he did not, at that time, clearly delimit the former from 
the latter species. He wrote (loc. cit. 682), translated: 
‘*Pertaining undoubtedly to the Luteae series because of 
the disposition of the anthers, Hevea rigidifolia occupies, 
from other points of view, a special position in this group 
.... In its whitish pubescence and acuminate staminate 
buds, the inflorescence strongly suggests Hevea brasilien- 
sis GHBK.) Muell.-Arg. Furthermore, the segments of 
the disk of the staminate flower are more strongly de- 
veloped in this species [i.e. HZ. rigidifolia) than in any 
other species.”’ Later, the same investigator (in Bol. 
Mus. Paraense 7 (1918) 202) indicated that the position 
of Hevea rigidifolia in the Luteae series was open to some 
doubt; and (loc. cit. 206) that it might be necessary to 
remove Hi. microphylla Ule™ and H. minor from series 
Intermediae (he considered series Luteae and Intermediae 
to represent provisional classifications and not natural 
groups) and, together with Hi. rigidifolia, form a new 
group which would be characterized by a strong develop- 
ment of the segments of the staminate disk. 
Ducke more recently stated (in Arch. Instit. Biol. 
Veg. Rio Janeiro 2, no. 2 (1985) 285): ‘‘According to 
the descriptions, the specie [1.e.: Hevea rigidifolia] dit- 
fers from H. Benthamiana principally by its glabrous 
rigid coriaceous leaflets with recurvate margin; the dis- 
cus and the anthers (6 to 10) do not seem to differ in any 
essential character from those of the typical Bentham- 
zana.’’ After having had occasion to see the Frées ma- 
terial, Ducke (in Bol. Téen. Instit. Agron. Norte no. 10 
(1946) 13) wrote in regard to Hevea rigidifolia ‘‘distingue- 
se, de uma Benthamiana de folhas inteiramente glabras, 
pela consistencia rigidamente coriacea das mesmas. .. . 
as flores masculinas sio mais longamente acuminadas e 
' Until recently confused with Hevea minor. 
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