I have examined several hundred trees in the estradas 
which produced the sample analyzed and have found that 
they represent rather typical Hevea Benthamiana. There 
is no Hevea brasiliensis in the Putumayo watershed. 
Hevea guianensis 4ublet var. lutea (Spruce ex 
Benth.) Ducke & Schultes in Caldasia 8 (1945) 249. 
Brazi_: Estado do Amazonas, Rio Negro near mouth of Rio Issana. 
April 7, 1948, Richard Evans Schultes & Francisco Lopez 9784A. 
In the upper Rio Negro basin, very little exploitation 
of Hevea guianensis var. lutea has been carried out be- 
cause of the great abundance of H. Benthamiana which 
is preferred. An analysis of air-dried scrap from the tree 
represented by Schultes & Lopez 9784A gave the follow- 
ing results: ‘‘Resin (acetone extract) 4.97 % ; Rubber hy- 
drocarbon (benzene extract) 86.42%; Insolubles 8.61% ; 
Softer, less strong and tough in comparison to brasilien- 
sis.”” An analysis of the bark from this tree gave the 
following results: ‘Resin (acetone extract) 1.84% ; Rub- 
ber hydrocarbon (benzene extract) 1.25%. Compares 
favorably with crude rubber from some species. ”’ 
Hevea microphylla Ule in Engler Bot. Jahrb. 35 
(1905), t. 1:j, k, 1, m; in Kautschukgewinnung (Kolon- 
ialwirtsch. Kom. 1905) (1905) 10. 
Brazit: Estado do Amazonas, Rio Negro, Sao Felipe, below mouth 
of Rio Issana. ‘“‘Small, whip-shaped tree, basally swollen. Basal 
diameter 9 inches, height 40 feet. Leaflets horizontal to slightly rec- 
linate. Latex sparse, white, thin, not easily coagulating. Bark of ter- 
minal branches red, smooth; of trunk, dark brown-red outside, whitish 
inside, thin, hard, peeling readily. Wood extremely soft, white. 46 
rings.’’ January 8, 1948, Richard Evans Schultes & Francisco Lépez 
9598, 
Ample material of the bark and leaves of this tree was 
taken for chemical analysis. The latex of Hevea micro- 
phylla is, in general, extremely thin and coagulates be- 
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