should indicate otherwise, there seem to be no varieties 
or forms of the concept, a condition which does not ap- 
pear to exist in any other well-known species with the 
possible exception of H. microphylla, All of the collec- 
tions indicate that Hevea rigidifolia is a small tree, usu- 
ally between twenty and thirty feet in height. However, 
there is apparently considerable variation in the diameter 
of the trunk which may measure, according to Fré6es, 
from eight to twenty-five centimeters; this variability in 
the size of the trunk is found in a large number of small 
trees which grow under the xerophytic conditions of 
‘aatingas,. 
The leaflets of Hevea rigidifolia are apparently always 
of the same consistency, color and glaucescence; their 
adult size is very constant, varying usually from 10 to 18 
em. in length and 4.5 to 6.5 em. in width; they are al- 
rays peculiarly and strongly recurved-marginate ; their 
tips are consistently long and sharply cuspidate-acumi- 
nate; there is never any trace of pilosity in the axils of 
the nerves; the number of secondary nerves is twelve to 
fifteen. Occasionally (as in F’rdes 21394) the strongly 
rounded base of the leaflets departs from the cuneate 
condition which is usual in this species; this is, curiously 
enough, the only vegetative variation of importance 
which was noted, except for a very slight divergence 
from a perfectly oblongate-elliptic shape (as in some 
specimens of Frdes 21253). 
The inflorescences in all of the collections are peculiarly 
rigid, are profusely flowered, and are more or less equal 
or subequal to the leaves. 
No variations of any sort in the form of the staminate 
buds is apparent; all are very strongly cylindric-conic, 
conspicuously acuminate, and densely clothed with a 
white indumentum. The pistillate flowers, with the 
spreading and sharply recurved narrow acuminate tips 
[112 ] 
