Leucaena pallida is a small deciduous multiple-stemmed tree 3-7 m tall although occasionally to 10 m tall and a bole diameter of 10-15 (-30) cm, with an open, spreading or narrow crown. Bark smooth, metallic-grey, blotched lighter grey with horizontally aligned pale brown lenticels, slash greenish. Leaves have 15-27 pairs of pinnae, pinnular rachis 8-11 cm long, sparsely hairy, leaflets 6-8(-10) mm long, 1-2 mm wide, 39-50 pairs per pinna, asymmetric truncate at base, linear or oblong, acuminate at apex. Petiole gland unstalked, shallow crater-shaped, elliptical, 3-4 mm long by 2-3 mm wide. Flower head 14-16 mm in diameter, 95-110 flowers per head, in groups of 3-5 in leaf axils on actively growing shoots, sometimes with suppression of leaves on the flowering shoot, flowers appear pale pink or dull purplish mauve. Pods 12-19 cm long, 14-18 mm wide, 3-5 per flower head, linear, slightly thickened and leathery, glossy maroon when unripe, turning reddish-brown, glabrous or occasionally hairy. Seed 5-7 mm wide, 6-8 mm long, slightly rhombic aligned transversely in pods. The specific epithet means pale in reference to the flowers.