Senna chrysocarpa

  • Title

    Senna chrysocarpa

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna chrysocarpa (Desv.) H.S.Irwin & Barneby

  • Description

    36.  Senna chrysocarpa (Desvaux) Irwin & Barneby, comb. nov. Cassia chrysocarpa Desvaux, J. Bot. 3(2): 72. 1814.—"Habitat in Gujana."—Holotypus, P (hb. Desvaux.)! isotypus (fragm), F!—C. chrysotricha Colladon, Hist. Casses 99, nom. illegit., t. 13. 1816.—"Hab. in Guiana. Patris (v.s. sp. in h. DC.)."—Sp. authent.: "Cayenne," G-DC!

    Cassia virgata L. C. Richard, Actes Soc. Hist. Nat. Paris 1: 108. 1792.—. . e Cayenna . . . missarum a domino LeBlond."—Holotypus, LeBlond s.n., P (hb. Richard.)!—Non C. virgata Swartz, 1788.

    Cassia chrysogyne Miquel, Linnaea 18: 581. 1844.—"Crescit prope Paramaribo in sylva juxta viam ad Kwatta, ad Wanicka, m. Sept. [H. G. Focke]."—Holotypus, U, not seen; isotypus, labelled ‘Surinam. Focke [misit] Miquel,’ K (hb. Benth.)! = NY Neg. 1443.—Equated with C. chrysocarpa by Bentham, 1871, p. 523.

    Weakly woody shrubs and bush-ropes, in open places or on newly cleared land diffusely ascending, becoming sarmentose in older capoeira and at forest margins, the terminal flowering branchlets then often semi-pendulous from the canopy, at anthesis 2-10 m, the stems prominently angulate, variably pilosulous or strigulose almost throughout with appressed, antrorsely or retrorsely incurved, sometimes suberect hairs up to 0. l-0.3(-0.4) mm, the foliage strongly bicolored, the lft- blades sublustrously dark- or brownish-olivaceous above, paler dull beneath, usually pubescent on both faces but sometimes glabrous except along major veins, the gray- or yellow-pubescent inflorescence often elongately narrow-thyrsiform-paniculate, the lower racemes leafy-bracteate, the upper commonly leafless or subtended by degenerate leafless petioles.

    Stipules narrowly setiform incurved 3-8 mm, at base 0.15-0.4 mm wide, early dry and caducous.

    Larger lvs 3-8 cm; petiole including discolored, little swollen pulvinus 1-2.5(-3) cm, at middle 0.5-1.1(-1.3) mm diam, openly grooved ventrally, the wings a trifle dilated distally below the first pair of pulvinules; rachis 4-9(-11) mm, shorter than petiole; gland ascending from slightly above first pair, slenderly lance-ellipsoid acute or obtuse 0.5-1 mm diam, short-stipitate or sessile, glabrous or rarely hispidulous, in profile (2-)2.4-3.8 mm tall; pulvinules variably swollen (1-) 1.3—2.7 mm; distal pair of lfts sharply divaricate from lf-stalk, very obliquely ovate-obovate or ovate-elliptic, broadly obtuse to broadly deltate-acute 23-60 x 12-32 mm, ±2-1.3 times as long as wide, at base cordate on proximal and rounded to cuneate on distal side, the margin revolute, the ± excentric, almost always incurved midrib and 5-8(-9) pairs of camptodrome secondary veins finely prominulous on upper and sharply so on lower face, the rare intercalary secondary and tertiary venulation faint, further reticulation yet fainter or obsolete.

    Peduncles with raceme-axis stiffly incurved-ascending, proximally stout but tapering distally, mostly (1-) 1.5-5.5 cm, the racemes (2-)3-9(-12)-fld, when young or when few-fld subumbellate; bracts ovate or lanceolate acute or acuminulate 1.5-3.5(-4) x 1-2.4 mm, at base not or only narrowly embracing base of pedicel, deciduous before or very soon after anthesis; pedicels (9-)12-20(-24) mm, early thickened except at very base; buds subglobose, subappressed-pilosulous, rarely glabrescent; sepals yellowish or sometimes red-lineolate, the inner subpetaloid, strongly graduated, the smallest outermost V2-V3 the largest innermost, all ovate-, obovate-orbicular or broadly oblong-obovate very obtuse, faintly veined, the longest 8.5-11.5 mm; petals yellow or orange-yellow, puberulent dorsally, 3 adaxial broadly obovate- or flabellate-cuneate up to 13-18(-21) mm, the 2 abaxial longer and narrower, up to (15-) 17-29 mm, one of them oblique and incurved around 2 longer stamens; filaments glabrous, those of 4 median stamens 1.5-2.6 mm, those of 3 abaxial ones 2.2-5 mm; anthers glabrous or exceptionally very sparsely puberulent, those of median stamens 4.5-6 mm, with introrsely 2-porose beak 0.2-0.4 mm, those of abaxial ones no longer and usually a trifle smaller, 3.5-5 mm with porrect 2-porose beak 0.5-0.9 mm; ovary densely yellowish-pilosulous; style glabrescent 2-2.7(-3) mm, at apex gently incurved and 0.35-0.6 mm diam, the stigmatic orifice 0.2-0.3 mm diam; ovules 76-108.

    Pod stiffly spreading-ascending, stoutly short-stipitate, the stipe 3.5-7 mm, the narrowly cylindroid body 4-9.5 x 0.7-0.95 cm, abruptly contracted at each end, usually a little decurved, the valves becoming papery blackish lustrous, thinly pilosulous, apparently indehiscent, the seeds released only by rotting of the fruit; seeds biseriate, turned broadside to the septa, embedded in fetid pulp (black when dry), compressed-obovoid 4.1-4.6 mm, the testa brilliantly glossy-castaneous, a faintly differentiated areole ±3.5-3.8 x 2.3-2.7 mm on each face equally glossy or slightly roughened.—Collections: 72.

    Open forest, riverine forest and thickets of sand-savanna, both on varzea and terra firme, becoming locally abundant in capoeira and along highways, mostly, perhaps always, below 300 m, common on the coastal plain and interior lowlands of Guyana (Courantyne valley), French Guiana, Surinam, and n.-e. Brazil (Amapa, Para and Maranhao), ascending the Amazon and Rio Branco w., in e. Amazonas and Terr, do Roraima, to ±61°W, and s. on Rio Araguaia into extreme n.-w. Mato Grosso.—Fl. (VI-)VII-XII(-III).

    In its area of dispersal S. chrysocarpa is readily recognized by a combination of relatively small leaflets, a solitary petiolar gland, a narrow thyrsiform panicle of subumbellate racemes, and short indehiscent pulpy pods spreading-ascending on stiffened pedicels. It is closely related to the somewhat smaller-flowered, almost isandrous S. insularis endemic to Cuba and to S. rizzinii, which replaces it in Brazil east- and southward from Ceara; when better known these three may well emerge as no more than geographic expressions of one polymorphic species.  For the present S. rizzinii appears somewhat precariously distinct in its less angulate stems, larger floral bracts, longer style and fewer (±44-58, not 76-108) ovules, characters that need confirmation from more numerous specimens than are now available.

    The earliest known example of S. chrysocarpa is in Aublet s herbarium (BM!) preserved under an unpublished name ("Cassia aulica" = MO Neg. 2274). Another, without locality "donne par M. Dupuis," has lain for more than 200 years unidentified in the Lamarckian herbarium (P).