In the upper Rio Negro, Baldwin (in Journ. Hered. 38 
(1947) 57) noted the differences between the “*seringa da 
serra’) and the “seringa da caatinga.” pointing out that 
“at Sado Gabriel on the Rio Negro one finds intergrades 
of the two: the former he called FZecea pauciflora, the 
latter AZ. confusa, thus intimating that the greater part of 
the British Geuiana maternal and the “seringa da caatin- 
ga of the Rio Negro belong to the same concept. He 
has continued to hold this opinion in’ later publications 
(Baldwin and Schultes in) Bot. Mus. Tent. Harvard 
Univ. 12 (1947) 835). 
After having spent a vearin the upper Rio Negro val- 
ley and having studied material in American and Euro- 
pean herbaria, Tamof the opinion that: (1) the British 
Cruiana material which Plemsley called FZeceda confiusa 
is, With some variability. the same concept as the “serra 
da caatinga” of the upper Rio Negro: that (2) these are 
varietally distinct from typical #fevea pauciflora known 
principally from: rocky situations along the uppermost 
reaches of the Rios Negro and Orinoco: and that (3) 
they represent the same concept deseribed by Ducke as 
Hevea pauciflora var. corrvacec. While a full) biological 
study of the FLevea pauciflora complex should await still 
further field) studies, an examination of the availible 
herbarium material brings into evidence the thet that 
differences do exist. Nevertheless, | have not found sut- 
ficient differences in floral or fruiting structures to war- 
rant a specific rank. In 1948 (in Bot. Mus. Leatl Har- 
vard Univ. 13 (1948) 117). T argued for the maintenance 
of a varietal rank pending further field studies. Ducke 
(in Bol. Teen. Inst. Agron. Norte no. 10 (1946) 18, 23) 
likewise has indicated his belief that the British Guiana 
material should be maintamed asa variety, stating, how- 
ever, that he was in doubt as to whether FZecvea confusa 
should be kept up as a distinet variety of FLecea panuci- 
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