Colombia other than “‘siringa’’ or ‘‘siringa blanea.’’ It 
yields a product only slightly inferior to that of Hevea 
brasiliensis. 
Hevea Benthamiana is represented in various parts of 
eastern Colombia by a number of rather distinct varieties 
and forms which are not yet sufficiently well understood 
to be described. I believe that more exploration and 
study will show that this is the most variable species in 
Colombia. 
Hevea brasiliensis (HBK.) Muell.-Arg. var. 
subconcolor Ducke in Arch. Jard. Bot. Rio Janeiro 
6 (1988) 55. 
Hevea nitida Mueller-Argentius in Martius F]. Bras. 
11 (1874) 301. 
Hevea brasiliensis, a widespread species in the Amazon 
Valley, occurs in Colombia apparently only in the south- 
ern half of the ‘‘trapecio amazonico’’—in the Leticia 
area—where it is represented by the very strikingly dis- 
tinct variety swbconcolor. This variety, with firmly char- 
taceous or thinly coriaceous leaflets which are nearly as 
green beneath as above and very glossy on both surfaces, 
was described from the nearby Brazilian locality of Sao 
Paulo de Olivenga. In Colombia, it is a tree of heavily 
floodable areas and occurs along river and creek banks, 
but not to any appreciable extent on land which is above 
the height of the annual floodwaters. In Leticia, it is 
referred to as ‘‘siringa fina.’’ It yields the highest grade 
of Colombian Hevea rubber, the so-called ‘‘ Up-River’’ 
or “‘Alto-Rio’’ grade. 
The specific concept described by Mueller in 1874 un- 
der the name Hevea nitida is known only from the type 
material which von Martius collected ‘‘in prov. do Alto 
Amazonas, in silvis secus flumina Solimoés et Amazon- 
ium.”’ In his ‘* Revision of the Genus Hevea, mainly the 
ae 
