp. xolocotziana, since possibly A. mexicana has a morphological and genetic dominance over this subspecies.

In phytochemical terms, hybrids usually present additive, shared, and new compounds [59]. Based on this, the subsp. xolocotziana shows additivity in the menthone compound, and two shared compounds geraniol and pulegon with the possible parents (Table 5). In addition, Estrada-Reyes et al. (2004) reported the presence of 27 new compounds in the subsp. xolocotziana when compared with A. mexicana. It should be noted that in our work it was not possible to detect more compounds by the method used (TLC). Another novel character in this taxon is the white color of the flower; this particularity for instance has been found in the flowers of strawberry hybrids (Fragaria sp.) [60]. Also, partially sterile seeds are a trait of plants with a hybrid origin [61].

In order to clarify the origin of subsp. xolocotziana, phytochemical (more detailed gern technique) and genetic (phylogenetic and population genetics) studies of plant populations studied will provide more specific information about these two hypotheses.

Maintenance strategies of cultivated germplasm

As for the encouraged populations of A. mexicana, they are found only on the periphery of the milpa agroecosystem, because in these places the inhabitants foster, maintain, and select “toronjil” for domestic use (medicinal and esthetic). Our study did not locate wild populations of this taxon in sites where it grew in 1980s [29]. Hence, the traditional management that the inhabitants of Milpa Alta provide in their milpa is as an important conservation mechanism for the permanence of this species.

In addition, the introduction of plants originating from seeds of A. mexicana crops is an important management and conservation strategy for these populations, since it has been reported that this practice helps maintain and generate genetic variability in vegetatively propagated crops [55, 62, 63].

Our ethnobotanical research indicates that the subsp. xolocotziana has high sensitivity to extreme environmental changes. Considering that it is known only from cultivation of mostly clonal plants, and that it exhibits partially sterile seeds, favoring the most vigorous individuals produced from seeds is fundamental for the conservation of this taxon. Several studies have documented that this type of management in vegetatively propagated crops can significantly increase their genetic diversity, making crops more resistant to environmental changes, such as agaves (Agave angustifolia Haw.) and cassava (Manihot esculenta Crantz) [55, 63,64,65].


The evidence obtained indicates two divergent evolutionary processes under domestication. First, populations of A. mexicana growing in central Mexico are positioned medially along the domestication gradient and express elements of a domestication syndrome including organoleptic differentiation related to a phytochemical differentiation, floral gigantism, pigment intensification, seed gigantism, and rhizome gigantism. Second, A. m. ssp. xolocotziana, possibly originated by inbreeding depression or hybridization, demonstrates a syndrome with organoleptic and phytochemical differentiation, floral gigantism, albiflorism, seed gigantism, and rhizome gigantism. Each process has distinctive elements that make up its domestication syndrome which coincide with their importance in MTM to impart a calming effect in treating various ailments.