Senna villosa

  • Title

    Senna villosa

  • Author(s)

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna villosa (Mill.) H.S.Irwin & Barneby

  • Description

    146.  Senna villosa (P. Miller) Irwin & Barneby, comb. nov. Cassia villosa P. Miller, Gard. Diet. ed. 8, Cassia no. 4. 1768.—"Senna spuria arborea villosa . . . siliquis articulatis. Houst[on] MSS . . . sent me from Cam- peachy by the late Dr. Houston . . ."—Holotypus, collected in Campeche in 1730, ticketed successively by Houston and by Miller, BM! = BH Neg. 5166 = NY Neg. 162.—Desmodiocassia villosa (P. Miller) Britton & Rose, N. Amer. Fl. 23(4): 244. 1930.

    Cassia astroites Chamisso & Schlechtendal, Linnaea 5: 597. 1830.—"H[erb.] W[illd.] no. 7963 (specimen, e Willd., Humboldtianum. Amer. merid. [but certainly Mexican and, not noticed by Kunth, probably not from Humboldt]) . . . Plan del rio [Veracruz, Schiede & Deppe 702]."—Lectoholotypus, WILLD-7963, B! No paratypi (Schiede & Deppe 702) found.— Chamaefistula astroites (Chamisso & Schlechtendal) G. Don, Gen. Hist. Diehl. Pl. 2: 451. 1832.—Correctly equated with C. villosa by Bentham, 1871.

    Cassia geniculata G. Don, Gen. Hist. Diehl. PI. 2: 440. 1832.—"Native of Peru (v.s. in herb. Lamb[ert].)."—Presumed holotypus, labelled ‘Peru’ by Pavon but certainly Mexican and collected probably by Sesse or associates, BM! = NY Neg. 167; isotypus, G!—Correctly equated with C. villosa by Bentham, 1871.

    Cassia geniculata Sesse & Mocino, Pl. Nov. Hisp. 60. 1894.—"Habitat Metepec [not located by McVaugh, 1977, p. 169; the places of this name in Hidalgo, Puebla and Mexico are all in tierra templada and thus improbable type-localities]."—Holotypus, sub nom. ined. "Cassia armillaris Sesse," MA (hb. S. & M. 1134, 1162)! both probably isotypi of the preceding.

    Cassia articulata Rose, Contrib. U.S. Nat. Herb. 12: 266. 1909.—"Collected by C. A. Purpus at San Pablo, near San Jose del Cabo, Lower California in 1901 (no. 287, type) and by Nelson and Goldman between Miraflores and San Bernardino [properly Bernardo] ranch in Sierra La Laguna . . . January, 1906 (no. 7419)."—Holotypus, US (no. 470361)! paratypi (Nelson & Goldman 7418), NY, US!—Correctly equated with C. villosa by Standley, 1922, p. 406.

    Cassia stellata M. E. Jones, Extracts from Contrib. W. Bot. 18: 40. 1933.—"No. 27196, Ca- cachilla mts, L[ower] California], Oct. 2, 1930 and at Triunfo, No. 27200, Oct. 7."—Lectoholotypus (Morton, Contrib. U.S. Nat. Herb. 29(3): 100. 1945): Jones 27196, POM (no. 191866)! isotypus, NY! paratypus, Jones 27200, US!—Correctly equated by Morton, l.c., with C. villosa.

    Cassia astroites sensu Vogel, 1837, p. 41.

    Cassia villosa sensu Bentham, Hook. Icon. 11: t. 1060. 1870 & 1871, p. 536.

    Amply leafy, sometimes arborescent shrubs at anthesis 1-4 m, densely scabrous-tomentulose throughout with thick-stalked gray or lutescent stellate hairs in profile 0.2-0.7(-1.1) mm tall, the thick-textured foliage bicolored, dull dark green above, paler beneath, the inflorescence of racemes either all axillary to cauline lvs or some late ones forming a small, shortly exserted subcorymbose panicle.

    Stipules erect, narrowly linear-attenuate or setiform 3.5-6 mm, caducous.

    Lvs 6-17 cm; petiole including swollen but not wrinkled pulvinus 1.5-3.5(-4.3) cm, at middle 0.8-1.8 mm diam, rounded dorsally, shallowly narrow-sulcate ventrally; rachis (1.3-)2.5-8 cm; glands (often eaten) between proximal and sometimes 1-2 next succeeding (but not the distal) pairs of lfts, stipitate or subsessile, in profile 1.3-3 mm tall, the stipe and commonly the head also stellate-pubescent, the latter either slenderly or squatly ovoid, acute or obtuse 0.4-1.2(-1.6) mm diam; pulvinules 1-2.5 mm; lfts (2-)3-5, of most lvs either 3 or 4 pairs, accrescent distally, the distal pair lance- or elliptic-acuminate, ovate-elliptic, ovate-acuminate or obliquely ovate and deltately subacute (2-)2.7-8 x (1.8-) 1.2-2.7 cm, 2.2-3.8 times as long as wide, at oblique base cordate to rounded on proximal and rounded to cuneate on distal side, the margin revolute, the midrib and (5-)6-9(-10) pairs of incurved-ascending camptodrome secondary nerves immersed above, finely prominent beneath, the tertiary venulation imperceptible.

    Peduncles 1-3.5(-5) cm; racemes densely 5-25-fld, the axis somewhat elongating, becoming 3-30 mm; bracts subulate-filiform 2-5 mm caducous; pedicels slender 6-13 mm; fl-buds oblong-ellipsoid obtuse, nodding when young; sepals submembranous, densely stellate dorsally except where interior in vernation, of nearly equal length, elliptic-oblong 5-8 mm; petals pale yellow fading whitish brown-veined, glabrous dorsally, subhomomorphic except the 2 abaxial a trifle longer, all obovate-cuneate obtuse or subemarginate, the longest 7.5-10 x 4-6 mm; androecium glabrous or the filaments remotely stellate, functionally 7-merous, the filaments alternately a little longer (oppositisepalous) and shorter 1.6-2.7 mm, the linear-lanceolate anthers brown when dry, not much differentiated, those of 4 median stamens nearly straight 3.1-4 mm truncate, those of 3 abaxial ones a trifle longer, 3.8-5 mm, and more incurved, constricted 0.2-0.4 mm below the somewhat oblique 1-pored orifice; ovary densely stellate-tomentulose; style glabrous, gently incurved 2-2.5 mm, at attenuate apex ±0.2 mm diam; ovules (8-)10-18.

    Pod obliquely pendulous, the stipe 2-4 mm, the body in profile undulately moniliform 6-10 x 0.4-0.55 cm, laterally compressed, slenderly carinate by the sutures, constricted between the seeds, the isthmi 1.5-4 mm wide, the seed-locules 5-8 mm long, when ripe separated in the form of achenes, the firmly papery green, brunnescent valves densely stellate, elevated over each seed as a narrow ridge oriented lengthwise to the pod; seeds basipetally vertical to the long axis of pod, obovoid compressed parallel to valves, 3.7-4.5 x 2.6-3.1 mm, the testa fawn- or chocolate-brown smooth but not or scarcely lustrous, crackled, the subcentric areole oval (0.7-)0.8-1.5 x (0.5-)0.6-l mm.—Collections: 44.— Fig. 9 (petiolar nectary), 14 (pod, seed).

    Scrub thickets and brushy canyon slopes, 10-1600(-1860) m, in continental Mexico (and presumably Bahamas) often calciphile, local, s.-e. Mexico from centr. Veracruz to Yucatan, the headwaters of Rio Grande in Chiapas, s.-e. and centr. Oaxaca, and Puebla, in the two latter states entering the Pacific drainage; remotely disjunct in the foothills of the Cape mountains in s. peninsular Baja California; and (perhaps naturalized) on New Providence I. in the Bahamas.— Fl. in continental Mexico VIII-I; on the Cape V-X.

    The singular stellate hairs which clothe the stems, foliage, inflorescence and pod of S. villosa are composed of a thickened, often yellowish or rufescent stalk bearing on its summit a tuft of fine radiating and ascending whitish filaments. The whole trichome suggests a diminutive sea anemone and is unique in Senna to this one species.

    The populations of S. villosa on the Cape mountains of Baja California differ from those of continental Mexico in the less obviously acuminate leaflets and somewhat less pronounced constriction of the pod valves between seeds, the isthmi being 3-4 (not 1.5-3) mm wide. These slight differences, expectable in the circumstances, are insufficient for taxonomic recognition.