1	"Pod cylindrical, containing pith; leaves always glandular"	2
1	"Pod flat or compressed or, if cylindrical, then the leaf rachis eglandular"	12
2	"Gland(s) located at or near the base of petiole"	3
2	"Glands located between pairs of leaflets"	7
3	"Pod more than 10 cm long; seeds 40–100 per pod"	4
3	"Pod less than 10 cm long; seeds 20–40 per pod"	5
4	"Petiole 20–40 mm long; peduncle 2–5 mm long; leaves initially pubescent, soon glabrescent"	"Senna occidentalis"
4	"Petiole 40–65 mm long; peduncle c. 10 mm long; leaves persistently pubescent"	"Senna hirsuta"
5	"Gland on the petiole erect, taller than broad"	"Senna clavigera"
5	"Gland on the petiole broader than tall"	6
6	"Petiole 10–20 mm long; leaflets 4–9 mm wide; anther beaks recurved; pod 3–5 cm long"	"Senna barclayana"
6	"Petiole 25–50 mm long; leaflets 15–25 mm wide; anther beaks incurved; pod 7–10 cm long"	"Senna planitiicola"
7	"Leaflets in 1–3 pairs"	8
7	"Leaflets in 4–8 pairs"	10
8	"Seeds without areoles; plants woody, shrubby"	"Senna pendula"
8	"Seeds with areoles; plants ±herbaceous"	9
9	"Anthers 7, beaked; petiole 15–20 mm long; pedicels 15–20 mm long; areole oblique"	"Senna obtusifolia"
9	"Anthers 7 or 10, truncate; petiole 20–45 mm long; pedicels c. 10 mm long; areole longitudinal"	"Senna tora"
10	"Gland 1 between the basal pair of leaflets"	"Senna pendula"
10	"Glands 2–4 between the lower pairs of leaflets"	11
11	"Plants pubescent; leaflets in 6–8 pairs, recurved at the margins"	"Senna multiglandulosa"
11	"Plants glabrous; leaflets in 4–5 pairs, flat"	"Senna x floribunda"
12	"Fertile anthers 2, 6 or 7 (sometimes 10 in S. siamea ), often beaked, the 2 or 3 abaxial anthers markedly larger and borne on filaments often elongate and widely divergent; leaf rachis usually eglandular (sect. Senna )"	13
12	"Fertile anthers 10, rarely 7 (in S. heptanthera ), truncate, subequal; filaments short and straight, the 1–3 abaxial ones sometimes slightly longer; leaf rachis with glands between the lower leaflet pairs at least (sect. Psilorhegma)"	20
13	"Inflorescences forming a loose, many-flowered panicle in upper axils"	14
13	"Inflorescences dense, axillary and/or terminal"	15
14	"Stipules minute, subulate, persistent; leaflet pairs (10–) 15–25 mm apart; petals 15–20 mm long; pod 15–30 cm long; tree to 30 m tall"	"Senna siamea"
14	"Stipules acicular, caducous; leaflet pairs 5–7 mm apart; petals to 8 mm long; pod 7–9 cm long; shrub to 2 m tall"	"Senna timorensis"
15	"Floral bracts dark brown or black"	"Senna didymobotrya"
15	"Floral bracts yellow, yellow-brown, orange or green"	16
16	"Pod 12–16 cm long, with lateral wings"	"Senna alata"
16	"Pod 2.5–10 cm long, without lateral wings"	17
17	"Leaves usually distinctly hairy; foliar glands present, small"	18
17	"Leaves not distinctly hairy; foliar glands absent"	19
18	"Floral bracts pubescent, acuminate, caducuous, green"	"Senna notabilis"
18	"Floral bracts glabrous, obtuse, persistent, yellow"	"Senna venusta"
19	"Leaflets emarginate, broadly oblong to orbicular, 30–50 mm wide"	"Senna magnifolia"
19	"Leaflets obtuse and mucronate to emarginate, linear to elliptic, never more than 20 mm wide"	"Senna pleurocarpa"
20	"Pod with ridges on the inner faces of the valves, flat or plump; seeds glossy or lustrous; leaves usually not sclerophyllous"	21
20	"Pod without ridges on the inner faces of the valves, flat; seeds dull or rarely lustrous; leaves usually highly modified and/or sclerophyllous"	28
21	"Petioles (10–) 15–65 mm long"	22
21	"Petioles 2–15 mm long"	26
22	"Pod 5–10 mm wide, sometimes oval in T.S."	23
22	"Pod 10–25 mm wide, quite flat"	24
23	"Leaflets narrowly elliptic, 3–8 mm wide; pod usually curved or coiled through 1/2–3/4 of a circle; flowers 5–8 per peduncle"	"Senna costata"
23	"Leaflets broadly elliptic, 10–15 mm wide; pod curved through 1/4 of a circle; flowers 2–5 per peduncle"	"Senna acclinis"
24	"Leaflets in 6–10 pairs, discolorous"	"Senna surattensis"
24	"Leaflets in 2–6 (–7) pairs, concolorous"	25
25	"Longest petals 15–30 mm long; petiole 20–65 mm long; longest leaflets 40–70 (–100) mm long"	"Senna surattensis"
25	"Longest petals 10–15 mm long; petiole 10–30 mm long; longest leaflets 20–50 (–60) mm long"	"Senna gaudichaudii"
26	"Peduncles 10–30 mm long; glands only between the lowermost 1 or 2 pairs of leaflets"	"Senna coronilloides"
26	"Peduncles 20–90 mm long; glands between all pairs of leaflets"	27
27	"Petioles mostly less than 5 mm long; leaflets linear to narrowly elliptic, usually revolute at the margins, 1–4 mm wide; usually pubescent"	"Senna aciphylla"
27	"Petioles more than 5 mm long; leaflets lanceolate to elliptic, rarely slightly recurved at the margins, 5–10 mm wide; not obviously pubescent, sometimes sparsely hairy"	"Senna barronfieldii"
28	"Petals 11–19 mm long"	29
28	"Petals 4–c. 10 mm long"	36
29	"Leaflets mostly more than 10 mm wide"	30
29	"Leaflets mostly less than 10 mm wide"	32
30	"Foliar glands flat; petiole robust; midrib of the leaflets raised and orange-brown below"	"Senna ferraria"
30	"Foliar glands erect, clavate or conical or hair-like; petiole not robust; midrib of the leaflets not raised and orange-brown below"	31
31	"Peduncles with 2–3 flowers; leaflets broadly elliptic"	"Senna leptoclada"
31	"Peduncles with 5–8 flowers; leaflets narrowly elliptic to lanceolate"	"Senna procumbens"
32	"Petiole 40–100 mm long; leaflets usually lacking or in 1 (–2) pairs, when present terete or compressed, c. 1 mm diam."	"Senna charlesiana"
32	"Petiole less than 45 mm long; leaflets in 3–7 pairs, mostly more than 1 mm wide"	33
33	"Plants with leaflets elliptic to broadly elliptic, more than 4 mm wide, pruinose; and stipules broadly falcate, foliaceous, persistent"	"Senna glutinosa subsp. pruinosa"
33	"Plants not having this complete combination of characters"	34
34	"Plants with foliar glands stalked, pointed; and stipules acicular, ±persistent; and leaves narrowly elliptic, 1–4 mm wide; and petals consistently hairy outside"	"Senna glutinosa subsp. chatelainiana"
34	"Plants not having this complete combination of characters"	35
35	"Plants viscid; and leaflets elliptic, mostly distinctly longer than the distance between successive pairs; and stipules acicular, caducous; and foliar glands sessile, flat"	"Senna glutinosa"
35	"Plants not having this complete combination of characters"	"Senna glutinosa subsp. x luerssenii"
36	"Leaflets absent or in 1–4 pairs"	37
36	"Leaflets in 5–14 pairs"	68
37	"Petals mostly 4–6 mm long"	38
37	"Petals 6–10 mm long"	40
38	"Low shrub to 0.3 m tall; leaflets increasing in size distally, the pairs 4–10 mm apart"	"Senna curvistyla"
38	"Shrub or small tree 0.4–2 m tall; leaflets equal or decreasing in size distally, the pairs 1–5 mm apart"	39
39	"Leaflets linear, tightly recurved, appearing terete"	"Senna manicula"
39	"Leaflets linear to narrowly spathulate, flat"	"Senna cardiosperma"
40	"Plants to 0.3 m tall; perennial herbs or shrubs or prostrate or creeping"	41
40	"Plants more than 0.5 m tall, shrubs or trees, erect or spreading"	43
41	"Stipules cordate, persistent"	"Senna cladophylla"
41	"Stipules acicular, caducous"	42
42	"Leaflets 5–12 mm long; fertile anthers 10"	"Senna hamersleyensis"
42	"Leaflets 20–50 mm long; fertile anthers 7"	"Senna heptanthera"
43	"Petiole to 6 mm long"	44
43	"Petiole at least 6 mm long"	45
44	"Leaflets narrowly elliptic to elliptic; inflorescences usually 2-flowered, produced along the branches"	"Senna goniodes"
44	"Leaflets obovate; inflorescences 3–5-flowered, produced near the ends of the branches"	"Senna symonii"
45	"Petiole laterally compressed"	46
45	"Petiole terete"	47
46	"Phyllodes falcate, densely appressed sericeous-tomentose; pods 10-13 mm wide, strongly curved to form one third to half a circle"	"Senna phyllodinea"
46	"Phyllodes straight or slightly curved, sparsely to moderately pubescent with minute, appressed hairs; pods (6-)7-8(-9) mm wide, straight or slightly curved"	"Senna artemisioides subsp. x petiolaris"
47	"Mature leaves usually without leaflets"	"Senna circinnata"
47	"Mature leaves with leaflets"	48
48	"Leaflets terete or laterally compressed"	49
48	"Leaflets dorsiventrally flattened and/or channelled above"	52
49	"Leaflets laterally compressed"	50
49	"Leaflets terete"	51
50	"Phyllodes falcate, densely appressed sericeous-tomentose; pods 10-13 mm wide, strongly curved to form one third to half a circle"	"Senna phyllodinea"
50	"Phyllodes straight or slightly curved, sparsely to moderately pubescent with minute, appressed hairs; pods (6-)7-8(-9) mm wide, straight or slightly curved"	"Senna artemisioides subsp. x petiolaris"
51	"Leaflets in 1–4 pairs, 20–40 mm long; petiole 15–25 mm long"	"Senna artemisioides subsp. filifolia"
51	"Leaflets in 3–8 pairs, 15–25 mm long; petiole 6–15 mm long"	"Senna artemisioides"
52	"Leaflets more than 5 times longer than wide"	53
52	"Leaflets less than 5 times longer than wide"	58
53	"Leaflets inrolled, completely enclosing the upper surface and/or channelled above"	"Senna artemisioides"
53	"Leaflets with the upper surface visible"	54
54	"Petiole 15–25 mm long"	"Senna artemisioides subsp. quadrifolia"
54	"Petiole 6–15 (–20) mm long"	55
55	"Leaflets incurved or inrolled at the margin"	56
55	"Leaflets flat or recurved at the margin"	57
56	"Leaflets in 1–2 pairs, 18–40 mm long, glabrous or very sparsely pubescent, glaucous"	"Senna artemisioides subsp. zygophylla"
56	"Leaflets in 2–8 pairs, 15–25 mm long, grey-pubescent, not glaucous"	"Senna artemisioides subsp. x sturtii"
57	"Leaflets in 4–7 pairs, narrowly to broadly elliptic, acute; petals rarely less than 11 mm long"	"Senna glutinosa subsp. x luerssenii"
57	"Leaflets in 2–5 pairs, linear, rounded; petals 8–10 mm long"	"Senna stricta"
58	"Leaflets mostly more than 8 mm wide"	59
58	"Leaflets mostly less than 8 mm wide"	63
59	"Leaflets densely woolly-hairy"	"Senna artemisioides subsp. helmsii"
59	"Leaflets pubescent to glabrous"	60
60	"Pod curved, crenate; inflorescences borne along the stems"	61
60	"Pod straight or slightly curved, not crenate; inflorescences borne near the ends of the stems"	62
61	"Inflorescence 2- or 3-flowered; petiole 4–10 mm long; leaflets acute"	"Senna goniodes"
61	"Inflorescence mostly 3–5-flowered; petiole 8–15 mm long; leaflets acute to rounded"	"Senna oligoclada"
62	"Leaflets presented ±vertically, with adaxial surfaces exposed; leaflet pairs 8–12 mm apart"	"Senna artemisioides subsp. alicia"
62	"Leaflets presented ±horizontally; leaflet pairs 15–25 mm apart"	"Senna artemisioides subsp. oligophylla"
63	"Leaflets slightly to distinctly recurved at the margin"	64
63	"Leaflets flat or inrolled at the margin"	66
64	"Leaflets densely woolly-hairy"	"Senna artemisioides subsp. helmsii"
64	"Leaflets glabrous to sparsely appressed-hairy, or pubescent"	65
65	"Leaflets glaucous with a reddish tinge, often acute, in 2–4 pairs"	"Senna glaucifolia"
65	"Leaflets usually glaucous, lacking reddish tinge, obtuse, usually in 2–6 pairs"	"Senna artemisioides subsp. x coriacea"
66	"Leaflets moderately to densely silky or woolly-hairy, inrolled at the margin"	"Senna artemisioides subsp. x sturtii"
66	"Leaflets glabrous or sparsely appressed-hairy, not inrolled at the margin"	67
67	"Leaflets presented ±vertically, with adaxial surfaces exposed; leaflet pairs 8–12 mm apart; petiole 8–10 mm long"	"Senna artemisioides subsp. alicia"
67	"Leaflets presented ±horizontally; leaflet pairs 1–8 mm apart; petiole 3–8 mm long"	"Senna symonii"
68	"Leaflets terete"	69
68	"Leaflets flat, concave or inrolled"	70
69	"Petiole less than 5 mm long; leaflet pairs less than 5 mm apart"	"Senna cardiosperma subsp. microphylla"
69	"Petiole more than 5 mm long; leaflet pairs more than 5 mm apart"	"Senna artemisioides"
70	"Petals 4–8 mm long; petiole mostly 1–4 mm long"	71
70	"Petals 7–10 mm long; petiole mostly 5–60 mm long"	74
71	"Leaflets densely woolly, at least on the underside"	"Senna cuthbertsonii"
71	"Leaflets with sparse, soft, erect hairs"	72
72	"Peduncle 25–35 mm long, often exceeding the leaves"	"Senna pilocarina"
72	"Peduncle to 5 mm long, not exceeding the leaves"	73
73	"Leaflets in 5–10 pairs, 3–6 mm long, 2–4 mm wide"	"Senna cardiosperma subsp. gawlerensis"
73	"Leaflets mostly in 9–14 pairs, mostly 6–10 mm long, 1–4 mm wide"	"Senna stowardii"
74	"Leaflets in 10–13 pairs"	"Senna flexuosa"
74	"Leaflets in 1–8 pairs"	75
75	"Leaflets inrolled, enclosing the upper surface or channelled above"	"Senna artemisioides"
75	"Leaflets with the upper surface visible"	76
76	"Leaflets moderately to densely silky to woolly-hairy"	"Senna artemisioides subsp. x sturtii"
76	"Leaflets glabrous or sparsely hairy"	77
77	"Leaflets usually 7–15 mm long, less than 5 times longer than wide"	"Senna artemisioides subsp. x coriacea"
77	"Leaflets 10–25 mm long, more than 5 times longer than wide"	78
78	"Leaflets narrowly to broadly elliptic, acute"	"Senna glutinosa subsp. x luerssenii"
78	"Leaflets linear, blunt"	"Senna stricta"