with which the bark will peel when small pieces are cut 
from the cambium. The only other species of Hevea 
which I have found to peel so easily is HZ. Spruceana. 
The latex of Hevea microphylla is, in all of the indi- 
viduals examined, extremely sparse and very watery. It 
is almost always white, but occasionally it will darken 
to an ivory color if it stands for several hours. Only one 
tree (Schultes & Lopez 9735) with definitely yellow latex 
was encountered. Coagulation of the latex is always ac- 
complished with extreme difficulty. A specimen pro- 
cured by slow coagulation and drying in the air (without 
the use of acids) remained very sticky for a long period 
of time and was completely devoid of elasticity. Need- 
less to say, Hevea microphylla is never tapped. It is 
important to note this information, since an early and 
widely quoted source (Corréa, Pio M., ‘Flora do Brasil 
(1909) 115) included Hevea microphylla (together with 
HZ. minor and Hi. rigidifolia) in the enumeration of the 
species yielding rubber commercially. Carl D. La Rue 
(‘‘The Hevea rubber tree in the Amazon Valley,”’ 
U.S.D.A. Bull. 1422 (1926) 8), recognizing that Hevea 
microphylla and H. minor represent two distinct con- 
cepts, relegated H. microphylla to those “‘species yield- 
ing poor rubber, rarely collected. ”’ 
The trunk of Hevea microphylla is very characteristic. 
The trees grow in rather dense colonies along the very 
margin of creeks and smaller rivers and on the rim of 
sand islands in the larger rivers. These areas are subject 
to extreme flooding. The usual height of the water dur- 
ing the rainy season, as indicated by waterlines on the 
bark, is ten to twelve feet, but I have encountered areas 
(near Sdio Felipe, for example) where the tree was stand- 
ing in eighteen feet (measured) of water. Inundation 
persists from five to six months, and even during the 
rather pronounced dry season, the ground rarely becomes 
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