THE VARIABILITY OF HEVEA MICROPHYLLA 
From an evolutionary point of view, Hevea micro- 
phylla is one of the most fascinating species of the genus. 
It is morphologically very distinct from all other species 
in the form and dehiscence mechanism of its fruit. As 
has been pointed out (Schultes loc. cit.), the capsule of 
Hevea microphylla, the valves of which never become 
woody but remain thin and coriaceous, opens slowly, 
not explosively, drops the seed directly beneath the tree, 
and remains attached for some time to the peduncle. 
Furthermore, this species is the only one in which the 
fruit normally ripens yellow. The epicarp, which is ex- 
ceptionally thin and at first a deep, dark green, gradu- 
ally lightens, becomes yellower, until the completely 
mature fruit is often a canary-yellow, with six green 
stripes along the three parietal sutures and the three 
dorsal keels of the carpels. The basal portion of the very 
ripe capsule has a definite cherry-red hue near the pe- 
duncle and this color, often spreading rather widely, ap- 
proaches the sides of the capsule. One collection (Schultes 
& Lopez 9812) had fruits which were reddening at the 
base, near the peduncle. It would seem that this red 
color is correlated with some chemical alteration which 
takes place the last few days before complete ripening 
(i.e., during the final ‘‘drying out’’ of the fruit structure 
which leads to dehiscence). I believe this because the red 
appears at the tip rather suddenly and spreads speedily 
just before dehiscence. This rapidity is more noticeable 
in Hevea microphylla than in any other species with the 
curious red hue. This bright red color is also particularly 
noticeable in the ripened capsules of Hevea nitida; 
whereas in HZ. pauciflora and H. rigidifolia, a very defi- 
nite dull purplish-red is characteristic. In all other spe- 
cies of the genus, the mature capsule is normally green, 
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