microhabitat conditions result normally in the development of 

 relatively large, thin leaves with reduced numbers of stomata 

 and veinlet termini per unit area, as well as more slender and less 

 conspicuous veins. Conversely, sunny and drier habitats induce 

 the formation of small and thicker leaves with comparatively 

 more numerous stomata and veinlet termini, and more prom- 

 inent, thicker veins. Shade-leaf morphology appears not only in 

 South American coca plants grown under shaded conditions, 

 but also in plants of each variety cultivated under glass at 

 temperate latitudes in North America (Rury, 1982; Plate 39D, 

 E). Due to this habitat-related plasticity in the structure of coca 

 leaves as well as their intergrading patterns of leaf structural 

 variation among the four varieties, identifications of coca leaves 

 and leaf fragments are often problematic (and ill-advised) in the 

 absence of relevant ecological and geographic data for the 

 specimens under consideration. The taxonomically most useful 



structural features of cultivated coca leaves are summarized in 

 Table 3. 



COMPARISON OF ARCHEOLOGICAL AND 



RECENT COCA LEAVES 



Although superficially similar in form and venation, leaves of 

 the four modern varieties of cultivated coca can be distinguished 

 on the basis of subtle differences in shape and size, central panel 

 prominence, details of low and high order venation, and 

 stomatal features, especially when such data are integrated with 

 ecological and geographic information for the specimens. On 

 similar grounds, it is possible to determine the specific and 

 varietal affinities of archeological coca leaves. 



Selected leaf structural features of both archeological and 

 recent coca plants from South America are summarized in Table 

 5. These statistical data are of taxonomic value, however, only 

 when assessed together with qualitative aspects of leaf structure. 

 The archeological leaves studied here clearly are more similar to 

 recent leaves of the cultivated cocas than to any wild species of 

 Erythroxylmn (see Tables 3, 4). Although several wild species of 

 Erythroxylum of the neotropical section Archerythroxylum 

 {sensu Schulz, 1907) may resemble cultivated coca varieties in 



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