allied to and coinciding more or less in geographical dis- 
tribution with HZ. Spruceana and AH. similis. 
The problem of the real meaning of Hevea discolor 
was left unattended until 1925, when Ducke (in Arch. 
Jard. Bot. Rio Janeiro 4 (1925) 111) stated that AH. 
discolor Muell.-Arg. and H. similis Hemsley, both from 
the State of Amazonas, have the appearance, the low- 
quality latex and the common name of H. Spruceana, 
and are separated from this species only by a few charac- 
ters of little importance in the leaves and flowers; he 
was convinced that it was a question of mere varieties, 
having found, even among the trees of H. Spruceana at 
Obidos, a strong variation in the size of the flowers. 
Subsequently, in 1929, Ducke (in Rev. Bot. Appl. 9 
(1929) 680) stated that Hevea discolor represents a form, 
not even a geographical variety. Nevertheless, he pointed 
out that in the upper Amazon there is a predominance 
of trees whose leaflets are strongly pilose and which 
correspond especially to discolor; whereas in the lower 
Amazon, the leaves are usually almost glabrous. Ducke 
further noted that sterile specimens of his Hevea Spruce- 
ana forma discolor can easily be confounded with H. 
Benthamiana Muell.-Arg., a fact which he believes is 
the basis of the confusion in the literature of the past, 
which attributed the best rubber of the Rio Negro (ex- 
tracted from H. Benthamiana) to H. discolor. Later, he 
reiterated the same opinion (in Arch. Jard. Bot. Rio 
Janeiro 5 (1930) 156). Five years afterwards, in his mono- 
graph of the genus (in Arch. Instit. Biol. Veg. 2 (1935) 
239), he definitely reduced the binomial Hevea discolor 
to synonymy under H. Spruceana. This treatment is 
retained in Ducke’s most recent synopsis of Hevea (Bol. 
Téen. Instit. Agron. Norte no. 10 (1946) 20, 28). 
Recently, Baldwin (in Journ. Hered. 40 (1949) 48) 
has intimated that the well known and firmly established 
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