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Trees, shrubs and often climbers, armed or unarmed. Leaves bipinnate or apparently simple, sometimes modified to phyllodes, petioles often with basal glands, stipules spinascent or not. Flowers in axillary pedunculate heads or cylindrical spike, bisexual or unisexual. Sepals united, 4-5 lobed. Petals united, 4-5 lobed. Stamens numerous, filaments free at the base, anthers with a stipitate gland at the apex. Pods variable in form and size, endocarp not separate from the exocarp. Seeds with hard testa, smooth, glossy and without endosperm.

Key to the species

Serial Key Reference
1a. Plants unarmed; leaves modified to phyllodes 2
1b. Plants armed; leaves not modified to phyllodes or leaves pinnately compound 3
2a. Flowers golden yellow; phyllodes with 3 main veins; calyx campanulate, glabrous A. auriculiformis
2b. Flowers white or creamy-white; phyllodes with 4 main veins; calyx broadly cupular, pubescent to tomentose A. mangium
3a. Plants trees; flowers bright yellow 4
3b. Plants scandent shrubs to woody climbers; flowers creamy-white 5
4a. Plants trees; leaflets 10-30 pairs; corolla puberulous; pods strap-shaped, flattened, deeply constricted between seeds A. nilotia
4b. Plants shrubs or small trees; leaflets 10-20 pairs; corolla glabrous; pods cylindric to oblong, not deeply constricted between seeds A. farnesiana
5a. Inflorescence axillary; pods oblong, often with sinuate margin and constricted; dark brown to blackish in colour A. concinna
5b. Inflorescence terminal; pods strap-shaped, faintly sinuate along the margin without constricted; dark reddish-brown to coppery A. pennata