technical literature. Some include Micrandra in lists of rubber- 
yielding species. While this is strictly correct, the unfortunate 
impression is often given that Micrandra should be counted 
amongst the commercial sources or rubber (Clouth, F.: “Rubber, 
gutta-percha and balata” (1903) 30; Walle, P.: “Au pays de l’or 
noir, le caoutchouc de Bresil,” ed. 2 (1912) 124; Carneiro, A. J. 
de Souza: “Rubber in Brazil” (1913) 8; Ferguson, Jr. ed. 3: “All 
about rubber and gutta-percha” (1899) iii, clxxxiv). This last 
source states that it grows along the most “steamy valleys” of the 
Amazon and is indiscriminately cut by the natives “to furnish 
Para rubber”! Others definitely assert that Micrandra-rubber 
was actively exploited and entered into commerce either alone 
or as an adulterant of Hevea-rubber (Morris, D.: “Plantes pro- 
duisant le caoutchouc du commerce” in Bull. Soc. Etudes Colon. 
no. 5 (1899) 178; Ehrhardt, K.: “Die geographisch Verbreitung 
der fiir die Industrie wichtigen Kautschuk- und Guttaperchap- 
flanzen” (1903) 26; Seeligmann, T., G. Lamy-Torrilhon & H. 
Falconnet: “Indian rubber and gutta-percha,” ed. 2 (1910) 15; 
Ramondt, A. S.: “Caoutchouc, guttah-pertja en balata (1907) 6). 
Still others quite correctly assert that rubber from Micrandra is 
said to enter the trade, passing as a grade of Para rubber 
(Hevea), but that no precise information on this point can be 
cited to substantiate the report (Warburg, O.: “Les plantes a 
caoutchouc et leur culture” (1902) 21, 48; Jumelle H.: 
“Les plantes a caoutchouc et a gutta” (1903) 60; Reintgen, P.: 
“Die Geographie der Kautschukpflanzen” (1905) 25; Schidro- 
witz, P.: “Rubber” (1911) 33; ed. 2 (1916) 33; Brown, H.: 
“Rubber, its sources, cultivation and preparation” (1914) 33). 
Occasionally, a report will credit Micrandra with producing in 
the Hevea-rubber districts of the Amazon the most highly 
esteemed grade of rubber (Pontio, M.: “Analysis du caoutchouc 
et de la gutta-percha” (no date) 8). 
During my twelve-year study of lacticiferous plants in the 
Amazon Valley—especially in northwestern Brazil and south- 
eastern Colombia—I saw no evidence of exploitation of Micran- 
dra trees for their rubber. This was true even in areas where 
Micrandra was extremely abundant and easily accessible. Furth- 
ermore, I saw no evidence, such as scars on the bark, that such 
exploitation had been carried on in the past, although former 
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