Macrosamanea consanguinea (R.S.Cowan) Barneby & J.W.Grimes

Authors

Rupert C. Barneby

Authority

Barneby, Rupert C. & Grimes, James W. 1996. Silk tree, guanacaste, monkey's earring: a generic system for the synandrous Mimosaceae of the Americas. Part I. Abarema, Albizia, and allies. Mem. New York Bot. Gard. 74: 1-292.

Family

Mimosaceae

Scientific Name

Macrosamanea consanguinea (R.S.Cowan) Barneby & J.W.Grimes

Type

"VENEZUELA: Amazonas: Río Guainía, alt. 120-140 m, clearing at Limoncito, left back of Cano San Miguel 15 km above mouth; 14 Oct 1957, Bassett Maguire, John J. Wurdack & William M. Keith 41878" — Holotypus, US 2267420!; isotypi, GH!, NY!, VEN!

Synonyms

Pithecellobium consanguineum R.S.Cowan

Description

Species Description - Macrophyllidious trees 4—7 m, the young branchlets and lf-axes minutely sordid-pubescent, the ample lvs bicolored, the firm glabrous lfts when dry dark- brown-olivaceous above, pale dull beneath, the long narrow, densely strigulose fls borne in short terminal or sometimes lateral (? cauliflorous) efoliate pseudoracemes of few-fld capitula surpassed by distal lvs. Stipules firm, either triangular or lanceolate 2-3 mm, either persistent or at length deciduous. Lf-formula iii—vii/8—14; lf-stks 8-33 cm, the petiole 2.5-4 cm, at middle 2-4 mm diam, the longer interpinnal segments 2.5-5 cm; nectary near base of petiole sessile patelliform, elliptic 2.5-5 mm in long diam, coarsely callous-marginate, smaller subcircular nectaries at insertion of several distal pinnae and yet smaller ones on rachis between several distal lft-pairs; pinnae accrescent distally, the rachis of penultimate pair 10-18 cm, the longer interfoliolar segments 7-17 mm; 1ft- pulvinules in dorsal view transversely elliptic 0.5-0.8 x 1.3-2 mm, cross-wrinkled; lfts decrescent toward base of rachis and the terminal pair at once longest of all and semi-ovate or -elliptic, the rest subequiform, oblong-trapezoid around a diagonal midrib, obtusangulate except at the porrect, sharply triangular-acute apex, those at and above midrachis 20-40 x 9-18 mm, 2.1-2.7 times as long as wide; venation of 2(-3) primary nerves from pulvinule, the shallowly sigmoid, faintly pinnate midrib and a weaker posterior nerve produced well above midblade, the secondary venules brochidodrome well within the plane margin, a faint tertiary venulation sometimes externally visible, the whole venation immersed or almost so on upper side, feebly prominulous beneath. Peduncles solitary or geminate, stout, 1.5-4 cm, some subtended by a rudimentary nectariferous lf-stk, capitula 3—15- fld, the pitted subglobose receptacle 1.8-4.5 mm diam; bracts dimorphic, one or two outer ones deltate deflexed and charged ventrally with low-convex homy fuscous nectary, persistent into fruit, the rest oblanceolate 1.5-2.5 mm caducous; pedicels 0-1.5 mm, to 1.5 mm diam; perianth 5-merous; calyx firm, brown when dry and only obscurely nerved, deeply campanulate 8-12 x 3-4.5 mm, minutely sordid-puberulent overall, the teeth unequal, the sinuses between them 1-3.5 mm deep; corolla tubular, slightly dilated upward, (21-)24-30 mm, when fresh pale yellowish green, densely strigulose externally, the almost erect, lanceolate or nearly ovate lobes 4-6 mm; androecium white, 160-214-merous, 48-55 mm, the stemonozone 3-4 mm, the tube 22-28 mm; style to 2-3 mm longer than longer stamens, the stigma not or scarcely dilated 0.2-0.3 mm diam. Pods (few seen) broad-linear nearly straight, 18-20 x 3-3.4 cm, contracted at base into a stout stipe 7-9 mm, abruptly obtuse but mucronulate at very apex, ±18-seeded, the dull-brown coriaceous valves framed by sutures ±2 mm wide, weakly venulose, plane except where low- colliculate over maturing ovules, not seen fully ripe; the dehiscence and seeds unknown.

Distribution and Ecology - In igapó woodland below 250 m, known at present from upper Río Vaupés in long. 70°00'-70°45'W, Com. Vaupés, Colombia; from a creek affluent to Río Guainfa near Limoncito (±2°40'N, 67° SO'W) near San Carlos, and at mouth of Río Casiquiare in SW T. F. Amazonas, Venezuela; and from Río Preto, affluent of Río Negro at ±64°W in Amazonas, Brazil. — Map 49. — Fl. VI-IX(-?).

Local Names and Uses - Arepillo, guamo del río.

Discussion

Macrosamanea consanguinea was described from specimens in bud, and its status, other than a close relationship to M. spruceana, has remained questionable. Four collections from Mitú, on the upper Vaupés in Colombia, in foliage closely comparable with the type but bearing mature flowers and almost ripe fruits, confirm the tentative diagnosis by Cowan. The species now appears to differ from M. spruceana in proportionately wider leaflets, materially shorter calyx and corolla, and an androecium of twice as many filaments. Fruits of Macrosamanea are variable in both length and width, and distinctions at this level are precarious; nevertheless one example of fruiting M. consanguinea (Zarucchi 2188, MO, US) has a pod much narrower than anything yet seen in M. spruceana, and this may provide a further diagnostic character. The difference in color of the flowers’ indumentum mentioned in the protologue is seemingly due to immaturity rather than to any inherent quality of the hairs.

In one flower bud of the type collection there are three ovaries and in a flower of Aymard 9078 (NY) there are two.

Common Names

Arepillo, guamo del río

Distribution

Vaupés Colombia South America| Amazonas Venezuela South America| Amazonas Brazil South America|