BOTANICAL MUSEUM LEAFLETS 
HARVARD UNIVERSITY 
A NEW INFRAGENERIC CLASSIFICATION 
OF HEVEA 
RICHARD EVANS SCHULTES 
I. HISTORICAL CONSIDERATIONS ON 
INFRAGENERIC CLASSIFICATIONS 
The genus Hevea, now the source of 98% of the world’s 
natural rubber, was first known to botany in 1775, when Aublet 
accurately and thoroughly described Hevea guianensis from 
French Guiana. For half a century, this was the only species 
known to science. 
In 1824, Willdenow recognized a rubber-yielding tree col- 
lected near the mouth of the Amazon as a distinct species and, 
without actually describing it, he named it Siphonia brasilien- 
sis. A year later, Humboldt, Bonpland and Kunth described as 
Siphonia brasiliensis a plant from the Orinoco, where what we 
know as Hevea brasiliensis does not occur. Since Willdenow’s 
species is what we now recognize as true H. brasiliensis and 
since, in lieu of a description, he published diagnostic drawings 
of the critical parts of the plant, his “description” of H. 
brasiliensis is accepted on the basis of priority. 
The genus Siphonia was later shown to be congeneric with 
Hevea. Siphonia brasiliensis was transferred by Mueller Ar- 
goviensis in 1865 to H. brasiliensis. 
In 1854, five new species were described (under Siphonia) by 
Bentham, and the following year another was proposed by 
Spruce — all on the basis of the extensive collections sent from 
Brazil by the English plant explorer, Richard Spruce. 
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