BULLETIN 1422, XT. S. DEPARTMENT OE AGRICULTURE 
Pax (31) , in Engler's Pflanzenreich, recognized the following species : 
H 
Hevea benthamiana Muell. Arg. 
H. discolor Spruce. 
H. duckei Huber. 
H. nitida Muell. Arg. 
H. paludosa Ule. 
H. brasiliensis (H. B. K.) Muell. 
var. janeirensis (Muell. Arg.) Pax. 
H. janeirensis Muell. Arg. 
H. sieberi Warburg. 
Siphonia brasiliensis H. B. K. 
var. stylosa Huber. 
var. cuneata (Huber) Pax. 
H . lutea var. cuneata Huber. 
H. cuneata Huber. 
H. sp. lt itauba" Ule. 
H. peruviana Lechler ex Huber. 
var. randiana (Huber) Pax. 
H. lutea (Benth.) Muell. Arg. 
H. apiculata Baill. 
H, lutea var. apiculata Muell. Arg. 
H. peruviana Lechler ex Benth. 
Siphonia lutea Benth. 
Siphonia apiculata Spruce ex Baill. 
H. rigidifolia (Benth.) Muell. Arg. 
Siphonia rigidifolia Spruce. 
H. spruceana (Benth.) Muell. Arg. 
Siphonia spruceana Benth. 
Pax pointed out the great difficulty encountered in delimiting 
species of Hevea with such material as is available, which in the case 
of only a few species consists of specimens of leaves, flowers, and 
fruits and even in some of these offers no certainty that the different 
structures are derived from the same source. Pax decried the practice 
(to which he feels Huber was especially addicted) of describing species 
from leaf specimens only. 
Huber (9, 11) recognized 24 species in the genus, which are listed 
below: 
H. similis Hemsl. 
H. discolor (Benth.) Muell. Arg. 
H. paraensis Baill. 
Siphonia discolor Benth. 
Micrandra ternata R. Brown. 
H. minor. 
H. microphylla. 
var. typica Pax. 
var. major Pax. 
H. pauciflora (Benth.) Muell. Arg. 
H. confusa Hemsl. 
H. spruceana Oliv. 
Siphonia pauciflora Benth. 
membranacea Muell. Arg. 
H. spruceana Oliv. 
H. guianensis Aubl. 
Jatropha elastica L. 
Caoutschoua elastica Gmel. 
Siphonia cahuchu Willd. 
Siphonia elastica Pers. 
Siphonia guianensis Juss. 
Siphonanthus elasticus Schreb. 
H. nigra Ule. 
H . collina Huber. 
Hevea guianensis Aubl. 
H. spruceana Muell. Arg. 
H. nigra Ule. 
var. tridentata Hub. 
H. apiculata Baill. 
H. similis Hemsley. 
H. cuneata Hub. 
H. discolor Muell. Arg. 
H. peruviana Lechler. 
H. confusa Hemsley. 
H. benthamiana Muell. Arg. 
H. pauciflora Muell. Arg. 
H. duckei Hub. 
H. nitida Muell. Arg. 
H. paludosa Ule. 
H. viridis Huber. 
H. rigidifolia Muell. Arg. 
H. kunthiana (Baill.) Huber 
H. minor Hemsley. 
H. foxii Huber. 
H. microphylla Ule. 
H. glabrescens Huber. 
H. randiana Hub. 
H. lutea Muell. Arg. 
H. brasiliensis Muell. Arg. 
var. stylosa Hub. 
From an examination of the type material in the Museu Goeldi of 
a number of Huber's species, the writer is inclined to believe that 
Huber, although in all probability better acquainted with the genus 
Hevea than any other botanist, was too much inclined to describe 
species from inadequate material and to base them on rather small 
and not certainly constant differences. 
A satisfactory revision of the genus can not be made until more 
extensive collections than are now available have been assembled. 
Flowers, or fruit, or both are lacking in too many type specimens. 
