mais estreitas que em qualquer especimen de Bentham- 
lana, por mim visto.”’ 
The extensive Froes material, with its abundance of 
flowers, enables us to evaluate more critically and more 
extensively than has hitherto been possible the relation- 
ships of Hevea rigidifolia. It would appear quite prob- 
able that Hevea rigidifolia occupies a somewhat inter- 
mediate position between Hevea pauciflora var. coriacea” 
and HI. Benthamiana,” having, florally at least, closer 
affinities with the latter than with the former. 
The extremely heavy coriaceous nature and the glau- 
cescence of the leaflets of Hevea rigidifolia as well as the 
glabrous condition of the lower surface of the leaflets 
In the present article, I am using the concept Hevea pauciflora 
var. coriacea in the sense in which it has been established and used 
by Ducke (in Arch. Instit. Biol. Veg. Rio Janeiro 2, no. 2 (1935) 
239). The concept has also been used in this sense in several of my 
previous papers (in Bot. Mus. Leafl. Harvard Univ. 12 (1945) 1-32; 
in Rev. Acad. Colomb. Ciéne. Exact. Fisico-Quim. Nat. 6, no. 22-23 
(1945) 331-888; in Rev. Fac. Nac. Agron. (Medellin) 6, no. 22 
(1946) 18-45). I suspect that what has been considered as Hevea 
paucifilora var. coriacea represents a concept deserving varietal distine- 
tion. Baldwin calls this H. confusa (Baldwin: in Journ. Hered. 38 
(1947) 54; Baldwin & Schultes in Bot. Mus. Leafl. Harvard Univ. 
12 (1947) 335). Until it is possible to investigate the entire Hevea 
pauciflora complex critically, however, I believe it is advisable to main- 
tain Ducke’s treatment of it. A complete study of the H. paucjflora 
var. coriacea— H. rigidifolia—H. nitida—H. confusa problem and of the 
relationships between these concepts is urgently needed and must be 
carried out before a clear understanding of the genus as a whole can 
be expected. Ducke has recently (in Bol. Téen. Instit. Agron. Norte 
no. 10) (1946) 18) indicated doubt as to whether Hevea confusa should 
be maintained as a variety of H. pauciflora or incorporated with H. 
paucifiora var. coriacea. 
The writer believes that Hevea Benthamiana and H. Spruceana 
(Benth.) Muell.-Arg. are distantly allied species and that some rela- 
tionship could, therefore, be expected to exist between H. rigidjfolia 
and H. Spruceana. Since it appears, however, to be of a minor degree, 
a detailed analysis of this relationship will not be discussed in the 
present study. 
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