The botanical identification ofUlluchu, an iconic fruit frequently depicted in the art of the pre-Columbian Moche culture that flourished from A.D. 100–800 on the Peruvian north coast, has eluded scientists since its documentation in ceramics in the 1930s. Moche fine-line drawings ofUlluchu normally depict seed-pods or seeds floating in the air in sacrificial scenes, associated with runners and messengers or intoxicated priests. It is a grooved, comma-shaped fruit with an enlarged calyx found mainly in fine-line scenes painted on Moche ceramics. The term first appeared without linguistic explanation in the work of pioneer Moche scholar Rafael Larco Hoyle, and the identification of the plant was seen as the largest remaining challenge in current archaebotany at the Peruvian North coast. The nameUlluchu seems to have been coined by Larco. According to his description, the name originated in the Virú River valley, and is supposedly of Mochica origin. However, there is no linguistic evidence that such a term indeed existed in the Mochica or Yunga language.

We conclude thatUlluchu can be identified as a group of species of the genusGuarea (Meliaceae) based on morphological characteristics. In addition, the chemical composition of the plant's compounds supports the thesis that it was used in a sacrificial context to improve the extraction of blood from sacrificial victims. We also suggest that a ground preparation ofGuarea seeds, when inhaled, may have been used as a hallucinogen. However, more detailed phytochemical research is needed to corroborate the latter hypothesis.

Ulluchu is the common name assigned to a plant frequently depicted in the art of the Moche culture, which thrived on the north coast of Peru from A.D. 100 to 800. It is a grooved, comma-shaped fruit with an enlarged calyx found mainly in fine-line scenes painted on Moche ceramics. The term first appeared without linguistic explanation in the work of pioneer Moche scholar Rafael Larco Hoyle ([1] Fig. Fifty-eight: [2] Fig. Ninety-eight, Figs. One hundred and sixty-six and sixty-seven). In his 1939 publication, he reported that the peoples of the sierras and the coastal region (Viru and Moche valleys) believed that the fruit had to be picked silently to prevent it from turning bitter. He wondered if the plant symbolized the silence and discretion of richly attired Moche messengers, some of whom wear belts adorned withUlluchus. In his 1938 publication, he labeled a Moche fine-line drawing ofUlluchu asPhaseolus sp. (a bean). Larco clearly recognized thatUlluchu had nothing whatsoever in common with "ulluco" (Ullucus tuberosus), an Andean tuber still widely cultivated and consumed in Peru nowadays.

The symbolic importance ofUlluchu in Moche iconography was firmly established by Moche scholar Donnan McClelland [3]. Based upon a meticulous review of the UCLA Moche Archive, she showed that its distribution was non-random and that its varied usage displayed definite patterns with the greatest variability among background elements and the most frequent representation found on the belts of warriors and runners. She demonstrated that "the leaves of thePhaseolus do not resemble theulluchu leaf depictions" [[3]: 43].Pepino (Solanum muricatum) andaji (Capsicum annum), which are clearly depicted in Moche art and do not resembleUlluchu were also eliminated "since theulluchi [sic] fruit is suspended from the plant by its smaller pointed end, whereas these two are suspended by the large end" [[3]: 437]. She also indicated that the plant had not been botanically identified, pointing out that, if it turned out to be a mythical plant, no identification would be possible.

A decade after McClelland's seminal article, S. Henry Wassen [4] of the Gothenburg Ethnographical Museum, eliminatedPersea americana Miller var.americana (a wild relative ofavocado) as a candidate, and concluded thatUlluchu wasCarica candicans A. Gray (a species of wildpapaya). He also co-authored an article describing the enzyme papain, which can be extracted from unripe papaya, for use as a blood anti-coagulant [5]. In the latter article, the authors proposed that papain was used in the Moche sacrifice ceremony to prevent the coagulation of blood drawn from sacrificed warriors for later consumption by priests.

In a paper presented at the Sibley Conference at the University of Texas at Austin, in November 2003, McClelland [6], in addition to updating her 1977 paper in the light of a vastly expanded Moche Archive and archaeological discoveries of realUlluchu, refuted the papaya hypothesis. She also discussed the presence in the art of yellow oleander seeds (Thevetia peruviana) as legging rattles as well asespingo seeds (Nectandra sp.) which [7] had earlier suggested might have been added to corn beer for medicinal and psychotropic purposes. McClelland concluded that the largest remaining challenge was the identification ofUlluchu.

In the present paper we build on the work of Donna McClelland and the archaeological excavations at Sipán in the Lambayeque Valley [8,9] and at Dos Cabezas in the Jequetepeque Valley in the 1990s [6].

The primary focus of this project has been the ethnobotany of medicinal plants used in Northern Peru and Southern Ecuador, and the changes that have occurred since early colonial times. Fieldwork for the present study was conducted in Southern Ecuador from 1995–2000, and in Northern Peru from 2001–2008. In the course of the fieldwork vouchers of all useful plant species sold in the markets of the region were collected after establishing prior informed consent. The specimens were registered under the collection series "RBU/PL," "ISA," "GER," "JULS," "EHCHL," "VFCHL," "TRUBH," and "TRUVANERICA," depending on the year of fieldwork and collection location. Vouchers of all specimens were deposited at the Herbario Truxillensis (HUT, Universidad Nacional de Trujillo), and Herbario Antenor Orrego (HAO, Universidad Privada Antenor Orrego, Trujillo). In order to recognize Peru's rights under the Convention on Biological Diversity, most notably with regard to the conservation of genetic resources in the framework of a study treating medicinal plants, the identification of the plant material was conducted entirely in Peru. No plant material was exported in any form whatsoever. The nomenclature of plant families, genera, and species followed theCatalogue of the Flowering Plants and Gymnosperms of Peru [10] and theCatalogue of Vascular Plants of Ecuador [11]. The nomenclature was compared to the TROPICOS database. Species were identified using the available volumes of theFlora of Peru [12], as well as [13,14] and reference material in the herbaria HUT, HAO, QCA, LOJA, and QCNE.

In addition to documenting the associated use-knowledge, plant collectors, vendors andcuranderos (local healers) were interviewed about any possible knowledge ofUlluchu. Also, colonial records about useful plants of the region, which include [15–21] were searched for possible information and iconography of the plant. Photographs of all archeological specimens found, including photographs of the interior fruit structure in broken specimens, were obtained and used for direct comparison to botanical vouchers and life specimens of plant candidates. Ultimately, the available online collections of the Chicago Field Museum, New York Botanical Garden, and Missouri Botanical Garden were checked for possible candidates, and specimens from the Missouri Botanical Garden Herbarium were used for final determination and imaging.

Issues surrounding the nameUlluchu

The nameUlluchu seems to have been coined by Larco [1]. According to his description, the name originated in the Virú River valley, and is supposedly of Mochica origin. However, there is no linguistic evidence that such a term indeed existed in the Mochica or Yunga language. The most comprehensive Mochica-Spanish dictionary available, compiled from the writings of Moche scholar E. Brüning [22], has no such term. In addition, the local population, as well as market vendors, plant collectors, andcuranderos interviewed, had no knowledge ofUlluchu whatsoever, other than what they derived from Larco. Since this first publication the term has been copied by all subsequent authors [e.g. [3,4]], without any regard to its validity. It is unlikely that Brüning [22] would have missed the name when doing his research early in the 20^th century, if it indeed was still being used. Brüning lists quite a few Mochica plant names, some of which are still used for the same plants today, e.g. "faik" =Acacia macracantha (faique, espino), from "fáçek, fáçke" = spine.

The only language that has a somewhat similar word from whichUlluchu could be derived is Quechua: "uchu" translates to "chili, pepper," while "ullu" translates as "penis." The term "ullu uchu" is sometimes used as a name forColumellia ovata R. & P. (Columelliaceae), a small high-Andean plant, described as "a very thick tree; its wood is suitable for various purposes, and its leaves have febrifugal properties and are very bitter" [21]. However, this plant has no likeness whatsoever to the MocheUlluchu. Thus we must conclude that the termUlluchu was most likely coined by Larco [[2]: 98] based on a Quechua term for a species with somewhat similar fruits that has no relation to the species used by the Moche.

Botanical identification

Why isUlluchu notCarica candicans?

Carica candicans is a wild relative of papaya (Carica papaya L.). Although the fruits are not marketed, they are occasionally consumed by the local population, and some market vendors and healers interviewed did know the plant under its vernacular name, "mito." Larco [1,2] never mentions the plant in relation toUlluchu. Assuming that he indeed encountered a plant with that name, it cannot have beenC. candicans, because this species would have been named "mito."

McClelland [6] argues thatUlluchu "cannot be a papaya, which belongs to a group of plants called 'cauliflory' [i.e., stem flowery]. ... The flowers and fruit of a cauliflory grow on the trunk of the tree and not on the limbs. ...Ulluchus depicted in Moche art, however, hang from limbs. Papaya leaves do not resembleulluchu leaves, which are triangular, ovoid, or boomerang shapes hanging from limbs. Each large palmate papaya leaf grows on a stem from the top of the tree." However, further complicating this matter, it turns out thatC. candicans happens to be one of the few papayas that are not cauliflorous, that have triangular leaves with entire margins, and the fruits do hang from branches. Thus, judging from the iconography alone,C. candicans actually could beUlluchu.

Based on recent archaeological evidence however, [6,8,9,23], it has become clear that the actual fruits found in burials do not resembleC. candicans. In addition, the explanation that papain, might have been extracted by the Moche from unripe papaya for use as a blood anti-coagulant [5], albeit reasonable, does not make much sense from a phytochemical perspective. Cultivated papaya (C. papaya) is often depicted in Moche pottery, and the species contains large amounts of papain. Why would the Moche have resorted to a rare wild species, when they could have used a cultivar with the same properties that grew on their very doorstep? Also,C. candicans fruits are often 10–15 cm. long, and, while this would relate to the size of some of theUlluchus in the iconography, it is vastly larger than many of the fruits depicted and much larger than the fruits found in burials. Finally, the anatomy ofC. candicans simply does not correlate with the fruits encountered in burials.

What isUlluchu, and what was it really used for?

Moche fine-line drawings ofUlluchu normally depict seed pods or seeds floating in the air in sacrificial scenes (e.g., [6] Fig. Three.14), associated with runners and messengers (e.g., [6]: Fig. Three.1) or intoxicated priests (e.g., [6]: Fig. Three.6). TheUlluchu fruits vary greatly in size, ranging from about 1–15 cm. They are normally comma-shaped, often with an "exaggerated round calyx" [[6]: 43] with lines on the body of the fruit (e.g., [6]: Fig. Three.4). Some illustrations showUlluchu harvested by monkeys, and in such cases the fruit is mostly shown growing along the axes of the plant's leaves (e.g., [6]: Figs. Three.27 & Three.28).

Starting from this basis in 2002, we built on the work of Donna McClelland and the archaeological excavations at Sipán in the Lambayeque Valley [8,9,24] and at Dos Cabezas in the Jequetepeque Valley in the 1990s [6,23]. Botanically, all these depictions resemble capsules or drupe-like fruits. It became apparent that in a biodiversity hotspot like Peru, with a flora of more than 18.000 species, a large number of plant families have fruits that vaguely resemble Moche fineline drawings ofUlluchu, and many of these families contain more than one genus with similar fruits. Examples include: (Apocynaceae:Ambelania; Caricaceae:Carica; Celastraceae:Maytenus; Chrysobalanaceae:Chrysobalanus,Hirtella,Licania; Convolvulaceae:Dicranostyles; Fabaceae:Aldina,Alexa,Andira,Dipteryx,Dussia,Ormosia; Guttiferae:Tovomita; Hippocrateaceae:Cheiloclinum,Salacia; Icacinaceae:Calatola; Meliaceae:Guarea; Menispermaceae:Abuta,Curarea,Elephantomene,Telitoxicum; Myristicaceae:Virola; Olacaceae:Cathedra; Quiinaceae:Lacunaria; Sabiaceae:Meliosma; Sapindaceae:Cupania,Paullinia; and Sapotaceae:Pouteria. Some of these are still highly important in traditional societies. For example,Ambelania fruit is often consumed;Ormosia contains potent poisonous compounds, but is now mostly used in crafts;Curarea is one of the ingredients of "curare," the famous Amazonian arrow poison;Virola species are still used as potent snuffs in the Amazon; andPaullinia is the source of "yopo," an important stimulant. However, none of these carry the vernacular nameUlluchu.

Fortunately, at this time the archaeological evidence provides good clues for identification. TheUlluchu fruits found in burials in the 1990's are clearly capsules or drupes, slightly comma-shaped, between 1.5 and 5 cm. long, and slightly grooved (Fig.1A&1B). They closely resemble bone, gold, andSpondylus beads foundin situ in size, form, and texture (Fig.1C–E). In the iconography, the fruits are often depicted on both sides of branches, as in the headdress of Fig.1F. It is important to note that this figure has widely extended nostrils, as is often seen in people inhaling hallucinogenic snuffs, and is holding a gourd and pestle. McClelland ([6]: Fig. Three.18) interpreted this as lime gourd used for chewing coca. We suggest that this might also be a gourd used to grind the seeds ofUlluchu for inhalation. Further iconographic evidence supports this hypothesis. Runners and messengers associated withUlluchu are often winged – they literally fly, i.e., the inhalation ofUlluchu gives them wings. An excellent example is the runner depicted in Fig.1G: The personage hasUlluchu on his belt,Ulluchu seeds floating above its head, and an instrument in his hand that closely resembles a typical double snuff tube that would serve to inhale powdered hallucinogenic substances. Thus, it seems possible that one of the uses ofUlluchu may have been as a mind-altering snuff. Another reason for identifying the seeds in the iconography as hallucinogenicUlluchus is underscored by Fig.1H: This is part of a famous Moche scene (see [6]: Fig. Three.34) where monkeys are picking fruits from anUlluchu tree. It is important to note that the tree depicted has opposite leaves and that seeds are extracted from the fruit, possibly for roasting in a typical oven on the bottom right. The roasted seeds could then be ground to powder and inhaled. The fruits themselves seem to be 5-valved. The function ofUlluchu as a hallucinogen is reinforced by other imagery (e.g., [6]: Fig. Three.6), where personages, surrounded byUlluchu fruits lie on the ground in what clearly appears to be an intoxicated state. In addition, prisoners in sacrificial scenes (e.g., [25]: Figs. Two.2, Two.3, Two.12 & Two.24), especially the well known "lines of prisoners" at Huaca El Brujo and Huaca de la Luna (Fig.2) all show clearly visible erections, which may be seen as another indication of the ingestion of some substance causing this effect. From this perspective Larco's termUlluchu [2], if derived from Quechua "ullu-uchu" – "penis pepper," would in fact make sense in describing the possible effects of the plant in question. Also, the association with sexual arousal is reinforced by mythical scenes where anUlluchu tree grows out of the back of an erotic couple.

Ulluchuin archaeological context. A.Ulluchu fruit from cache at Sipán. After photograph by Christopher B. Donnan. B.Ulluchu fruit from Dos Cabezas burial. After photograph by Donald McClelland. C. Bone beads in form ofUlluchus fron Huaca de la Luna. After photograph by Donald McClelland. D. GoldenUllucho bead. After photograph by Donald McClelland. E.Spondylus shell bead in form ofUlluchu. After photograph by Donald McClelland. F. Supernatural figure seated holding a gourd, possibly containing groundUlluchu seeds withUlluchus painted on headdress. Private collection. After photograph by Christopher B. Donnan, in McClelland ([6]: Fig. Three.18). G. Anthropomorphized hawk runner carrying a snuff tube withUlluchus on its belt andUlluchu seeds floating above it. The Art Institute of Chicago. After drawing by Donna McClelland in McClelland ([6] Fig. Three.12). H.Ulluchu harvest. Note tree with opposite leaves and extracted seeds on bottom right. After McClelland ([6]: Fig. Three.34), Private collection.

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Line of prisoners at Huaca El Brujo. Photo by Rainer W. Bussmann.

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In light of the above,Ulluchu is a tree with opposite leaves and fruits that are drupes between 1–15 cm long possibly containing active ingredients that would elevate the blood pressure and cause erections, and psycho-active substances. The only plant family from the list above having representatives that meet all these criteria is Meliaceae, and the genusGuarea is the one that most closely fits the description. It includes mostly trees with pinnate leaves (which is unusual for Meliaceae), and fruits that are 3–5 valved capsules, with large, pseudo arillate seeds. The genusGuarea is found throughout Peru, but is mostly restricted to tropical lowland forests, with some species reaching cloud forest habitat. No species is found along the dry coast of Peru, which indicates that the material must have been widely traded in Moche times. A typical representative isGuarea grandifolia DC. The species has clearly pinnate leaves (Fig.3A), and the fruits (Fig.3C) very clearly resemble the archaeological samples depicted in Fig.1. In addition,Guarea contains a large number of species with varying fruit sizes (from 1–15 cm.), calyx swelling, and grooving on the body of the fruit (Fig.4), which all correlates with the variedUlluchu imagery in Moche fineline drawings. The seeds ofGuarea species, with a distinct white navel, very much resemble the seeds depicted in Moche fineline paintings.

Guarea grandifolia. A. Mature branch. B. Flower. C. Mature fruit. D. Fruit cross section. E. Seeds F. Branching pattern.

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Fruits of various species ofGuarea(G. macrophyllawith seeds,G. carapoides,G. carinata,G. macrophylla,G. purusanawith seeds,G. guentheriwith seeds).

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Many species ofGuarea are known by a wide variety of vernacular names, e.g.,Guarea spec.: requia, kushímsakish;G. glabra: yecheñor, yechemor;G. grandifolia: bola requia;G. guidonia: atapio, latapi, latapi caspi, requia colorada, requia latapi, xoro;G. kunthiana: requia, paujil ruro;G. purusana: latapi, requia). The wood of many species is used as timber for construction. The wood, bark, and leaves contain compounds that act as abortive, emetic, purgative, and antiamoebiac agents, and the bark is often sold asCoccilliana in expectorant preparations [12,26–28]. The fruits and seeds contain a variety of alkaloids that are very rarely used due to their high toxicity [29]. Some of the alkaloids found, e.g. rusbyine, have a structure and effects like emetine, an alkaloid found inPsychotria ipecacuanha (Brot.) Stokes, which has been widely used as an emetic and expectorant. Other species ofPsychotria are well known as components inayahuasca preparations due to their high content of N,N-DMT [30]. In large dosages,ipecac preparations cause high blood pressure, arrhythmia, spasms, and extension of the blood vessels. While the existing literature onGuarea seed compounds is rather fragmentary, it seems clear that a concentrated dosage ofUlluchu seeds, if ingested, would increase a prisoner's heartbeat, elevate the blood pressure, and widen blood vessels thus causing erection. All of this would make it much easier to extract sacrificial blood. Also, when inhaled by priests, the active compounds could have a mind-altering effect, which would not necessarily lead to high levels of toxicity, and could induce very rapid, short-term hallucinations.

We conclude thatUlluchu can be identified as a group of species of the genusGuarea (Meliaceae) based on morphological characteristics. In addition, the chemical composition of the plant's compounds supports the theses of [3,4] that it was used in a sacrificial context to improve the extraction of blood from sacrificial victims. We also suggest that a ground preparation ofGuarea seeds, when inhaled, may have been used as a hallucinogen. However, more detailed phytochemical research is needed to corroborate the latter hypothesis.

Manuscript in memory of Donna McClelland.

The present study was financed through MIRT (Minority International Research and Training) or MHIRT (Minority Health Disparity International Research Training) as it was recently renamed, a grant from the National Institutes of Health (Fund: 54112B MHIRT Program, Grant: G0000613), initially administered by the Fogarty International Center for Advanced Studies in Washington, D.C. MHIRT-Peru is coordinated by San Diego State University (SDSU) in cooperation with the San Diego Museum of Man (SDMOM), the P.A. Hearst Museum of Anthropology at the University of California Berkeley (PAHMA-UCB), and the University of Hawaii at Manoa in the US, as well as the Universidad Privada Antenor Orrego (UPAO, Herbarium HAO), the Universidad Nacional de Trujillo (UNT, Herbarium HUT and Instituto de Medicina Tropical) and the Clínica Anticona Trujillo (CAT) in Peru. We owe a great debt of gratitude to Donna McClelland, who unfortunately did not live to see the solution to the riddle that she worked on for decades. Special thanks go to Christopher Donnan and Don McClelland for putting us on the track ofUlluchu and supplying photographs of all of the archaeological evidence available. Finally many thanks to Barbara Alongi at MBG, who provided the detailed drawings for Figures1,3, and4.

Authors and Affiliations

1. Missouri Botanical Garden, William L Brown Center, PO Box 299, St. Louis, MO, 63166-0299, USA

   Rainer W Bussmann

2. 2328 Dolphin Dr, Richmond, CA, 94804, USA

   Douglas Sharon

Corresponding author

Correspondence toRainer W Bussmann.

Declaration of Competing interests

The authors declare that they have no competing interests.

Authors' contributions

Both authors share the contributions to fieldwork, data analysis, and compilation of this manuscript. All authors read and approved the final manuscript.

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