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Description:
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Astrophytum asterias (star cactus ) and Lophophora williamsii (peyote ) are sympatric species in the Tamaulipecan thornscrub of South Texas and adjacent Mexico . Peyote has been excavated from two archaeological sites : Shumla Caves , Texas , and CM -79 in Coahuila . We report new radiocarbon dates : a mean of 5195 à ± 20 14C years BP for the Shumla Caves specimens , and 835 à ± 35 14C years BP for the CM -79 specimen . The Shumla Caves specimens were not intact peyote tops , but manufactured effigies thereof . Published data on the geographic ranges of L . williamsii and A . asterias are of varying quality and accuracy . We report the results of extensive research to document extant U .S . populations by county , drawing specific conclusions about where each species currently occurs , where its occurrence is uncertain and where it is unlikely , based on herbarium specimens , verifiable reports in the primary literature and interviews with knowledgeable individuals . Dwindling of populations of peyote is partly due to improper harvesting , namely cutting off the top of the plant so deeply below ground level that the plant is unable to regenerate new stems , and consequently dies . We describe the anatomy of the cactus shoot (stem ) and root , and suggest how this new knowledge can be utilized to determine "how deep is too deep" to cut if harvesting of peyote is to be done sustainably . We report the first population genetics study on endangered A . asterias , with five microsatellite markers in populations sampled at four locations in South Texas . A battery of tests and measurements indicated that in most populations heterozygosity was high , F -statistics were low , and Nm was >1 . With one exception , these populations appear not to be undergoing excessive inbreeding , despite small population sizes . Data from two L . williamsii microsatellite loci are presented . L . williamsii , which reproduces autogamously , exhibits a single homozygous genotype within a given population . West Texas L . williamsii plants differ from South Texas plants in the identity of the single allele (or single genotype ) at each locus . The ability of microsatellite markers to separate West Texas from South Texas plants suggests utility of microsatellites for infraspecific taxonomic studies in Lophophora . |