firm, retaining a boggy character. Probably in response 
to this bog or igap6 habitat, Hevea microphylla develops 
a very swollen base. The basal portion of the trunk is 
not actually ‘‘bellied’’ (in spite of the use of the name 
seringueira barriguda—‘‘bellied rubber tree’’—in some 
localities) but is merely swollen. Above the level of the 
high water, the trunk abruptly tapers to a very slender 
and gracefully bent columnar shape (see the schematic 
drawing in the lower left corner of the map). The crown 
is unusually sparse, but the few branches are sufficiently 
heavy to cause a bend in the upper part of the slender 
trunk and, as a result, the whip-shaped habit. In this 
character, Hevea microphylla resembles certain types of 
the igap6-dwelling H. Benthamiana. Although the lat- 
ter is a much stouter and more heavily-crowned tree than 
the former, it also has a very swollen, almost bellied, 
basal portion of the trunk which rapidly tapers upwards. 
[t is almost always possible to ascend with climbing irons 
to the crown of Hevea Benthamiana, which is called 
seringueira chicote or ‘‘whip rubber tree’’ in some locali- 
ties, but the trunk of Hevea microphylla is usually too 
slender and too flexible to support the weight of a man. 
Collection of the foliage and fruit was therefore made 
by felling the tree with an axe from the prow of a canoe 
during the season of deepest inundation. 
In Hevea microphylla, we find a slight variation in the 
position of the leaflets and a very appreciable variation 
in their shape and size. Notes were taken on the many 
trees which were examined. The great majority have 
definitely reclinate leaflets, while a few have them com- 
pletely horizontal to reclinate. Studies have shown that 
the position of the leaflets of an individual tree, once 
they have reached maturity, does not change with age, 
or with seasonal or environmental effects. At the type 
locality, all of the trees which I examined had very 
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