Senna tenuifolia (Vogel) H.S.Irwin & Barneby

Authors

Howard S. Irwin, Rupert C. Barneby

Authority

Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 1: 1-454.

Family

Caesalpiniaceae

Scientific Name

Senna tenuifolia (Vogel) H.S.Irwin & Barneby

Type

Holotypus, †B = F Neg. 7755; neoholotypus, former isotypus, Sellow s.n., K! = IPA Neg. 894 = NY Neg. 1440; isotypus, FI (hb. Webb.)!

Synonyms

Cassia tenuifolia Vogel

Description

Species Description - Fruticose but of unknown stature and habit, the terete, finely striate, loosely subcorymbosely forking annotinous branchlets whitish-gray, the hornotinous branchlets with foliage and inflorescence yellowish-pilosulous with spreading or incumbent hairs up to 0.35-0.6 mm, the membranous lfts bicolored when dry, brown, thinly pubescent and sublustrous above, paler and densely incurved-pi- losulous beneath, the few-fld racemes axillary to living lvs, immersed or almost so in foliage. Stipules linear-setiform (? 1.5-)3-6 x <0.5 mm, early dry caducous. Lvs 4-13 cm; petiole including scarcely swollen pulvinus l-2.5(-3) cm, at middle 0.4-0.9 mm diam, openly shallow-sulcate; rachis 9-10(-13) mm; gland 1 erect from between proximal pair of lfts, slenderly claviform 1.3-3 x 0.3-0.5 mm glabrous; pulvinules 1-2 mm, little dilated but wrinkled when dry; distal pair of lfts obliquely elliptic obtuse mucronulate or subacute 3-7(-8.5) x 1.5-3(-3.5) cm, at base rounded to broadly cuneate on proximal and cuneate on distal side, the margin re volute, the slender straight or gently incurved midrib with ±6-9(-10) pairs of major secondary veins finely prominulous above, a little more sharply so beneath, the tertiary venulation open and irregular; proximal pair of lfts ±1/2 as large, often proportionately broader. Racemes loosely, at first subcorymbosely 3-5-fld, the axis including short slender peduncle becoming 1-3 cm; bracts ovate 1.5-2 mm, caducous; pedicels 2-2.5 cm; young buds globose, densely pubescent; sepals elliptic-obovate obtuse 7-8.5 mm; petals yellow, pubescent dorsally on and between veins, the blades oblong- obovate, including short claw 18-23 mm, one dorsal emarginate, the rest obtuse; filaments puberulent, those of 4 median stamens 1.5-3 mm, of 3 abaxial ones 3.5-6 mm; anthers puberulent in the grooves, those of 4 median stamens 3-4.5 mm with very short divaricate beak, those of 3 abaxial ones lunately incurved 5-6.5 mm, with porrect beak ±1 mm dehiscent by slits its whole length; ovary densely pilosulous; style little dilated, ±0.7 mm diam just below the ciliolate incurved stigma, the orifice 0.3-0.4 mm diam; ovules 66-94. Pod not known ripe, when ± half formed the stipe ±7 mm, the linear straight body 12 cm, the expanding ovules forming 2 overlapping ranks.—Collections: 17.

Distribution and Ecology - Habitat unknown, to be sought in moist open woodland near 850-1000 m, apparently local in the Atlantic forest of s.-e. Brazil in Rio de Janeiro (Organ Mountains; Parahyba valley) and extreme e. Minas Gerais (Rio Mucuri to Sa. do Caparao), 41°30'-43°W, 18°-22°30'S.—Fl. (?)IV-VI, IX-X.

Discussion

A poorly known, seldom collected senna, resembling in foliage and habit the almost sympatric S. angulata, but differing in the pallid epidermis of the terete young branchlets, the small deciduous bracts, the shorter, densely pubescent sepals, and the generally smaller flower (long petals ± 18-23, not 24-33 mm). The pod, which appears to be relatively thin-textured, may perhaps furnish further differential characters. Although Bentham referred C. tenuifolia to his ser. Bacillares, characterized by stamens of about equal length, the androecium is actually, as described by Vogel in Linnaea, heteromorphic in the style of ser. Speciosae, the three abaxial anthers being both larger and borne on much longer filaments. In this respect it resembles the allopatric S. macranthera var. pudibunda, which appears however safely distinct in its exserted paniculate inflorescence, larger petals and anthers, and short terete pod.

Distribution

Rio de Janeiro Brazil South America| Minas Gerais Brazil South America|