stable, showing variations which are surprisingly slight 
for the genus. On the basis of a study of this new ma- 
terial, we can now attempt to discuss the relationships 
of Hevea rigidifola with other species. Furthermore, 
the examination of the Froes material has convinced me 
more firmly than ever that it is imperative to bring this 
species, which has a number of unusual characteristics 
found in no other species, into cultivation on a large 
scale for investigations in selection and hybridization and 
to study even more intensively its relationships. 
There have been four descriptions of Hevea rigidifolia, 
including the original, but they have all been based on 
the type collection. The original description is very short 
and has proved to be inadequate, in view of the compli- 
cations which are presenting themselves in the detailed 
and critical studies of the genus as to its subspecific con- 
cepts and phylogenetical relationships. The second’ and 
third’ descriptions, those of Mueller-Argoviensis, are 
Be* | |... foliolis coriaceis margine recurvis, alabastris masc. cylin- 
drico-conicis angustis, calycibus pro 2/3 longitudinis partitis, laciniis 
triangulari-lanceolatis acute acuminatis, disci masc. glandulis lanceo- 
lato-subulatis glabris, antheris 6-10 irregulariter biseriatim verticilla- 
tis, columna supra-staminali integra glabra, stigmatibus breviuscule 
stipitatis... Arbor 30-pedalis. Foliola circ. 9-12 cm. longa, 4-5 cm. 
lata, lanceolato-elliptica, acute acuminata, basi acuta, subtus sub- 
glaucescentia, supra—laevigata, glabra, multo crassiora quam in con- 
generibus. Costae primariae crassae, secundariae tenuiores, subtus 
prominentes ; venae validiusculae, subdeplanatae. Paniculae amplae, 
albido-v. cinereo-tomentellae. Calyces masc. aperientes 4 mm, ae- 
quantes v. paulo longiores, foeminei aperti usque 7 mm. longi, intus 
circa fundum minute subulato-glanduligeri; laciniae longe et anguste 
acuminatae. ”’ 
#** |. . foliolis coriaceis margine recurvis; alabastris masc. cylin- 
drico-conicis angustis; calycibus pro 2/3 v. 3/5 longitudinis partitis, 
laciniis e base triangulari anguste lanceolatis acute acuminatis; disci 
masc. glandulis lanceolato-subulatis glabris; antheris 6-10 irregulari- 
ter biverticillatis, columna suprastaminali angusta glabra; stylo brevi 
distincto, ovario glabro. 
**ArBor 30-pedalis. Perrott validi, foliola aequantes v. iis longiores, 
[ 99 | 
