* Hevea rigidifolia (Benth.) Mueller-Argentius in 
Linnaea 34 (1865) 208. 
Hevea rigidlfolia, collected by Spruce in catinga for- 
ests along the Rio Vaupés at Panuré in Brazil (near the 
Colombian boundary), is known only from the type ma- 
terial. It seems entirely probable that this species will 
be found in Colombia. I have examined a duplicate type 
which is preserved in the Gray Herbarium and find that 
it is an extraordinarily distinct species which resembles 
no other known representative of the genus. The leaflets 
are glabrous, glossy, rigidly thick-coriaceous with strong, 
recurvate margins. 
Hevea viridis Huber in Rev. Cult. Colon. 10 (1902) 
194. 
Hevea viridis occurs in two very different habitats, but 
always in the vicinity of sandstone or granitic rock out- 
crops. In the igapés subjected to heavy inundation each 
year, it becomes a very robust tree; on rocky hillsides 
and sterile places near falls and rapids, it is a medium 
sized and poorly developed tree, superficially resembling 
Hevea pauciflora var. coriacea. Its chief characters, how- 
ever, are exceedingly constant despite the wide variance 
in its chosen habitats. I have never encountered Hevea 
viridis in the areas of inundation where rock outcrops are 
remote. The latex of this species is yellowish (in igapés) 
or, rarely, white (in drier, rockier locations) and gives a 
sticky rubber devoid of elasticity. It not only yields a 
product which is of no commercial value, but it will spoil 
the latexes of other species if mixed with them. In the 
Vaupés, the common name is ‘“‘siringa pegajosa. ”’ 
Hevea viridis Huber var. toxicodendroides 
R.E. Schultes & HE. LL. Vinton in Caldasia 8 (1944) 25. 
Hevea viridis var. toxicodendroides is a bushy or shrub- 
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