1	"Leaflets 16–37 pairs."	"Senna multijuga"
1	"Leaflets 3–15 pairs."	2
2	"Leaves terete and silvery in colour."	"Senna artemisioides group"
2	"Leaves not terete and not silvery."	3
3	"Gland(s) located at or near the base of the petiole."	4
3	"Glands located between leaflet pairs or absent."	6
4	"Peduncles <6 mm long, pods >9 cm long."	"Senna occidentalis"
4	"Peduncles >9 mm long, pods <9 cm long."	5
5	"Gland on petiole erect, higher than broad."	"Senna clavigera"
5	"Gland on petiole broader than high."	"Senna barclayana"
6	"Glands absent from leaves or inconspicuous beneath thick indumentum."	7
6	"Leaves with glands between leaflet pairs."	9
7	"Floral bracts dark brown or black, persistent."	"Senna didymobotrya"
7	"Floral bracts pale or green, caducous."	8
8	"Plant pubescent except for inner flower parts; leaf glands present but small and inconspicuous below dense indumentum."	"Senna notabilis"
8	"Plant glabrous; glands on leaves absent."	"Senna pleurocarpa"
9	"Flowers with only 6 or 7 anthers fertile (3 upper always reduced or absent), of 2 or 3 different sizes, sometimes beaked; pods cylindrical."	10
9	"Flowers with all 10 anthers fertile, sub-equal, truncate; pods flat."	12
10	"Gland 1 between basal pair of leaflets."	"Senna pendula"
10	"Glands 2–4, between the lower pairs of leaflets."	11
11	"Leaves pubescent, leaflets 6–8 pairs, leaflets acute and mucronate."	"Senna multiglandulosa"
11	"Leaves glabrous, leaflets 4–5 pairs, leaflets with an acuminate apex."	"Senna septemtrionalis"
12	"Petals <11 mm long; seeds dull or rarely lustrous."	"Senna phyllodinea"
12	"Petals greater than or equal to 11 mm long; seeds glossy or dull."	13
13	"Petals pubescent on the outer surface; stipules broadly falcate, persistent; whole plant ± pruinose; pod without ridges on the inner faces of the valves."	"Senna glutinosa"
13	"Petals glabrous on the outer surface, stipules acicular, caducous, plant never pruinose; pod with ridges on the inner faces of the valves."	14
14	"Petioles 20–40 mm long, leaflet pairs c. 15 mm apart on the rachis."	"Senna acclinis"
14	"Petioles 2–15 mm long, leaflet pairs <11 mm apart on the rachis."	15
15	"Peduncles 1–3 cm long; glands only between the lowermost 1 or 2 pairs of leaflets."	"Senna coronilloides"
15	"Peduncles 2–9 cm long; glands between all pairs of leaflets."	16
16	"Petioles mostly less than 5 mm long; leaflets linear to narrow-elliptic, usually revolute at the margins, 1–4 mm wide, usually pubescent."	"Senna aciphylla"
16	"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"