Dicymbe mollis Barneby

Authority

Barneby, Rupert C. 1990. Three new caesalpiniaceous trees from Guayana and its periphery. Mem. New York Bot. Gard. 64: 202-209.

Family

Caesalpiniaceae

Scientific Name

Dicymbe mollis Barneby

Description

Species Description - Inter species pentapetalas sectionem Dicymbem sistentes his notulis insignis et facile cognoscenda: foliola 3-4-juga membranacea dorso moUiter pilosa nee cerifera; inflorescentia cymoso-paniculata; bracteolae c u m hypanthio profunde campanulato ultra medium oncretae; petala parva quam sepaUs vix longiora; ovarii dense sericeo-pilosi stipes glaber. Amply foliate trees 6-11 m, the young growth, except for glabrous upper face of leaflets, softly pilosulous with fine golden hairs to ±0.5 mm, the thinly papery-membranaceous olivaceous leaflets thinly so beneath, densely ciliolate, the cymose-paniculate terminal inflorescence densely golden-pubescent throughout. Stipules eariy caducous, not seen. One or two supra-axillary, narrowly ovoid perules 3-4.5 mm composed of striate, dorsally silky ovate scales. Leaf-stalks 1- 17 cm; pulvinules grossly swollen, 4-6.5 m m; leaflets 3-4 pairs, distally accrescent, the blades ovate or oblong-elliptic from broadly rounded base, shortly obtusely acuminate, the distal pair 8-17.5 X 3.8-6.5 cm, 2.1-2.7 times as long as wide; midrib immersed on upper face, cariniform beneath, giving rise to 6-7 major (and some weaker intercalary) secondary veins incurved-ascending to anastomosis well within the plane margin, and ultimately to a fine close reticulum of veinlets prominulous on both faces. Panicle ±7-13 X 4-6 cm, the branches ±10-15-flowered; bracts ovate, nidulating the very young flower-buds but thrown off as the pedicel begins to lengthen; mature pedicels ± 2 cm; hypanthium campanulate, at early anthesis ± 5 x 5 mm, becoming 9 mm; bracteoles adnate to hypanthium for well over half its length, the free blades broadly ovate 12-16 x 9-11 mm , each charged dorsally just below hooded apex with a hemispherical gland ±1.2 mm diam.; flowers with sepals 4, firm, one broadly and 3 narrowly ovate, ±10 X 5-7 mm , all glabrous internally, dorsally silkystrigulose except toward the submembranous margin; petals 5, equiform, elliptic-oblanceolate, as long as or up to 2 mm longer than sepals, all densely sericeous externally, glabrous within; stamens 10, the filaments of outer rank thinly pilosulous at very base, the rest glabrous; anthers 4-5 mm; ovary stipitate, the glabrous stipe 2-3 mm , the body obliquely ascending, densely loosely pilose, the distally glabrous style up to 8 mm . Fruit unknown.

Discussion

Type. BRAZIL. Estado do Amazonas: Rio Tuari, Lago Uirauagu (vernacular Passaro Grande), 0°20'N, 67°20'W [on a branch of Rio Negro shortly downstream from I^ana], 13 N o v 1987 (fl), M . L. Kawasaki 126 (holotype INPA; isotypes K, M O , N Y (2 sheets), US).-Ibid., on same day (in bud), Kawasaki 121 (paratypes F, K, M O , N Y , US).

Tetrasepalous, symmetrically pentapetalous flowers place D. mollis squarely within subgenus and section Dicymbe as defined by Cowan (1957: 338-339), except that the bracteoles are tipped with a sessile hemispherical gland. Such a gland, however, was later discovered in Z). bernardii {Cov/an, 1958: 28; 1961: 75, revised key), and its presence is therefore no obstacle to admitting D. mollis to the section. The foUowing combination of characters separates the species decisively from all described members of sect. Dicymbe: leaflets three or four pairs per leaf, rounded at base, of papery-membranous texture, and on the dorsal face softly pilose but lacking waxy grains; a cymose-paniculate inflorescence bracteoles adnate to the deeply campanulate hypanthium through more than half its length; and petals scarcely or not surpassing the sepals. In the inflorescence and in the gland-tipped sepals it approaches subgen. Apoxypetala Cowan, but must be excluded from this by the five equal and sessile petals. Its strongly adnate bracteoles are matched in sect. Dicymbe only by D. jenmanii Sandw. of upland Guyana, but this has a simply racemose inflorescence of fewer, much larger flowers and the dorsal face of leaflets at once minutely strigulose and waxy-papillate.

Distribution

In campirana near 100 m ; known only from the two collections cited.

Guyana South America|