Zygia morongii Barneby & J.W.Grimes
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. & Grimes, James W. 1997. Silk tree, guanacaste, monkey's earring: A generic system for the synandrous Mimosaceae of the Americas. Part II.
, , and . Mem. New York Bot. Gard. 74: 1-149. -
Family
Mimosaceae
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Scientific Name
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Type
Paraguay. Gran Chaco, 31 Dec. 1888 (fl., fr.), T. Morong 360. — Holotypus, NY; isotypus, NY. — Paratypi, Paraguay. Central: in regione lacus Ypacaray, May 1913 (fl.), T. Rojas in Hassler 12635, G, NY. Argentina. Corrientes, Apr 1956 (fl.), T M. Pedersen 3
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Description
Species Description - Freely branched, macrophyllidious arborescent shrubs 3-10 m with pallid terete annotinous branchlets, the young stems and lf-axes thinly (seldom more densely) pilosulous or puberulent but often glabrate in age, the lfts (dry) bicolored, brown-olivaceous sublustrous above, a little paler beneath, glabrous except in vernation, the loose capitula of white, pink-stamened fls shortly pedunculate from defoliate knots on annotinous and older wood (rarely also from a few annotinous, still foliate nodes). Stipules triangular or lanceolate 1-5 mm, firm subpersistent, weakly ±5-nerved only when young. Lf-formula i/l½(-2½), the lfts in most lvs exactly 6, in random lvs 8 or 10; petioles 3-6 x 1.4-2 mm; nectary near tip of lf-stk sessile, plane or shallowly cupular 1-1.6 mm diam, a smaller one at tip of each pinna-rachis; rachis of pinnae 1.3-4 cm, the 1 (or longer of 2) interfoliolar segments 1-2.2 cm, the small odd posterior lft inserted close above pinna- pulvinus; lft-pulvinules 1.7-3 x 0.8-1.5 mm; lfts inequilaterally elliptic or ovate-elliptic from asymmetrically cuneate or shallowly semicordate base, very shortly obtusely acuminate, the distal pair 4-8.5(-10) x 2-3.8(-5) cm, ±2-2.3 times as long as wide; venation pinnate, the straight, slightly excentric midrib giving rise on each side to 5-8 incurved-ascending secondary nerves feebly brochidodrome well within the plane margin, these and the tertiary and reticular venules prominulous on both faces of blade but more sharply so beneath. Peduncles 1.5-6 mm; capitula 3-14-fld, the axis 1.5-3 mm; bracts 0.5-0.9 mm, persistent; perianth glabrous except for minute puberulence at mouth of calyx and at tip of corolla-lobes, the calyx weakly 5- or 10-nerved, the corolla-tube finely striate; calyx campanulate (1-) 1.5-3 x 1-1.6 mm, the depressed-deltate teeth often unequal, 0.1-0.4 mm; corolla narrowly trumpet-shaped 5.5-8.7 mm, at top of tube 1.7-2.8 mm diam, the ovate subacute lobes 1.3-2.1 mm; androecium 43-53-merous, 20-23 mm, the tube exserted 0.5-4.5 mm, the tassel pink; stemonozone 1-1.4 mm; disc 0.3-0.6 mm. Pods solitary, sessile, attached laterally above the broadly rounded base, in profile oblong to broad-linear 3-13 x 2-2.9 cm, usually gently recurved, obtuse apiculate, ±3-5- seeded, planocompressed becoming low-convex over seeds, framed by thickened but scarcely prominent sutures, the rigidly pithy-ligneous valves smooth, dull-brown, minutely often densely brownish-puberulent, in section 1.1-2 mm thick; dehiscence follicular, the ventral suture narrowly gaping; seeds subcontiguous but scarcely imbricate, round or elliptic in broad view, ±15-16 mm diam, the testa brown papery, lacking pleurogram.
Distribution and Ecology - In swampy woodlands and riverine forest of the Paraguai-Paraná basin below 120 m, in NE Argentina and centr. Paraguay (within 25°-28°S, 55°30'-59°W): in Argentina from far E Formosa and Chaco E across N Corrientes into SW Misiones; thence weakly N into centr. Paraguay; disjunct in Mato Grosso do Sul (mun. Corumbá) near Ponte do Areião (not mapped). — Map 28.
Relationships - Zygia morongii has been known for a century but has consistently been mistaken for our Z. latifolia var. communis, from which it differs in conventionally pinnate venation of the leaflets and in the lignescent pod. The leaves are compatible with Z. cataractae and the fruits almost with Z. inaequalis, but the combination is alien to both. The leaves are indistinguishable technically from those of the sympatric Z. cataractae, but this has narrower, glabrous flowers, shorter calyces, and the thin-walled pod of its species. Herein we follow Hoc (1981) exactly in delimitation of the two localized zygias that she described and figured as Pithecellobium cauliflorum and P. divaricatum but differ in our interpretation of their affinities and consequently in the nomenclature adopted.
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Common Names
Arbol moneda, granadillo de río, guará-peré
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Distribution
Formosa Argentina South America| Chaco Argentina South America| Corrientes Argentina South America| Misiones Argentina South America| Mato Grosso do Sul Brazil South America| Paraguay South America|