Senna occidentalis (L.) Link

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 occidentalis (L.) Link

Type

lectoholotypus (Brenan, 1967, pl. 78), BM (hb. Cliffort.)! The spm. LINN 528.13, indicated as typus by De Wit, 1955, p. 256 and accepted as such by Symon, 1966, p. 88, was acquired by Linnaeus only in 1758 with the herbarium of P. Browne.—Senna occidental

Synonyms

Cassia occidentalis L., Ditremexa occidentalis (L.) Britton & Rose ex Britton & P.Wilson, Cassia falcata L., Cassia planisiliqua L., Cassia plumieri DC., Cassia caroliniana Walter, Cassia occidentalis var. aristata Collad., Cassia ciliata Raf., Cassia obliquifolia Schrank

Description

Species Description - Coarse, amply leafy foetid herbs from black, yellow-tipped roots, in temperate or seasonally dry climates truly annual, perishing with onset of cold or dry weather, but under warm moist or tropical conditions either monocarpic of indefinite duration or softly fruticose and of 2-3 years duration, finally many-stemmed and bushy, at anthesis (0.5-)1.5-22 (but most often ±4-12) dm, appearing glabrous and the obtusely angled or sulcate stems truly or almost so, the axis of inflorescence thinly strigulose-pilosulous, the thin-textured, when dry dull olivaceous lfts glabrous above, ciliolate with forwardly ascending stiff hairs up to 0.25-0.5 mm, beneath charged with scattered minute thickened trichomes, the inflorescence composed of subsessile or shortly pedunculate few-fld racemes axillary proximally to fully developed lvs, these distally ± abruptly reduced to a rudimentary lf-stalk with undiminished petiolar gland, the uppermost racemes forming a shortly exserted narrow thyrse. Stipules loosely erect, thinly herbaceous often livid-tinged or purple-dotted, broadly triangular- to lance-acuminate (3-)4.5-11(-13) x (1.5-)2-4.5(-5) cm, at oblique base, either on side further from petiole or (when broad) on both sides, rounded and bluntly auriculate-amplexicaul, early dry caducous. Major lvs (except in rare starveling plants) 11-24(-26) cm; petiole with swollen or little differentiated, sometimes discolored pulvinus 2.5-5(-5.5) cm, at middle 0.8-2 mm diam, bluntly 3-costate dorso-laterally, thickly obtusely margined and openly grooved ventrally; gland contiguous to pulvinus sessile or almost so, plumply ovoid, hemispherical, depressed-hemispherical or subglobose, in profile 0.7-1.8 x (0.6-)0.8-2.2 mm, varying from a little longer to a little shorter than diam, always obtuse, when fresh livid-reddish, nigrescent and wrinkled when dry, sometimes a second gland near the first, but none between lfts; rachis (4-)6-14 cm, its subulate or hornlike terminal appendage thickened and livid proximally; pulvinules discolored (1.7-)2-4 mm; lfts (3-)4-6, of most plants exactly 4 or 5 pairs, accrescent distally, the proportionately broad proximal pair much the shortest, the distal pair broadly lance- or ovate- (exceptionally obovate)- acuminate 4.5-9.5(-10) x (1.2-)1.4-3.5(-3.8) cm, (2.1-)2.4-4(-5) times longer than wide, at inequilateral base cordately decurrent on pulvinule on proximal or on both sides, the midrib immersed or scarcely raised above, cariniform beneath, the 9-15 pairs of major camptodrome and random intercalary secondary veins finely prominulous above, more sharply so beneath, the tertiary venulation invisible on both faces or discolored but scarcely raised beneath. Peduncles (l-)1.5-4.5(-7) mm; racemes very shortly or subumbellately (1-)2-5- fid, the axis becoming 0-5 mm, the whole axis including peduncle not over 1 cm; bracts thinly herbaceous early dry brown caducous, lance (oblance)-acuminate (5-)6- 16(- 18) x (0.8-) 1.8-4.5 mm; mature pedicels 8-17(-21) mm; fl-buds nodding glabrous (puberulent at base), plumply obovoid; sepals submembranous pallid or commonly pinkish- or fuscous-tinged, moderately graduated, obovate or oblong-obovate, the outer (5-)5.5-7.5 mm, the longest inner one (6.5-)7-10 mm; petals glabrous, yellow drying whitish brown-veined, the vexillar one usually obcordate, the 2 lateral ones obovate, the 2 abaxial ones oblanceolate, all of equal length or either the anterior or posterior ones longer, the longest petal 12-16(-17) mm; androecium glabrous, the 3 staminodes 0.7-1.2 mm wide, the filaments of 4 median stamens 2-3.3 mm, of 2 large abaxial ones dilated and 5-7 mm, of the sterile centric abaxial one 3-4 mm, the anthers of 4 median stamens including the 2-lipped ascending beak 3.2-5.2 mm, those of 2 large abaxial ones, measured from base to constriction beneath the beak, 3.7-5 x 1.1-1.5 mm, the beak 1.2-1.6 mm, its thickened tonguelike abaxial lobe (0.6-)0.8-1.2 mm, the anther of the centric stamen up to 2 x 0.6 mm, but often filiform or 0; ovary densely white- strigulose or -pilosulous; style glabrous, keeled laterally and ventrally, (3-)3.2-4.7 mm, a little dilated distally and 0.35-0.5 mm diam toward apex, the introrsely lateral stigmatic cavity elliptic-oblanceolate in ventral view, its margins explanate and barbellate along the sides, minutely porrect at tip; ovules 40-60 (average 51). Pod normally erect or ascending at narrow angles, sessile or almost so, linear, slightly incurved or less often straight, 8-13(-13.5) x (0.65)0.7-0.9(-0.95) cm, piano-compressed when young but ± distended when ripe, 2-carinate by the sutures, the remotely strigulose valves differentiated lengthwise into marginal bands of green (later stramineous) tissue issuing from the sutures and a central red or livid (later brown) band, this ± elevated over and depressed between each successive pair of seeds, the seminal cavities separated by complete membranous septa, mostly 1.5-2.5(-3, or the distal one -3.5) mm long; seeds all (or all but 1-few distal ones) turned so as to present their broad areolate faces to the septa, compressed-obovoid or -suborbicular (3.l-)3.4-4.7(-5.1) x (2.3-)2.9-3.8 mm, the dull olivaceous, fawn-brown or putty-colored, rarely castaneous testa minutely papillate or nearly smooth, the waxy exterior coat crackled in age; n = 14, reportedly sometimes = 13 in Old World.—Collections: 311.

Distribution and Ecology - Disturbed and waste places in forest, brush, savanna and riparian environments, in arable and pasture land, on roadsides, about farms and villages where sometimes planted for medicine, especially vigorous and abundant in ditches and seasonally moist depressions or on shores, mostly below 500 m but ascending to 1200 m in s. Mexico and on the Brazilian Planalto, now everywhere weedy in the New World, not demonstrably native and perhaps a paleotropical immigrant of long standing, interruptedly widespread almost throughout the American Tropics, but not recorded from the Pacific slope in Peru and absent from much of the Amazonian Hylaea, extending n. around the foothills of the Mexican Plateau into warm temperate Sinaloa and Tamaulipas, thence n.-e. in United States around the Gulf to peninsular Florida and n. in the e. and centr. States to ±36° as a self- perpetuating weed, casually further (cf. Iseley, 1975, map 51), in S. America s. to Parana in Brazil, and to n.-w. and n.-e. Argentina (Salta and Tucuman; Misiones and Corrientes). Also widespread in similar habitats almost throughout tropical Africa, India, Sri Lanka, Indochina, s. China, Malesia, n. Australia, and e. through Micronesia to Hawaiian Is.—Fl. in favorable circumstances throughout the year, in temperate climates in midsummer and fall.

Discussion

With the exception of S. obtusifolia, the Coffee Senna is the weedy member of its genus most widespread over tropical lowland and warm temperate America, a coarse ill-scented plant that colonizes roadside ditches, rundown or abandoned farmland, and disturbed places sometimes far from habitations. It is often but needlessly confused with C. obtusifolia; at anthesis its basal petiolar gland and leaflets broadest below, not above the middle, and later on the wider shorter pod (mostly 7-9, not 2.5-6 mm broad) distinguish it handily. Its closest relatives are the local Argentine S. scabriuscula, mentioned at greater length above, and the equally weedy but more local S. sophera, different in its more fruticose stems, smaller and slightly more numerous leaflets, pedunculate racemes and subterete pod dilated when ripe by seeds disposed in two parallel rows. From these and from all other American oncolobiums, however, S. occidentalis is definitively separable by the form of the style-tip, as described in our key to the series; and S. sophera alone shares the relatively large stipules commonly auriculate-clasping on the side further from the petiole. The ordinarily erect or narrowly ascending pod of S. occidentalis varies from straight to gently arched, but if curved at all it is incurved toward vertical, with seminiferous suture concave, not arched outward like that of all other oncolobiums except S. scabriuscula. In spite of its immense range and edaphic adaptability, S. occidentalis appears very uniform genetically. Individuals differ much in stature, due to age and accidents of environment, and there is some variation in flower-size, but pubescence, androecium and pod are essentially stable and the species is the most easily defined American member of its group. It is likely that the strains established in southeastern United States and perhaps those in extratropical Argentina have been climatically selected for rapid, obligately monocarpic cycles of growth, but the individual plant so modified in behavior is phenetically identical to the immature phase of its tropical counterpart that has a life expectancy of two or three seasons and a potentially suffruticose maturity. There is conflict in the literature as to the origin of S. occidentalis. Bentham (1871) thought it probably derived from America, but some modern authors omit the qualification, though bring no evidence to bear on the question. The species is now a circumtopical ruderal whose dispersal has doubtless been hastened by real or imaginary medicinal virtues, and nothing of substance can be learned from its contemporary range. Historical data are ambiguous. The earliest known record is that of Willem Piso from northeastern Brazil in mid-XVII century, but it was found by Rumpf on Amboina only a few years later and by Plumier in the Antilles about 1690. In the Old World it has acquired so many common names in the tongues of Africa, Indomalaya and the Pacific islands that a familiarity of long standing to the peoples of those countries seems certain. The close relationship of S. occidentalis to S. sophera which, because its center of high variability is certainly in Asia, is presumed to be originally paleotropical, suggests that the American range of S. occidentalis is likewise derived. But if this is really so, the very closely allied S. scabriuscula, endemic to northeastern Argentina and adjacent Paraguay and Uruguay, can only be interpreted as a neo-species derived from S. occidentalis in post-Colombian times. A close biosystematic study of S. scabriuscula might clarify this point. But for the present we can form no firm opinion as to the origin of S. occidentalis. The use of the roasted seeds of S. occidentalis as a substitute coffee is established independently on three continents, even though the infusion contains neither caffein nor allied alkaloids. Medical uses are numerous, infusions of the leaves having tonic, diuretic, stomachic, febrifuge and anthelmintic properties, while analgesic poultices and skin ointments are prepared from stems and foliage. Quisumbing (Medicinal Pl. Philipp. 382-384. 1951) gives a full review of the subject. The plants are generally avoided by stock, and are toxic, sometimes fatally so, to cattle. Britton & Rose (1930, p. 257, sub Ditremexa) called attention to a remarkable lusus of S. occidentalis, collected in Florida by Chapman (NY!), in which the blade of all leaves is modified into an ample ovate terminal leaflet. This leaf stands in relation to the ordinary paripinnate one of Senna as that of Poissonia Baill. stands to the leaf of Coursetia DC. We have seen no further instance of this abnormality in the genus. The Guahibo Indians in Amazonas, Venezuela are reported to use a preparation of the seeds for heart pain, under the name morrocoy (Colchester 2012, K). The Madagascan vernacular natarova, meaning dies-at-evening, refers to the transient nature of the corolla.

Common Names

coffee senna, hedion-dilla, frijolillo, cornezuelo, Brusca, bicho , stinking weed, pois puant, p.p. noir, martinica , dandelion, styptic weed, chilinchile , potra , retamilla, mamuri, cafetillo, cafeton, cafe del campo, c. de Bonpland, taperiba , mata pasta, fedegoso (-a), taratucu, paramarioba, mata patinho

Distribution

Sinaloa Mexico North America| Tamaulipas Mexico North America| Paraná Brazil South America| Florida United States of America North America| Salta Argentina South America| Tucuman Argentina South America| Misiones Argentina South America| Corrientes Argentina South America| Peru South America| India Asia| Sri Lanka China Asia| Hawaii United States of America North America| Samoa Oceania|