NEW CONCEPTS IN STYRAX FROM 
EASTERN COLOMBIA 
BY 
Jesus M. [prozo! anp Ricuarp Evans Scour res’ 
THe identification of a number of plants from the iso- 
lated sandstone mountains of the upper Apaporis River 
basin in eastern Colombia has revealed a collection which 
represents a species of Styrax hitherto apparently un- 
described. A distinct form of this species is represented 
by a collection from the ecologically similar sandstone 
mesa at Yapoboda at the headwaters of the Cuduyari, 
in the middle Vaupés River basin. 
In the uppermost reaches of the Apaporis River, where 
the Ajaju and Macaya join, there are a number of gro- 
tesquely eroded quartzite mountains which rise abruptly 
from the flat, extensive Amazonian forest surrounding 
them. They represent the westernmost remnants of an 
ancient, now disrupted, mountain-mass which has its 
center in southern Venezuela and the Guianas. They can 
be followed westward and southwestward throughout the 
Colombian Amazonia where, across the Comisarias del 
Vaupés and Caqueta, there are extensive flat-topped 
ridges, isolated from each other often by many hundreds 
of kilometers. These ridges extend west as far as the 
upper Apaporis basin and San José del Guaviare, and 
southwest to the Falls of Araracuara on the Caqueta 
River (famous as Martius’ westernmost collecting station 
and the type locality of many endemics) and La Chor- 
‘Instituto de Ciéncias Naturales, Bogota. 
? Botanist, Bureau of Plant Industry, Soils and Agricultural Engi- 
neering, U.S. Department of Agriculture; Research Fellow, Botanical 
Museum, Harvard University. 
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