Tree, to 15 m tall; branchlets ferruginous-pilose when young, glabrate in age. Leaves sparsely pilose on axis and veins; petioles 5-40 mm long; rachis conspicuously winged; leaflets in 2-4 (5) pairs, ovate-elliptic to obovate, acuminate to broadly acute, acute to rounded at base, usually asymmetrical, the terminal pair 7-14 cm long, 3-6 cm wide. Spikes 1 to several per axil; peduncles very short or to 1.5 cm long, strigose; rachis strigose, 1.5-2.5 cm long; flowers sessile; bracts ca 3 mm long; calyx 7-10 mm long, puberulent but with pilose base, longitudinally striate, the lobes acute to subacute, 1-2 mm long; corolla 10-19 mm long, densely white-sericeous, the lobes narrow, to ca 5 mm long; stamens and style to ca 45 mm long. Legumes flat until nearly fully mature, 4-15 cm long, 1.5-2.5 cm wide, strigose, usually with low, thin, transverse wrinkles. Zetek 3497. Easily confused with I. pauciflora, except in fruit, and sometimes with I. vera. Known only from Panama, from tropical moist forest on the Pacific slope in the Canal Zone, Panama, and Darien and from premontane wet forest in Panama (Cerro Azul).