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Chamal (Dioon edule Lindl.) in the State of San Luis Potosí, México Laura Yáñez-Espinosa* INTRODUCTION many D. edule populations, because the (0.1% fresh weight) and macrozamin (0.6% pproximately 20% of world cycad species is considered extremely toxic to fresh weight) in Dioon edule seeds and Aspecies are found in Mexico, 80% animals, and exterminating these plants is concluded that the seeds are highly toxic of which are endemic (Vovides, 2000). considered an effective option to prevent for rodents. At least nine species are present in the harm to livestock. One portion of the Huasteca region is state of San Luis Potosí: Dioon edule, According to the farmers, cattle con- inhabited by the indigenous Xi’iuy people, Zamia fi scheri, Z. loddigesii, Ceratoza- suming young leaves or cones is fatal; whose major activity is agriculture, based mia hildae, C. kuesteriana, C. latifolia, the effects start with diarrhea, progress on cultivation of maize, beans, and sugar C. mexicana, C. microstrobila, and C. to paralysis of the hind legs, and fi nally cane. Hunting does not represent a major zaragozae (Yáñez-Espinosa, 2006) [Ed’s result in death. This could be attributed source of food, but gathering products, note: Zamia vazquezii is also found in to toxic secondary metabolites produced like maguey (Agave spp.) and chamal San Luis Potosi]. Dioon edule LINDL. is the in cycads that apparently serve as protec- (Dioon edule) derivatives are consumed. most widely distributed, particularly in tion against predators. Although it has The harvest of chamal has played a major the Huasteca zone located in the Sierra been suggested that these compounds role in the Xi’iuy diet from time imme- Madre Oriental. Habitat deterioration of are responsible for the control of devel- morial, since this is a substitute when D. edule is evident, since many natural opment and maintenance of herbivores maize and bean yields are low. It is com- forests have been converted into either associated with cycads, two of these mon for the Xi’iuy to consume tamales, pastureland for cattle or sugarcane fi elds. compounds, cycasin and macrozamin, can gorditas, and tortillas made from chamal, Cattle breeding has been devastating for cause severe intoxication in addition to the dough made from boiled and ground ______________ carcinogenic and neurotoxic effects in seeds. Some recipes alert the maker that *Universidad Autónoma de San Luis Potosí, Instituto de Investigación de Zonas Desérticas mammals (Schneider et al., 2002). One improperly prepared chamal foodstuffs Altair 200, Col. del Llano, 78377 San Luis Potosí, study has reported low values of cycasin may cause vomiting, gastrointestinal dis- S.L.P., México a c b d Fig. 1. (A) Dioon edule population located in a well conserved habitat; (B) land conversion to agriculture conserving few individuals of D. edule; (C) leaf herbivory by Eumaeus childrenae caterpillars;(D) D. edule population damaged by fi re when Opuntia plants were established. The Cycad Newsletter 32(2/3) June/September 2009 Page 18 ease, or “fatal consequences” in people The following sections represent the crowns. Adult individuals were classifi ed when consumed (Bassler, 2000). results of three separate investigations as male or female from observation of the Besides the common use of chamal as that were conducted to address these mature or immature cones, or their ves- a food source, it also has medicinal, or- three questions. They were written inde- tiges, on the stem. namental, and other uses. Our research pendently, and each has its own title and Analyses of the soil sampled from the approach to study chamal was multidis- authors. six sites indicated that Dioon edule has a ciplinary, and the proposal included eco- preference for clay soils consisting of over logical, ethnobotanical, and toxicological Population Structure of Chamal 50% clay particles, 17% organic matter, investigations. We were aware that this G. Rubio Méndez, R. Mora Cardona and a slightly basic pH (average pH = 7.2). would be a long-term project, but our ex- & L. Yáñez-Espinosa This soil, because of its density, retains periences by the end of the fi rst year in- Preliminary exploration of an altitude moisture well and tends to be more nutri- clude benefi ts like the promotion of con- gradient (400, 1000 and 1200 m above sea ent-rich than other soil types. The aver- servation of existing populations of Dioon level [masl]) in San Luis Potosí indicated age calcium content of 82.43 meq 100g-1 is edule, a species that is poorly known in an abundance of Dioon edule plants, as very high, and the soil is slow-draining and the state of San Luis Potosí; compilation well as a high frequency of use of chamal compacts easily (Barnes et al., 1998). of traditional knowledge of the Xi’iuy for food, medicine, and ornamental and We found two populations of Dioon people related to this species; and ex- trade objects. Planned fi eld routes were edule with conditions of well conserved ploration of possible toxic effects of the traversed in the company of male key in- habitat of high quality. There were two seeds of this species as a food source. formants that were selected on the basis populations with intermediate quality Thanks to the Cycad Society grant in 2007, of their knowledge, leadership, and moral habitat and intermediate plant density, we were able to carry on the research, infl uence on their communities, as well as and two populations with low quality with complementary funds and infrastruc- their willingness to cooperate with us. habitat, mainly caused by cattle and land ture provided by the Autonomous Univer- Six selected sites were located with conversion to agriculture (Fig. 1). In the sity of San Luis Potosí, and collaboration GPS, and the habitat in each was char- six sites, most of the Dioon edule plants of three B.Sc. students from three dif- acterized by defi ning vegetation type, showed signs of herbivory by Eumaeus ferent disciplines—agronomy, geography, fl oristic composition, soil characteristics, childrenae (Lepidoptera: Lycaenidae) and chemistry—that worked together to and threats, such as deforestation, fi re, caterpillars, that have been previously develop the research project. cattle incidence, and others. Dioon edule reported for the Huasteca region (Contre- The study area comprises the munici- population structure and spatial distribu- ras-Medina et al., 2003). palities of Tamasopo, Rayón, and Santa tion was characterized in two sampling Species richness in the high-quality Catarina in the Huasteca region. These transects of 100 m length by 2 m width. habitats—distributed in the ecotone of were selected to carry on the research Plants intercepted in each transect were submontane shrubs and Quercus forest— based on previous knowledge of the utili- counted and their heights and diameters was high and included Flourensia lau- zation of chamal by the Xi’iuy people. We measured; also assessed were the number rifolia DC. (Asteraceae) and Quercus of leaves per plant and the life stage. stated three main questions, as follows: polymorpha SCHLTDL. & CHAM. (Fagaceae). In Dioon edule life stages were classifi ed as: the lower quality habitats—distributed in 1) What is the situation of the natural 1) seedlings – individuals with no visible the ecotone of submontane shrub and dry populations and habitat of Dioon edule? stem, one to few leaves not arranged in tropical forest—were Bursera simaruba a crown; 2) juveniles - non-reproductive 2) What and how many ethnobotanical (L.) SARG. (Burseraceae) and Pseudobom- individuals with no visible stem or barely categories can be recognized for Dioon bax ellipticum (KUNTH) DUGAND (Bomba- edule plants? visible, and leaves arranged in one or caceae). 3) How can toxins present in the seeds of more well-developed crowns; and 3) All populations showed a low fre- Dioon edule affect the Xi’iuy people adults - reproductive individuals with quency of female adults (Table 1), but it that eat them? a visible erect stem and one or more is interesting that populations inhabiting conserved habitats were located closer to Xi’iuy indigenous communities, and less conserved habitats were farther away from Xi’iuy communities. Ironically, fe- male cone harvest pressure is higher in the closer populations. The sex ratio in the medium and highly conserved habi- tats averaged 2:1 (M:F). Populations from more distant habitats have cattle pres- ent, and all plants in the population are b threatened in order to avoid toxic dam- age. Seedlings and juveniles showed a low frequency in the lower quality habitats, and the sex ratio was of 1.4:1. We also evaluated cone and seed devel- opment, seed production, and sporophyll morphology in 13 mature female cones harvested from two sites authorized by the Mexican government (SEMARNAT No. a c 00507/08) (Fig. 2). Average weight of female cones was 1.4 kg, and the aver- Fig. 2. (A) Female cone of Dioon edule being weighed and (B) dissected; age number of sporophylls was 220, with (C) sporophylls with attached seeds removed for characterization. an average of 180 well-developed seeds. The Cycad Newsletter 32(2/3) June/September 2009 Page 19 These seeds were sowed last July 2008 in regulate its use with the aim of conserving for grinding corn) to produce a dough. The greenhouse conditions to evaluate germi- populations without detriment of every- tamales are small dough balls of 4-7 cm, nation, but this process has not fi nished. one’s benefi t. plain or fi lled with egg or chickpea stew, Food processing of chamal seeds must and occasionally wrapped with leaves of Alimentary Uses of Chamal be done correctly to avoid symptoms like Arundo donax L. Finally, the tamales are E. Tristán Martínez & J.

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