510 
ROBINSON. 
many individuals have been collected have only one kind, but it is probable 
that every species may be both monoecious and dioecious. In one case, 
both kinds of flowers were found in one receptacle, but this was not even 
true of other receptacles on the same plant: a few species are known with 
both kinds of receptacles at the same node, in the only case of this seen 
in Philippine plants, the next nodes had one kind only. The terminal 
acumen is regularly used and although it is often possible to find on the 
same plant some leaves where it is well developed and others whose, apices, 
are nearly obtuse, it is often useful. The serrations In a great majority 
of species vary on the same leaf, the lower being very acute, the upper 
various : yet they are very useful in separating species by the eye : the 
stipules are very useful, but are deciduous in many species ; the cystoliths 
are often but not always very characteristic. The following key, intended 
partly as an aid to field-study and partly to indicate the real differences 
between the species, has been framed in part on somewhat artificial 
characters : these have not been used except when they seemed to separate 
species otherwise distinct. In citing affinities, the difficulty is to de- 
termine from description which characters are of greater importance. 
KEY TO THE PHILIPPINE SPECIES OP ELATOSTEMA. 
1. Staminate receptacles borne on slender peduncles, unknown in E. obovatum and 
E. variabile, at least their outer bracts corniculate, or in E. glaucescens and 
E. clelicatulum distinctly acuminate, in E. carinoi not corniculate. 
2. Plants erect or creeping only at base; leaves medium-sized, only smaller 
leaves of a plant or leaves of reduced plants as short as 4 cm, usually 7 
to 10 cm long, or even more. 
3. Staminate bracts corniculate. 
4. Stems entirely glabrous. 
5. Leaves ovate to obovate .IBB.:..— 1. E. luzonense 
5. Leaves narrowly oblong or oblong-lanceolate 2. E. variabile 
4. Stems pubescent. 
5. Apical leaf-tooth lanceolate or ovate, forming a distinct acumen, basal 
auricle short, not overlapping stem. •.... 9. E. simulans 
5. Apical tooth triangular or much wider than long, hardly or not ex- 
tending beyond general leaf -outline ; basal auricle wide, overlapping 
stem 10. E. obovatum 
3. Staminate bracts not corniculate iLh..... 28. E. carinoi 
2. Creeping plants. 
3. Leaves medium-sized, 7 to 11 cm long 3. E. longipechunculatum 
3. Leaves small, only occasionally as much as 4.5 cm long, never caudate- 
acuminate. 
4. Stems retrorsely spinulose or tuberculate; venation pinnate. 
4. E. pinnatinervium 
4. Stems glabrous or obscurely retrorsely pilose; leaves triplinerved. 
5. Leaves oblanceolate to pbovate .‘....i.SsB 5. E. filioaule 
5. Leaves lanceolate to ovate ; ~ 6. E. inaequifolium 
4. Stems antrorsely pilose or setose; leaves triplinerved, except partly in 
E. heterophyllum and E. cheirophyllum. 
