In 1910. Pax treated the species as comprising two varieties: 
var. typica and var. major, on the basis of differences in size of 
the leaflets. 
Unfortunately, Hevea microphylla, which only with the 
greatest difficulty and misunderstanding could be confounded 
with any other species, was, until recently, confused with 
Hemsley’s H. minor, now considered to be a synonym of H. 
pauciflora var. coriacea. In 1906, Huber suggested that Hevea 
microphylla might be synonymous with H. minor, pointing out 
several characters in which the two concepts, as described, 
seemed to agree. He admitted, nonetheless, that there ap- 
peared to be differences in other characters, so he chose ‘‘to 
consider H. microphylla a distinct species for the present’. 
Identifying erroneously a flowering collection of H. micro- 
phylla made by Ducke (Ducke 7027) in the lower-middle Rio 
Negro as H. minor, Huber published an extended description 
of H. minor. In describing the flowers of the Ducke specimens, 
Huber indicated still that the two species appeared to be close 
allies, although he believed that flowers were still unknown for 
H. microphylla. In 1913, he yet maintained H. minor and H. 
microphylla as distinct, including both in his Series /nter- 
mediae as he had done previously — but intimating that 
further studies might make it necessary to remove H. micro- 
phylla and H. minor from Series Intermedia and, together with 
H. rigidifolia, to form a new Series for them. 
Ducke apparently accepted Huber’'s identification of his 
flowering collection (Ducke 7027) as Hevea minor. He had 
collected topotypical material of H. microphylla (Ducke 
HJBR23750) which agreed in all characters with his earlier 
collection (Ducke 7027). Consequently, he reduced H. micro- 
phylla to synonymy under H. minor in 1935, maintaining this 
position in 1946. 
In 1947. Baldwin indicated apparent acceptance of Ducke’s 
treatment of Hevea microphylla. 
In the same year, I studied the type material of Hevea minor 
collected on the upper Rio Negro near the confluence with the 
Casiquiare and herbarium specimens of the Ule and the Ducke 
collections of H. microphylla. It became apparent immediately 
that the two concepts were completely distinct and not in any 
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