科研之友
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摘要
with the aim of pointing out useful character for taxonomic purposes, westudied the leaf of the erythroxylum species that grow on cerrado vegetation in sˋo paulo state, brazil (e. ambiguum, e. campestre, e. cuneifolium, e. deciduum, e. microphyllum, e. nanum, e. pelleterianum, e. suberosum and e. tortuosum). they are all covered by granules or platelets of epicuticular waxes of sparse or dense distribution. the venation is of camptodromous - brochidodromous pattern, the mesophyll is dorsiventral and the stomata occur only on the abaxial surface. some features, such as acuminated margin, midrib region with adaxial projection, lateral vascular bundle surrounded by a parenchymatous sheath and petiole with vascular tissue in an opened arc-shape, are widely distributed amongst the studied species. others, like rounded margin, midrib with only one vascular bundle, papillose epidermis on the abaxial surface, and occasionally bi-layered on the adaxial surface, besides scattered sclereids on the mesophyll, occur only in some taxa. the occurrence or not of these leaf features allowed the elaboration of an identification key for the erythroxylum species.
