Senna

Taxonomy

Senna P. Miller Gard. Dict. Abr. ed. 4. 28 Jan 1754.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.2.17.
Tribe: Cassieae.
Subtribe: Cassiinae.
Species Studied - Species in Genus: 86 studied; ca. 260 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 3–49 cm long; 0.4–3.3 cm wide; 0.2–1.5 cm thick; 2–9 times longer than wide to more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; curved, or S-curved, or straight; not plicate; not twisted; asymmetrical; linear to oblong; not inflated; compressed, or terete, or quadrangular; without beak; long tapered at apex to tapered at apex; aligned with longitudinal axis of fruit; tapered at base to short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous to ligneous; seed chambers externally invisible, or visible (occasionally umbonate); margin constricted, or not constricted; margin slightly constricted along both margins; margin without sulcus; margin embellished; margin with wing(s); wing(s) occasionally present, or absent; wing(s) 2 (or more?); wing(s) 0.1–10 mm wide; wing(s) valvular; wing(s) on both valves; stipitate to substipitate; with the stipe 6–20 mm long; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves along 1 suture, or both sutures; active, or passive; with valves twisting. Replum invisible. Epicarp dull to glossy; monochrome; reddish or purplish brown, or black, or green, or tan; with surface texture uniform; glabrous to pubescent and indurate (with short to long); with hairs erect; eglandular; without spines; smooth, or not smooth; with elevated features, or recessed features; veined, or not veined; longitudinally veined relative to fruit length, or transversely veined relative to fruit length, or reticulately veined; not tuberculate; striate, or lenticular, or subvesicular, or dotted, or glandular dotted, or rugose, or verrucose-rugose, or tuberculate, or warty, or blistered, or papillose, or pusticulate, or scurfy, or shagreen, or scaly, or ribbed (reticulate, rugose, smooth, transversely veined, shagreen, resinously black-dotted or with margins regularly transversely cracked and valve faces entire in S. emarginata); glandularly punctate, or pitted, or punctate; not exfoliating; with cracks; cracking transverse to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present, or absent; surface not veined; 1-layered (?); without balsamic vesicles; without fibers; without reniform canals; spongy, or solid; ligneous to coriaceous. Endocarp present; visible; glossy; opaque; monochrome; brown, or black; spongy (? stated as "pulpy" when fresh); without adhering pieces of testa; septate to nonseptate (ligneous to chartaceous; S. bicapsularis has a longitudinal septum dividing fruit in half with seeds on alternate sides and the usual transverse septa); not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 10–60; length parallel with fruit length to transverse to fruit length; neither overlapping nor touching; in 1 series, or 2 or more series. Funiculus 0.1–4 mm long; of 1 length only; filiform to thick; straight, or contorted, or S-curved, or curved, or hooked, or plicate, or triangular (straight, straight and 1-plicate near apex or base, S-curved, or contorted). Aril absent.

Seed: 2.5–10 mm long; 1.3–7 mm wide; 1–3 mm thick; not overgrown; angular, or not angular; symmetrical, or asymmetrical; linear, or lanceolate, or elliptic, or ovate, or circular, or oblong, or cordate, or triangular, or quadrangular, or rectangular, or D-shaped, or reniform, or irregular, or C-shaped, or trapezoid, or rhombic, or pyriform (D-shaped, linear, ovate, rhombic, subcircular, triangular); compressed, or flattened, or terete (occasionally); with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; glossy to dull; not modified by a bloom; colored; monochrome (?); black, or brown, or tan, or ivory, or green, or olive, or white, or yellow, or red (various shades of brown, pink, black, greenish, purplish, grayish, or ivory); glabrous; smooth, or not smooth; with elevated features, or recessed features; smooth to faintly rugose, or pustulate; occasionally cuticle silvery to minutely pitted with small separate pits, or striate; osseous. Pleurogram present (with large or small areola similar to dissimilar in color and texture from testa), or absent; 100 %. Pseudopleurogram absent. Fracture lines present (transverse ones more prominent or restricted to areolas); reticulate (?). Rim absent. Wing(s) absent. Raphe visible, or not visible. Hilum present; visible, or fully concealed; concealed by funicular remnant; without faboid split; punctiform, or larger than punctiform; 0.1–0.3 mm long; with curved outline; circular; subapical to radicle tip (often within collar of testa); flush, or recessed; not within corona, halo, or rim. Lens discernible (often within hilar depression and collar or occasionally within its own depression and collar); 0.1–0.6 mm long; with margins straight, or curved; oblong, or triangular; elliptic; not in groove of raphe; mounded to recessed; same color as testa, or dissimilar color from testa; black to tan; not within corona, halo, or rim. Endosperm present; thick; not pluglike and not resembling tip of radicle; adnate to testa. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin entire 180 degrees from base of radicle; similar at apex; partially concealing radicle; with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Pantropic.

Pantropic New World and Old World; southern United States, Mexico, West Indies, Central America, and South America; Argentina, Peru, Brazil, Ecuador, and the Guianas; Mediterranean, Japan, Africa, Madagascar, Indian Ocean, Southwest Asia, India, Indochina, Indonesia and the Philippines, Australia, Pacific, New Guinea, Fiji, Hawaii, Korea, and China (southern).

Generic Notes

Irwin and Barneby (1982) give a lucid and interesting account of the interrelationship of fruit (pod) types in the genus and the variations in fruit compression. Bravo et al. (1986) used seed-fruit characters in keying species belonging to the series Aphyllae.