1	Foliar gland absent		(2)
+	Gland present on the leaf rachis		(3)
2 (1)	Three stamens at least twice as long as the other, with deeply (twice) curved filaments, which are many times as long as the anthers. Anthers finally longitudinally split, not distinctly basifixed. Transverse septa of the pod entire (subgenus Cassia)		(4)
+	All stamens nearly equally short, often two or three slightly longer, filaments shorter than or as long as their anthers. Anthers opening by single or double terminal pores, basifixed. Transverse septa of the fruits entire or not (subgenus Senna)		(8)
3 (1)	Sepals blunt or rounded. Leaflets in few or many pairs, vary rarely narrow. Fruits indehiscent or sub-dehiscent. Seeds transverse or longitudinal. Bracteoles present or absent. Funicle Capillary subgenus Senna)		(14)
+	Sepals vary acute. Leaflets in many pairs, very narrow, rarely few pairs and broader. pods flat, dehiscent. Seeds ongitudinal. Bracteoles present. Funicle short, broad, + triangular (sub-genus Lasiorhegma)		(24)
4 (2)	Petals yellow to golden; bracts vary small, falling off long before flowers appear		Cassia fistula
+	Petals pink or red, fading to buff, orange or white; bracts persisting till flowers open		(5)
5 (4)	Ovary glabrous; leaflets oblong		Cassia renigera
+	Ovary pubescent; leaflets variable		(6)
6 (5)	Petals up to 1.5 cm long; filaments not swollen in the middle		Cassia roxburghii
+	Petals (1.5) 2-3.5 cm long; filaments markedly swollen in the middle		(7)
7 (6)	Stipules c.5 mm long, narrow, not leafy, leaflets usually acute		Cassia nodosa
+	Stipules c. 12-15 mm long, leafy, leaflets usually obtuse		Cassia javanica
8 (2)	Leaflets 5 cm or more long		Cassia alata
+	Leaflets less than 5 cm long		(9)
9 (8)	Stipules c. 1-2.5 cm long, c. 5 mm broad, acuminate		Cassia didymobotrya
+	Stipules c. 7 mm or less long		(10)
10 (9)	Leaflets acute		Cassia senna
+	Leaflets obtuse		(11)
11 (10)	Tree, inflorescence panicle of corymbs		Cassia siamea
+	Herb or undershrub, inflorescence a raceme. a raceme		(12)
12 (11)	Pod without ridges on the valves		Cassia holosericea
+	Pod with ridges on the valves		(13)
13 (12)	Petiole c. 1-3.5 cm long, raceme 6-23 cm long, longer or equal to subtending leaves. Sepals 8-13 mm long. Petals 9-20 mm long		Cassia italica ssp. italica
+	Petiole c. 1-2.5 cm long, raceme 2-8 cm long, smaller than subtending leaves. Sepals 5-8 mm long. Petals 8-9 mm long		Cassia italica ssp. micrantha
14 (3)	Gland inserted on the petiole above, not between the leaflets		(15)
+	Gland inserted between first or more pairs of leaflets		(17)
15 (14)	Bracts acute, more than 5 mm long .Peduncle 0.3-0.8 mm long carrying 2-4 flowers. Foliar gland Ovoid, short, squat		Cassia occidentalis
+	Bracts blunt, 4-5 mm long. Peduncle c. 1-2.8 cm long, carrying 4-10 flowers. Foliar gland narrow, Subulate-clavate		(16)
16 (15)	Leaf 14-21 cm long, leaflets 4-12 pairs. Pod 9-10 cm long		Cassia sophera
+	Leaf up to 9 cm long, leaflets 3-5 pairs. Pod 5-7.5 cm long		Cassia purpurea
17 (14)	Stipules c. 5 mm or more broad		(18)
+	Stipules less than 5 mm broad		(19)
18 (17)	Glands absent or reduced and irregularly placed		Cassia didymobotrya
+	Glands well developed, present between the leaflets		Cassia auriculata
19 (17)	Leaflets obovate		(20)
+	Leaflets not obovate		(22)
20 (19)	Ten perfect stamens present		Cassia surattensis var. suffruticosa
+	Seven perfect stamens present, three staminodial or absent		(21)
21 (20)	Gland between the lowest pair of leaflets, pedicel 1.2-3.5 cm long (rarely as short as 5 mm), 1.5-4.5 cm in pods, areoles on both sides of the seed, narrow linear, .3-.5 mm wide		Cassia obtusifolia
+	Gland between two lower pairs of leaflets, Pedicel (of flower) c. 4-10 mm long , (of pods) up to 15 mm; areoles on both sides of the seed, 1.5-2 mm wide, often almost as wide as the seed		Cassia tora
22 (19)	Leaves with 2-3 pairs of leaflets		Cassia corymbosa
+	Leaves with more than 3 pairs of leaflets		(23)
23 (22)	Three upper stamens staminodial		Cassia floribunda
+	Ten perfect stamens present		Cassia surattensis var. surattensis
24 (3)	Leaflets 2 (or 1) pairs, plants viscid, hairy, stamens 5, no staminodes		Cassia absus
+	Leaflets more than 5 pairs, plants not viscid, stamens usually 10 (rarely 9,7 or 5)		(25)
25 (24)	Foliar glands distinctly stiped		Cassia pumila
+	Foliar glands sessile		(26)
26 (25)	Stamens 4-5 (subequal)		Cassia hochstetteri
+	Stamens 10, sometimes 7		Cassia wallichiana