Zygia juruana

Title

Zygia juruana

Authors

Rupert C. Barneby

Scientific Name

Zygia juruana (Harms) L.Rico

Description

29. Zygia juruana (Harms) L. Rico, Kew Bull. 46: 501. 1991. Pithecolobium juruanum Harms, Verh. Bot. Vereins Prov. Brandenburg 48: 162. 1907. — "Brasilien: Amazonas-Gebiet, im Walde bei Marary, Jurua (E. Ule no. 5062—Sept. 1900)." — Holotypus, †B = F Neg. 1202!; isotypus, K!.

Macrophyllidious cauliflorous trees 4-20 m with terete pallescent branchlets, except for brownish- puberulent inflorescence and nascent innovations glabrous throughout, the ample, stiffly papery lfts when dry lustrously brown-olivaceous above, a little paler dull beneath, the inflorescence composed of condensed capitula arising either directly from knots on trunk and branchlets or assembled into short efoliate pseudoracemes. Stipules (deciduous, little known) triangular-lanceolate 1-2.5 mm, sometimes basally thickened, not striate. Lf-formula 1/1½-2½ (-3½), the lfts mostly 3 or 5 per pinna, the whole lf 6-10(-14)- foliolate, the proximal pair(s) either opposite or not; lf-stk very short and stout, including pulvinus 4.5-8 x 2-5 mm; nectary at tip of lf-stk sessile, round or rhombic 1.8-3.2 mm diam, a similar smaller nectary at tip of each pinna and between lf-pairs when these are opposite; rachis of pinnae 4—12(—15) cm, one of the pair often shorter than the other, the furthest interfoliolar segments 2.5-9 cm, the proximal one much shorter; pulvinules (3-)4—8 mm, becoming grossly wrinkled; lft-blades broadly lance- to ovate- elliptic from inequilaterally narrow-cuneate base, shortly acuminate, the distal pair 12-24(-27) x 5-10 cm, (2.1-)2.3-3.3 times as long as wide; venation pinnate, the dorsally prominent, subcentric and (nearly) straight midrib giving rise on each side to ±5-8 major (and few intercalary) secondary nerves weakly brochidodrome well within the plane or weakly revolute margin, the first 1 or 2 secondaries on posterior side of midrib not or scarcely longer and stronger than the rest, the tertiary and reticular venulation immersed or almost so above, weakly prominulous beneath. Inflorescence when fully developed a short simple pseudoraceme of 6-14-fld capitula, but the primary axis often not extended and the individual peduncles emergent directly from knots; peduncles 3-13 mm, the receptacle ±1.5-4 mm; bracts <1 mm, persistent; fls sessile, the whitish or red-tinged perianth puberulent overall, the calyx externally veinless, the corolla-tube faintly striate; calyx deeply campanulate (2-)2.5-6 x 1.4—2 mm, the teeth 0.4 mm or less; corolla subcylindric 7-9 mm, the lance-ovate, often unequal lobes 0.9-2.1 mm; androecium 40-60-merous, 16-19 mm, the tube 7.5-10.5 mm, exserted 0-2 mm, the tassel pink or carmine; intrastaminal nectary 0.4—0.45 mm; ovary at anthesis glabrous; stigma poriform. Pods solitary, sessile, narrowly oblong ±10-13 x 3.5-4 cm, shallowly lunate or almost straight, the stout sutures scarcely prominent, very shallowly if at all undulate, the nearly plane, rigidly pithy-lignescent valves becoming when ripe dull brown, smooth or finely wrinkled-tumulose but not venose, glabrous; dehiscence tardy, along both sutures, the valves narrowly gaping to release the seeds; seeds (of sect. Zygia, few seen) in broad view ±2.5 cm diam.

In seasonally flooded forest (tahuampa, várzea) below 200 m, of seemingly bicentric dispersal: scattered on upper affluents of the Amazon in NE Peru (Loreto) and equatorial W Brazil (Amazonas, Acre); and on the lower Amazon and immediate tributaries in Pará. — Map 26. — Fl. VI-IX; fr. XII-III. — Jarandeua da folha grande.