1	"Inflorescences spicate"	2
1	"inflorescences capitate"	3
2	"Inflated spines deeply constricted near the base; corollas 3-3.5 times as long as the calyces; pods straight; plants usually trees with a well-defined trunk"	"Vachellia bussei"
2	"Inflated spines not or only slightly constricted at the base; corollas 2-2.5 times as long as the calyces; pods curved; plants shrubs, branching from near the ground"	"Vachellia horrida"
3	"Some pairs of stipular spines fused at the base into an inflated, rounded or bilobed, ultimately woody structure"	4
3	"Stipular spines not inflated"	6
4	"Flowers white or cream; pods 4-7 cm long"	"Vachellia drepanospermum"
4	"Flowers bright yellow; pods mostly 7-20 cm long"	5
5	"Calyces 0.8-1.5 cm long"	"Vachellia zanzibarica"
5	"Calyces 2-2.5 cm long"	"Vachellia seyal"
6	"Flowers bright or golden yellow"	7
6	"Flowers white, cream, pale yellow, or pink"	8
7	"Bark or trunk yellowish, becoming powdery; epidermis of branchlets flaking off to expose a greenish-yellow inner layer; pods with thin valves"	"Vachellia xanothophloea"
7	"Bark of trunk not as above; epidermis of branchlets not flaking off; pods with thick valves"	"Vachellia nilotica"
8	"Many or all spines short and hooked or recurved, often intermixed with longer straight spines"	9
8	"All spines straight or nearly so, varying in length"	11
9	"Pods contorted or spirally twisted or, if straight or almost so, at least 12 cm long and leaves densely pubescent"	"Vachellia tortilis"
9	"Pods straight, usually less than 10 cm long; leaves sparsely pubescent"	10
10	"Branches usually with long straight and short curved spines intermixed; leaves with 1-9(-17) pairs of pinnae, usually at least some leaves with more than 4 pairs; plants trees, usually with well-marked trunks"	"Vachellia etbaica"
10	"Branches only with short hooked spines; leaves with 1-3 pairs of pinnae; plants usually shrubs that branch from near the base"	"Vachellia reficiens"
11	"Young branchlets villous with spreading hairs 0.75-3 mm long"	12
11	"Young branchlets glabrous or with shorter hairs, sometimes somewhat woolly"	13
12	"pods 6-12 cm long, 0.6-1 cm wide, dehiscent, coriaceous, attenuate at both the tip and the base; calyces and bracteoles glabrous or almost so"	"Vachellia paolii"
12	"Pods usually 2-4.5 cm long, 1-1.5 cm wide, indehiscent, thick and woody, less attenuate; calyces more or less pubescent outside; bracteoles ciliate or pubescent"	"Vachellia stuhlmannii"
13	"Leaflets 6-15 mm long and 3.5-9 mm wide; leaves with 2(-3) pairs of pinnae, the proximal pair much shorter than the distal pair"	"Vachellia walwalensis"
13	"Leaflets up to (7-) 9 mm long and 2(-4) mm wide; leaves usually with more than 2 pairs of pinnae but, if 2, then the proximal pair not much shorter than the distal pair"	14
14	"Corolla lobes glabrous or almost so on the outside"	15
14	"Corolla lobes conspicuously hairy on the outside"	16
15	"Pods distinctly curved"	"Vachellia robusta"
15	"Pods straight or almost so"	"Vachellia etbaica"
16	"Young branchlets, leaves, and pods clothed with a dense white woolly indumentum; leaflets so small and compressed that the pinnae resemble crenulate leaflets; seeds without areoles"	"Vachellia leucospira"
16	"Young branchlets, leaves, and pods glabrous to tomentose but not covered with a white indumentum; leaflets usually not as above; seeds with areoles"	17
17	"Pods with markedly thickened and woody valves, usually curved but sometimes almost straight; branchlets yellowish to purplish brown"	"Vachellia edgeworthii"
17	"Pods not markedly thickened and woody, usually straight, sometimes slightly curved; branchlets white, greyish-white, or yellowish-green"	"Vachellia oerfota"