BLAKE—AMERICAN SPECIES OF HOMALIUM. 223 
SYSTEMATIC TREATMENT. 
KEY TO SPECIES. 
Flowers sessile or subsessile (pedicels 1 mm. long or less). 
Leaf blades densely griseous-puberulous beneath; styles distinct; stamens shorter 
than the petals............ 22-22 2c eee eee ee eee eee 4. H. puberulum. 
Leaf blades glabrous beneath or merely sparsely pubescent along costa and some- 
times along veins or in their axils; styles united at base into a column, stamens 
equaling or exceeding the petals. 
Calyx segments 0.8 to 1.2 mm. long; petals 1.8 to 2.4 mm. long, 1.3 to 1.8 mm. 
ae C6 : 1. H. densiflorum. 
Calyx segments 1.2 to 2.7 mm. long; petals 2.5 to 3.4 mm. a. long, 1.5 to 2.5 mm. 
wide.’ 
Leaves 6.5 to 13.3 cm. long, incurved-puberulous on costa beneath; ovary 
priseous-Villous ....-.-..-.-. eee ee eee eee eee eee .....2. H. guianense. 
Leaves 14.5 to 17.5 cm. long, spreading-pilose on costa beneath; ovary sparsely 
pilose. ... 22.2... eee eee ee eee eee eee eens 3. H. nicaraguense. 
Flowers distinctly pediceled (pedicels 1 to 7 mm. long). 
Leaf blades more or less densely pilosulous over whole surface beneath. 
Calyx tube rounded at base; stamens in fascicles of 4 to 7, their filaments pilose 
to middle or higher.............-------- eee eee eee eee 5. H. mollicellum. 
Calyx tube contracted into a pediform base; stamens in fascicles of 3, their fila- 
ments glabrou8....-........200---ee eee eee eee eee 12. H. trichocladum. 
Leaf blades glabrous beneath or merely barbellate in the axils of the veins, rarely 
sparsely pubescent along costa and nerves. 
Styles united into a short column at base. 
Ovary glabrous or with a very few long hairs............--. 7. H. leiogynum. 
Ovary densely villous. 
Stamens in fascicles of 4 to 8; calyx segments elliptic-ovate or ovate, 1.5 to 
2mm. wide...........02 2. eee ee eee eee eee eres 6. H. pleiandrum. 
Stamens in fascicles of 3 to 5; calyx segments lanceolate to ovate, 0.7 to 1.8 
mm. wide. 
Younger branchlets glabrous or obscurely puberulous; leaf blades glabrous 
above; petioles glabrous, 2 2 to 7 mm. long....8. H. hemisystylum. 
Younger branchlets griseous-puberulous and sparsely spreading-pilose; 
leaf blades puberulous along midrib above; petioles puberulous and 
pilose, 8 to 12 mm. long...... Lecce eee eee eee 13. H. pedicellatum. 
Styles distinct to base. 
Stamens in fascicles of 5 to 7, pilose to middle........ 17. H. trichostemon. 
Stamens in fascicles of 2 to 4, glabrous or pilose below. 
Calyx segments 4 to 5 mm. long; petals 5.5 to 7 mm. long. 
Calyx segments narrowly lanceolate or subulate-lanceolate, 1 to 1.3 mm. 
wide; leaf blades glabrous above........-.-. 18. H. stenosepalum. 
Calyx segments ovate or elliptic, 1.8 to 2.5 mm. wide; leaf blades densely 
incurved-puberulous along costa above......-. 19. H. eurypetalum. 
Calyx segments 1.5 to 3.6 mm. long; petals 2.5 to 5 mm. long. 
Filaments pilose to middle. Calyx segments 0.6 to 0.7 mm. wide. 
16. H. columbianum. 
Filaments glabrous or sparsely pilose at base. 
Calyx segments 0.5 to 0.8 mm. wide; leaf blades 5.5 to 8.7 cm. wide. 
15. H. hondurense. 
