10 
MERRILL. 
KEY TO THE GENERA. 
J . Petals valvate ; flowers regular ' A. Mimosoideae 
1. Petals imbricate; flowers irregular (nearly or quite regular in Gleditsia, trees 
with branched spines). 
2. Flowers not papilionaceous, the upper petal interior B. Caesalpinioideae 
2. Flowers papilionaceous, the upper petal (standard) exterior. 
C. Papilionatae 
A. Mimosoideae. 
1. Calyx-lobes valvate. 
2. Stamens many, at least more than 10, or more than twice the number of 
petals. 
3. Filaments more or less connate ( Ingeae ) . 
4. Endocarp not distinct from the pericarp and not forming individual 
envelopes about the seeds. 
5. Pods indehiscent, septate between the seeds. 
6. Pod turgid, about 5 cm wide, the sutures not thickened; petals 
adnate below to the staminal tube, otherwise free.— 1. Serianthes 
6. Pod scarcely turgid, spongy or fleshy, less than 2 cm wide, the 
sutures thickened; petals connate below into a tube. 
2. Enterolobium 
5. Pods dehiscent or indehiscent, not septate between the seeds. 
6. Pods very strongly curved or twisted 3. Pithecolobium 
6. Pods straight, not curved or twisted 4. Albizzia 
4. Endocarp distinct and free from the pericarp, the latter not septate, the 
former septate between the seeds and forming an individual envelope 
about each seed ..... . 5. Wallaceodendron 
3. Stamens free; inflorescence capitate {Acacieae) 6. Acacia 
2. Stamens as many as or double the number of petals. 
3. Anthers not gland-tipped. 
4. Pods straight, flat, smooth, with continuous valves, dehiscing through 
the sutures; erect trees — — J S®!. 7. Leucaena 
4. Pods slightly curved or nearly straight, somewhat aculeate, with always 
persistent, indehiscent sutures; suffruteseent herbs or undershrubs. 
5. Pods subcylindric, 4-angled 8. Schrankia 
5. Pods flattened ... 9. Mimosa 
3. Anthers gland- tipped. 
4. Seeds albuminous (Adenanthereae) ; erect trees or shrubs. 
5. Spiny shrubs or small trees ; pods indehiscent 10. Prosopis 
5. Spineless trees; pods dehiscent.. ..L.F a-*-- Vlfell. Adenanthera 
4. Seeds exalbuminous (Piptademeae) ; great climbers, usually tendril- 
bearing, with very large pods and seeds ....... 12. Entada 
1. Calyx-lobes imbricate ( Pcwkieae ) ; very large trees with capitate inflorescence. 
13. Parkia 
B. Caesalpinioideae. 
1. Calyx entire, or the segments above the receptacle more or less united into 
a toothed or lobed tube. 
2. Leaves 2-pinnate; stamens 10 (Dimorphandreae ) . 
3. Erect, unarmed trees, with few, medium to large leaflets; flowers small; 
pods woody, not winged 14. Erythrophloeum 
3. Scandent, usually armed shrubs, with many, usually small leaflets; flowers 
medium-sized; pods thin, winged down one suture {Eucaesalpinioideae) . 
28. Mezoneurum 
