Zygia cognata

Title

Zygia cognata

Authors

Rupert C. Barneby

Scientific Name

Zygia cognata (Schltdl.) Britton & Rose

Description

36. Zygia cognata (Schlechtendal & Chamisso) Britton & Rose, N. Amer. Fl. 23: 39. 1928. Inga cognata Schlechtendal & Chamisso, Linnaea 12: 560. 1838. -"[MEXICO. Veracruz:] in regione calida inter Colipam et littora maris [on the Gulf lowlands near 19°55'N, 96°40'W]... (Schiede)." — Holotypus, C. W. Schiede 676 in HAL 71728!. — Inga (?) sp., Schlechtendal & Chamisso, Linnaea 5: 592. 1830. — Pithecolobium cognatum (Schlechtendal & Chamisso) Bentham, London J. Bot. 5: 107. 1846. — Feuilleea cognata (Schlechtendal & Chamisso) O. Kuntze, Revis. Gen. Pl. 1: 187. 1891.

Inga stevensonii Standley, Trop. Woods 23: 7. 1930. — "BRITISH HONDURAS: Freshwater Creek, March, 1928, D[uncan\ Stevenson (II) 65." — Holotypus, F 584345!; clastotypus (fls.), NY!; isotypus, Y n.v. — Zygia stevensonii (Standley) Record, Trop. Woods 63: 6. 1940. — Pithecolobium stevensonii (Standley) Standley & Steyermark, Publ. Field Mus. Nat. Hist. 23: 164. 1944. Pithecolobium cognatum sensu Standley, 1922: 394 quoad nom., vix descr.

Pithecolobium stevensonii sensu Standley & Steyermark, 1946: 82.

Macrophyllous trees 3-8 m with scaley trunk(s) and terete brownish lenticellate branches, the young stems and lf-axes often brownish-puberulent, but the stiffly papery lfts glabrous, the foliage when dry dull brownish-olivaceous, paler beneath, the loose capitula or short racemiform spikes of whitish fls arising from knots on trunk and branches, below the current lvs. Stipules lanceolate or ovate-triangular 1.5-6 mm, weakly striate when young, soon firm smooth, deciduous. Lf-formula i/2½-4½(-6½); lf-stks 4—9(-15) x 1.5-6 mm, charged at top with a sessile buttonlike nectary ±1-2.5 mm diam; similar but smaller nectaries at insertion of some lfts; rachis of longer pinnae 7-17(-20) cm, the longer interfoliolar segments 2-5.5 cm; lft-pulvinules (2-)2.5-5.5(-7) mm; lfts accrescent distally, the blades elliptic or ovate-elliptic from inequilaterally cuneate base, either acutely or obtusely short-acuminate, the distal pair (8-) 11-22 (-27) x (3-)4-8 cm, 2.4-3.3 times as long as wide; midrib subcentric, straight or gently incurved, giving rise on each side to 7-9 major incurved-ascending secondary nerves, the tertiary connecting and reticular venules prominulous on both faces. Units of inflorescence 9—18-fld, the peduncle 2—12 mm, the floral axis 3-16 mm; bracts ovate 0.6-1.2 mm, persistent; pedicel 0-1.2 x 0.45-0.6 mm; perianth (4-)5-merous; calyx shallowly or deeply campanulate 1.2-2.3 x 1-1.3 mm, the teeth 0.1-0.4 mm, often rudimentary; corolla tubular, scarcely dilated distally, 7—10.5 mm, the ovate, often unequal lobes 0.9-1.4 mm; androecium 17.5-20 mm, 42-60-merous, the tube 9.5-12.5 mm (exserted 0.5—3.5 mm), the stemonozone obscure, the intrastaminal nectary 0.35-0.5 mm; ovary at anthesis glabrous. Pods either sessile or shortly stipitate, in profile broad-linear, straight or almost so, when well fertilized 13-25 x 1.9—2.4 cm, 9—16- seeded, laterally compressed but becoming plumply biconvex and often low-corrugate lengthwise, bicarinate by straight or low-undulate sutures, the lignescent valves densely minutely strigulose-tomentulose overall with brown or golden-brown hairs; dehiscence through both sutures, the valves narrowly gaping; seeds imbricate along the cavity, plumply disciform, in broad view ±24 x 18-20 mm, the testa papery brittle, lustrous dark-castaneous, loosely enveloping the embryo, pleurogram 0.

In wet forest and on riverbanks and wooded shores, 5-300 m, local in SE Mexico (Veracruz, on Gulf lowlands below 20°N; N Oaxaca; Usumacinta valley in N Chiapas; Caribbean coast of Quintana Roo), NE Guatemala (Petén), and N Belize (Orange Walk and Belize distr.). — Map 30. — Fl. II—VIII; fr. ripe I—II, VII-VIII, probably nearly throughout the year.

Without the fruit Z. cognata is scarcely distinguishable from Z. peckii, but the leaflets are commonly more numerous by 1-2 pairs.