Stryphnodendron rotundifolium Martius (1837: 117)

Scalon, Viviane Renata, Paula-Souza, Juliana De, Lima, Alexandre Gibau De & Souza, Vinicius Castro, 2022, A synopsis of the genus Stryphnodendron (Fabaceae, Caesalpinioideae, mimosoid clade), Phytotaxa 544 (3), pp. 227-279 : 268

33. Stryphnodendron rotundifolium Martius (1837: 117) .

— Type: BRAZIL. Piauí, “Oeiras, Prov. Piauhy”, s.d., Martius s.n. (holotype M 0218772!)

Trees or very rarely shrubs (0.5–)2–6(–9) m tall. Leaves with (5–)6–13(–15) pairs of pinnae; (4–)5-12(–14) pairs of leaflets; petiolar nectary 1, verruciform with an elongated base; leaflets (4–)7–18(–22) × (4–)6–13(–17) cm, usually orbicular, ovate, elliptic or elliptic-ovate, the distal ones usually obovate to sometimes widely obovate, chartaceous sometimes membranaceous-chartaceous or chartaceous-coriaceous, discolor, unilateral tuft of trichomes on the lower surface present, usually prolonged at the midrib. Inflorescences of simple thyrsi, whitish to yellowish, rarely lilac to purplish; cymulae of solitary to 4-ternate spikes; spikes 9–18 cm long. Flowers monoclinous, rarely diclinous, corolla glabrous, white, yellowish white to greenish white. Fruit a nucoid legume, usually straight, rarely slightly curved, turgid, seeds slightly prominent to rarely prominent, valves coriaceous to woody, inconspicuously nerved.

Key to the varieties of S. rotundifolium :

1. Stems glabrous to sparsely pubescent, apex densely ferruginous-pulverulent; petioles glabrous to sparsely pubescent; rachis glabrous to very sparsely pubescent; 2nd degree petiolules usually glabrous, sometimes subglabrous to rarely very sparsely pubescent; rachillae glabrous to sometimes subglabrous; margin of the leaflets glabrous; blade glabrous on both surfaces, sometimes subglabrous along the midrib on the lower surface, sometimes glaucous; prophylls shell-shaped, subsessile, yellow-pubescent ..... ................................................................................................................................................... S. rotundifolium var. rotundifolium

1’. Stems densely velutinous to villous almost up to the apex, turning pubescent and sparsely ferruginous-pulverulent, more densely ferruginous-pulverulent towards the apex, densely ferruginous-pulverulent and pubescent at the apex; petioles pubescent, more densely near the base; rachis pubescent to villous, more densely at the distal part; 2nd degree petiolules pubescent to villous; rachillae villous; margin of the leaflets pubescent to villous; upper surface of the blade subglabrous to sparsely pubescent or villous, lower surface usually sparsely pubescent to villous, sometimes pubescent to villous, rarely densely villous; prophylls spathulate, villous ............................................................................................................................... S. rotundifolium var. villosum