Arborescent shrubs, closely resembling plurifoliolate forms of C. surinamensis in habit, indumentum, and inflorescence but markedly different in ampler perianth. Stipules of primary lvs ±5-6 x 2 mm, striate. Lf-formula i/17-19; lf-stks of primary lvs 4-6 x 0.7-1.1 mm, of brachyblast lvs scarcely shorter; pinna-rachis in primary lvs 6-7.5 cm, the longer interfoliolar segments ±3-4.5 mm; lft-pulvinules 0.50.7-0.8 mm; lfts a little decrescent at each end of rachis, otherwise subequilong, the blades lance-ellipitic from semicordate base, deltately acute apiculate, those near mid-rachis 11-12.5 x 4-4.5 mm, ±2.7-2.8 times as long as wide; midrib only a trifle excentric, the inner of 3(-4) posteRíor primary nerves produced ± to mid-blade. Peduncles stout 14-16 mm, bracteate below middle; capitula ±10—16-fld, the receptacle 2 mm diam; bracts lanceolate 1.5-2 mm; pedicels 0.6 x 0.7-1 mm; fls homomorphic, the perianth thinly sordid-strigulose, the calyx weakly striate, the membranous corolla not so; calyx ±6x3 mm, the ovate-triangular teeth 2-2.8 mm; corolla 13-14.5 mm, the lobes 3.4-4 mm; androecium of all fls 34-merous, ±41 mm, the far-exserted tube 26 mm, slightly dilated distally; no disc observed; ovary and pod unknown.

On banks of rapidly flowing stream, ±225 m, known only from the type-locality in the middle Marañón basin, near 4°30'S, 78°15'W in prov. Bagua of depto. Amazonas, Peru. — Fl. XII—I, probably at other times. — Samik.

Calliandra samik closely resembles the polymorphic C. surinamensis in foliage and indumentum and may prove to be merely another extreme variant of it. However, the much longer perianth (for measurements see the Latin diagnosis above) can hardly be accommodated in my present concept of C. surinamensis.