Iquitos, Perti, is what I consider to be a hybrid swarm 
of Hevea confusaX H. guianensis... . From that popu- 
lation at Iquitos, Ule described H. paludosa, and Ducke 
named HZ. humilior. The plants are doubtless extracts 
from a hybrid swarm, with strong resemblance to HZ. 
confusa.”’ 
In his study of the genus Hevea in Pert, Seibert (1.c. 
302) discussed H. humilior in detail: ‘“The type material, 
in both species LA. humilor and H. paludosa] is thought 
to represent segregating material from an hybrid swarm 
derived through interspecific hybridization of HI. pauci- 
flora and H. guianensis var. lutea. In both Hi. paludosa 
and H. humilior the material most closely simulates Hi. 
paucifiora, and recent collections have been labeled AH. 
pauciflora var. coriacea by Ducke. The presence of A. 
guianensis var. lutea is morphologically more difficult to 
distinguish in the types of HZ. humilor than in A. palu- 
dosa; but, at least through bud acumination and pubes- 
cence characters, there can be little doubt of its presence. 
“Tf H. paucifiora and H. guianensis var. lutea were 
the only species concerned in producing the Iquitos hy- 
brid swarm the problem would be relatively simple. The 
swarm is complicated in that segregates of HZ. pauciflora 
X< brasiliensis also appear. Morphological evidence from 
the leaves, short-shoots, bud acumination and contortion, 
calyx-lobe acumination, and seed characters can leave 
little doubt of such a condition existing. 
‘*. . The Iquitos hybrid swarm complex is still insuf- 
ficiently known and collected to give more than faint, in- 
conclusive evidence that certain specimens show influence 
of all three species within the same plant.’’ In further- 
ance of his study of these Iquitos trees, Seibert appends 
(1.c. 817) a scholarly and original analysis of the material 
available. 
Hybridization is probably of relatively common occur- 
[ 271 | 
