Senna lourteigiana

  • Title

    Senna lourteigiana

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna lourteigiana H.S.Irwin & Barneby

  • Description

    35.  Senna lourteigiana Irwin & Barneby, sp. nov., S. undulatam foliolis mediocribus basi utrinque cuneatis necnon androecii forma simulans sed ab ea inflorescentia praeter sepala minutim ciliolata glaberrima, floribus majoribus simulque minus numerosis bractea minuta caduca suffultis, et praesertim legumine secus utramque suturam longitrorsus 2-alato ideoque argute quandrangulo, valvulis papilloso-asperatis nec alte ven- ulosis insigniter diversa.—FRENCH GUIANA: foret dense sur pente, 300 m, sources de la Mana, versant n. des Monts Galbao a 10 km WSW de Saiil, 12.V. 1973 (fr), J. J. de Granville 7657.—Holotypus, NY; isotypus, P!—Saiil, sur le trace Belvedere, 8.III. 1972 (fl), Olde- man B.4339.—Paratypi (fl), CAY, NY.

    Lianas with trunk to 5 cm diam and weak sarmentose treelets of forest understory with dark green or grayish bark and yellow wood, the annotinous branchlets slender terete pliant, remotely livid-punctate, glabrous throughout except for thinly strigulose ovary and (sometimes) residual minute puberulence of lf-stalk, the thin-textured foliage bicolored, glossy dark green above, paler dull beneath, the laxly few-fld racemes borne few together on short weak, functionally leafless branchlets axillary to living lvs, not or scarcely exserted.

    Stipules (caducous, little known), herbaceous, falcately oblanceolate or linear- oblanceolate acute 4-13 x 0.8-3.5 mm, when relatively wide strongly reticulate- nerved.

    Lvs 9-19 cm; petiole including scarcely dilated, often twisted pulvinus variable in length, of 4-foliolate lvs 2-4 cm, of some upper 2-foliolate ones up to 7 cm, at middle 0.8-1.6 mm diam, thence upwardly dilated to the pulvinules, dorsally rounded or bluntly carinate, broadly applanate-sulcate ventrally, in section lunate; glands of 4-foliolate lvs 1 between each pair, shortly stipitate or subsessile, including stipe up to 1.5-2.5 mm long, the body ovoid-ellipsoid or narrowly fusiform glabrous; gland of lower pair sometimes persisting even when the lfts themselves lack; rachis (of 4-foliolate lvs) 1-3.2 cm, a little shorter than petiole; pulvinules 2-3 mm, strongly wrinkled when dry; distal (or only) pair of lfts sub-symmetrically broadly elliptic-acuminate 5.5-11.5 x 2.5-5 cm, the acumen re- tuse, the margin revolute and sometimes undulate, the blade at base almost symmetrically cuneate-decurrent on pulvinule, the straight midrib depressed- canaliculate ventrally, strongly prominent dorsally, the 7-11 pairs of major camptodrome secondary with tertiary and subsequent close reticular venulation all sharply finely prominulous on both faces.

    Racemes loosely shortly 3-7-fld, the axis including peduncle 2-4.5 cm; bracts (caducous, poorly known) ovate-elliptic cymbiform 2-2.5 mm; pedicels 3-3.6 cm; buds plumply ovoid obtuse glabrous; sepals firm subpetaloid yellow, the inner broadly obovate obtuse 13-15 mm, the outer ±1/3 shorter, all becoming papery and prominently venulose; petals (of ser. Bacillares) yellow, glabrous dorsally, the longer up to 27(-31) mm; androecium glabrous, the filaments 1.5-2.5 mm; anthers of 4 median stamens ±9 mm, very slightly incurved, truncate, with divaricate biporose beak ±0.5 mm, of 3 abaxial ones much smaller, 2.5-3 mm, contracted into an erect beak ±1.5 mm; ovary thinly strigulose; style short, the stigmatic orifice 0.5-0.6 mm diam; ovules 108-132.

    Pod (1 seen) pendulous, the stout stipe ±3 mm, the straight body 14.5 x 1.1 cm, abruptly contracted at both ends, quandrangular by production of stiffly coriaceous free wings ±2 mm wide from the length of both sutures, the epidermis of valves brown, densely coarsely papillate; seeds (not seen fully ripe) biseriate, turned broadside to the septa, clothed in thin black pulp, ±5 mm long, angulately ellipsoid-semiobovoid, the testa brown, dullish.—Collections: 22.—Fig. 17.

    Montane and lowland, virgin and secondary forest, sometimes on laterite, 10-700 m, known only from French Guiana, especially from the hill country drained by the sources of the Oyapock, Approuague and western affluents of the Maroni river, but occasional also on or near the outer margin of the coastal plain between Kourou and Kaw, to be expected on the Brazilian slope of Sa. Tumucumaque in adjoining Amapa.—Fl. I-IV.

    The very distinct S. lourteigiana was among the first species of ser. Bacillares to be discovered (cf. specimens in the Candolle and Willdenow herbaria at B, G), and has gone undescribed until now only because mistaken either for Chamaecrista apoucouita (which has, of course, cupshaped, not claviform petiolar glands) or for S. georgica, rather similar in foliage but entirely different in flower and pod. The individual flower of S. lourteigiana outwardly resembles that of S. georgica in the ample sepals, but has three adaxial stamens notably shorter, not much longer, than the four median ones; and its pod is relatively short and quadrangular, not compressed and narrowly ribbonlike, accommodating the seeds in two rows, not in one. Our diagnosis somewhat arbitrarily compares S. lourteigiana with S. undulata, not unlike it in general aspect of the foliage and in the presence of a gland between each pair of leaflets. However the enlarged petaloid bracts, smaller flowers, and coarsely venulose cylindric pod of S. undulata are markedly different.

    We take special pleasure in dedicating to Dr. Alicia Lourteig this handsome senna, which is endemic, so far as known, to French territory. Dr. Lourteig’s knowledge of the history and botanical resources of the Museum d’Histoire Na- turelle in Paris is unrivalled, and her generosity in sharing her knowledge with visitors from America is proverbial.