1	Trees; leaflet blades 8-16 mm wide; flowers 7-10 cm, falcately curved in bud; legume 7-8 mm wide.		4 S. grandiflora
+	Herbs, annual or perennial and suffrutescent; leaflet blades 2-4(-7) mm wide; flowers usually less than 2 cm, not or only slightly falcately curved in bud; legume 2.5-4 mm wide		(2)
2 (1)	Leaves 20-40-foliolate; leaf rachis 4-10 cm, internodes often less than 3 cm, node often gibbous; corolla standard 1.1-1.3 cm.		3 S. sesban
+	Leaves 40-80-foliolate; leaf rachis 13-30 cm, internodes often more than 3 cm, node not gibbous; corolla standard 0.9-1 cm		(3)
3 (2)	Branchlets, leaf rachises, and flower rachises without prickles; leaflet blades adaxially ± villous when young, glabrescent; standard wider than long.		1 S. cannabina
+	Branchlets, leaf rachises, and flower rachises with ± projected prickles; leaflet blades usually glabrous; standard longer than wide.		2 S. bispinosa