Senna latifolia

  • Title

    Senna latifolia

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna latifolia (G.Mey.) H.S.Irwin & Barneby

  • Description

    20.  Senna latifolia (G. F. W. Meyer) Irwin & Barneby, comb. nov. Cassia latifolia G. F. W. Meyer, Prim. Fl. Essequeb. 166. 1818.—. . ad originem rivi Arowabischikreek Octobre florentem legi."—Holotypus, consisting of sterile stem with stipules + a detached lf, GOETT!—Chamaefistula latifolia (G. F. W. Meyer) Pittier, 3rd Confer. Interamer. Agric. Caracas (Cat. Pl. Venezol.) 371. 1945.

    Cassia sclerocarpa Vogel, Syn. Gen. Cass. 15. 1837.—"C. bacillaris W[illdenow.] Hrb. 7930. Habt. In Brasilia: Sieber leg. pr. Bahia."—Holotypus, B (hb. Willd. 7930)! = F Neg. 1744! an accompanying ticket gives the locality as Surinam and Bahia, the former being the probable true source.

    Cassia hoffmannseggii Martius ex Bentham in Martius, Fl. Bras. 15(2): 104, majori pro parte. 1870.—"Habitat typus [i.e. var. typica] in provinciae Paraensis sylvis prope Para: Martius; ad flumen Amazonum infra Obidos: Spruce n. 1110 . . .; in provincia do Alto Amazonas ad ostium fluvii Rio Negro: Spruce n. 1558; in provincia Goyaz [really Para, near 2°30'S] ad flumen Tocantins inter S. Joao et Santa Anna: Burchell. . . . etiam . . . e Tarapoto in Peru via: Matthews [sic] n. 1589."—Lectoholotypus, Martius s.n. ‘in sylvis ad Para, provinciae Paraensis. Maio 1820. Vid. Bentham,’ M! isotypi, K! = IPA Neg. 927 = NY Neg. 1446, M (3 sheets) = F Neg. 6238.—Paratypi, Burchell 9342, K! Mathews 1589, K!, but Spruce 1110 and 1558 (K) are C. bacillaris var. benthamiana.

    Cassia latifolia falcistipula Ducke, Archiv. Jard. Bot. Rio de Jan. 3: 112. 1922, statu inter formam et varietatem ambiguo.—"Belem do Para n. 17.031, Gurupa n. 16167; vue a Obidos."— Lectotypus, Ducke 17031, R! isotypi, NY (fragm), US!

    Cassia ornata Bernhardi ex Bentham, Trans. Linn. Soc. London 27: 522. 1871, pro syn.—"Pl. Kappl[erianae] Surin[amenses] exs. n. 1408."—Spm. authent., Kappler 1408, W = F Neg. 32079!

    Bush-ropes highly variable in habit and stature, in capoeira and savanna flowering precociously as weak subshrubs or strong, several-stemmed shrubs (0.5-)2-5 m but occasionally becoming free-standing treelets to 7 m, in older secondary woodland, low forest, or on brushy river-banks becoming sarmentose or scandent and exceptionally to 15 m, the subterete striate or commonly 5-angulate hornotinous stems and the lf-stalks varying from glabrous to densely minutely puberulent or pilosulous with straight appressed, spreading-incurved, or straight spreading hairs up to 0.1-0.25 mm, the chartaceous bicolored lfts above lustrous olivaceous or brownish-olivaceous, beneath duller and paler, either glabrous or thinly puberulent beneath or on both faces, the inflorescence either shortly subcorymbose and immersed in foliage or elongately thyrsiform and leafy-bracteate at base becoming far exserted, its axes always pubescent but the firm globose fl-buds either dull and puberulent or glabrate and waxily lustrous.

    Stipules highly variable in length and amplitude 5-32 x 1-27 mm, either foliaceous ovate-suborbicular obtuse, or obliquely to falcately oblanceolate subacute or obtuse, or (rarely) setiform-subulate, in any case deciduous before the lf, when foliaceous pinnately veined like the lfts.

    Lvs (12-) 14-28 cm; petiole including wrinkled pulvinus (3-)3.5-9(-11) cm, at middle 1.2-2.3 mm diam, widely very shallowly grooved ventrally; rachis (1.5-)2-5.5(-6.5) cm, usually a little shorter, rarely as long as petiole; glands sessile, narrowly or plumply ovoid or dorsoventally compressed-ovoid obtuse (1.5-)2-5(-6) mm tall, one always at or just above first pair of pulvinules, sometimes a smaller one at the distal pair; pulvinules 3.5-7.5(-9) mm; distal pair of lfts asymmetrically ovate, ovate-elliptic or obovate, shortly bluntly (sometimes only obscurely) acuminate, (8.5-)10-17 x (4.5-)5-9.5(-10) a little less to a little more than twice longer than wide, asymmetric at base varying from broadly cuneate to rounded or shallowly cordate, the margin at first minutely revolute, usually plane and sharp-edged at maturity of blade, the gently incurved midrib impressed or shallowly depressed above, carinate beneath, giving rise on each side to (7-)8-12(-13) major camptodrome with ± as many intercalary secondary veins, these with tertiary and subsequent venulation prominulous on both faces, the secondaries more so beneath than above but the reticulation often more so above than beneath, the ultimate, sharply defined areoles either > or <1 mm diam, the proximal pair of lfts similar but ±2/3 as long and often proportionately broader.

    Peduncles stout, together with often abruptly tapering raceme-axis (1.5-)2-8(-9) cm; racemes (3-)5-13(-21)-fld; bracts ovate-acute or lanceolate short-acuminate, cymbiform 1.5-4(-5) mm, firm becoming brown dry, deciduous by anthesis; pedicels 14-40 mm; buds globose, the orbicular outer sepals imbricately enveloping the rest of the perianth until just before expansion, all yellow, fuscous-olivaceous, or reddish, the 2 outer (8-) 10- 17(-21) mm, the 3 inner suborbicular to broadly obovate becoming as long or a little longer; petals deep yellow or orange-yellow, glabrous or dorsally puberulent along the elevated veins, 1 adaxial broadly obovate-flabellate obtuse or emarginate 24-32 mm, the rest similar but commonly less broad, up to 20-30 mm; filaments glabrous or rarely puberulent, those of 4(-5) median stamens 0.9-2.6(-3) mm, those of 3 abaxial ones 2-5.5 mm, the thecae of median ones (6-)6.5-11 mm with divaricate beak 0.4-0.8 mm, of abaxial ones slightly shorter, 4.5-7 mm, but with longer erect or porrect beak 1.4-2.2 mm; ovary glabrous or less commonly strigulose-sericeous; style 2-3 mm, at apex coarsely dilated behind the very oblique stigma and there 1.4-2 mm diam, the orifice of stigma ciliolate (0.4-)0.45-0.9(-l) mm diam; ovules (120-)124-218(-244).

    Pod pendulous stipitate, the short stout stipe 4-8 mm, the cylindric body 24-31 x 1.1-1.3 cm, cuneately contracted at both ends, at apex into the persistent style, the valves becoming stiffly coriaceous, dark brown, coarsely transversely venulose; dehiscence follicular, through the ventral suture; seeds (little known) biseriate, turned broadside to the septa, contained in thin black pulp, obliquely compressed-ellipsoid 7-8 x 3-3.5 mm, the dark brown testa highly lustrous exareolate.—Collections: 126.

    Savanna thickets and both virgin and disturbed forest, either on terra firme or seasonally flooded river banks, on a variety of sand and clay soils, mostly below 700 but in inter-Andean valleys up to 1400 m, interruptedly widespread over much of the Amazon Basin, the Guianas and the e. periphery of Guayana Highland: s.-e. Venezuela (Caroni-Orinoco slope in Amazonas and Delta-Amacuro); coastal plain and interior uplands of Guyana, Surinam and French Guiana; valleys of the Amazon and tributaries upstream from the delta to Terr, do Roraima, extreme s.-e. Colombia (Cerro Mitu on upper Rio Vaupes), e.-centr. Peru (Loreto, San Martin, Huanuco, e. Ayacucho and Cuzco, on Rio Apurimac reaching s. to 12°30' and on Rio Urubamba to 13° lat.) following Rios Purus and Jurua into Terr, do Acre, Brazil and (perhaps isolated) on Rio Beni near 15°25'S in n.-e. Bolivia (La Paz) but apparently otherwise absent from the basins of Rios Madeira, Tapajos and Xingu, s. on Rio Tocantins into extreme n. Goias (near 7°20'S) and adjoining Maranhao.—Fl. (I-)II-VII, fr. VI onward, the ripe and opened pods long persistent.—Brusquillo (Venezuela).

    Firm glossy reticulate leaflets, inequilateral at base and plane-margined, coinciding with enlarged outer petaloid sepals that enclose the flower until shortly before anthesis characterize this handsome and widely dispersed Hylaean senna. The tough-walled, coarsely venose pod resembles that of compatriot S. quinquangulata, but this, more evidently different in its smaller flower and herbaceous sepals that separate long before true anthesis, differs in the hornlike or slenderly claviform (not sessile ovoid obtuse) petiolar glands constantly present between both pairs of leaflets. In its ample calyx S. latifolia resembles S. tapajozensis, but this is readily distinguished by having three abaxial stamens longer, not shorter, than the four median ones.

    Senna latifolia varies considerably in length and dispersal of hairs on stem, leaflet and calyx, and conspicuously in development of the stipules which, although commonly (and typically) foliaceous, can dwindle in outline to narrowly falcate or even subulate-setaceous. An exceptionally pubescent form encountered on the Jurua river (Prance 13018) represents an extreme in this direction. The form with narrow falciform stipules described by Ducke from the Amazon delta region is not confined there, but has been collected also in Peru (Schunke 1867) and in Guyana (A. C. Smith 2159). In lower Amazonia narrow stipules are often associated with a second petiolar gland, between the distal pair of leaflets, such as occurs only very rarely elsewhere in the species. But the variation noted occurs in random combinations without geographic correlation.

    It may come as a surprise to find the name Cassia hoffmannseggii listed in the synonymy of S. latifolia. While Bentham at first classed C. hoffmannseggii among his Speciosae or Bacillares with strongly heteromorphic stamens, it was only the var. gardnerana (=our S. georgica) that had this type of androecium, the material of typical C. hoffmannseggii cited in the protologue representing either the narrow-stipulate form of S. latifolia or S. bacillaris var. benthamiana. For greater detail see our account of 46. S. georgica (p. 193).