Slender trees 3(-?) m, glabrous throughout, the ample coriaceous lfts moderately bicolored, when dry dull brown-olivaceous, the solitary or geminate fl- spikes borne on branchlets either close below homoti- nous foliage or perhaps at anthesis axillary to coeval lvs. Stipules unknown. Lf-formula i/(-l)l½, the lfts (4-)6 per lf; petioles ±7-11 x 1-2 mm, shallowly grooved ventrally, charged near top with an impressed cuneiform nectary to 3.5 mm; rachis of pinnae 2-2.7 cm, the lower posterior 1ft somewhat below middle; lft-pulvinules ±1.5-2 mm; lfts elliptic or ovate-elliptic from inequilaterally cuneate base, obtuse or shortly obtusely acuminate, the blades of distal pair ±5.5-7 x 2.2-3.1 cm, 2-2.5 times as long as wide; venation pinnate, the slightly excentric, dorsally prominulous, nearly straight midrib giving rise on each side to ±7-10 fine secondary veins weakly brochidodrome close within the plane margin, the fine tertiary and reticular venules perceptible but immersed. Axis of inflorescence units, including short peduncles, (3.3-) 4—8 cm, the fls crowded; bracts minute, deciduous; fls sessile; perianth not seen, described (ex char.) as white and highly fragrant, the calyx scarcely 1 mm, the striate corolla to 4 mm, the androecial tube included. Pods sessile, in profile falcately oblong, obtuse at each end, 7-9.5 x 2-2.2 cm, planocompressed, ±8-seeded, the sutures <1.5 mm wide in dorsal view, sinuously impressed only where an ovule aborts, the leathery-crustaceous valves yellowish green turning castaneous, smooth but not lustrous, in section ±0.5 mm thick; dehiscence not seen; seeds uniseriate along the cavity, well separated, plumply discoid 12-14 mm diam, the testa papery, dull brown, pleurogram 0.

In campo with scattered crooked trees (cerrado) at ±150 m, local on both sides of the lower Guaporé River 12°-12°30'S, 64°-64°30'W, in Rondônia, Brazil (downstream from Principe de Beira) and adj. Beni, Bolivia (prov. Iténez). — Not mapped. — Fl. VI-?; fr. III-IV.

We have associated Z. odoratissima with Z. bangii, which share the feature, unusual in Zygia, of axillary, not cauliflorous, flower-spikes. The thin-walled pod resembles that of Z. cataractae rather than that of most other spicate zygias.