Herbs, perennial, bushy, to 2.2 m; branches dark green and blackish. Leaves meso­phyllous, 11–26 cm, glabrous or glabrate; stipules caducous; extrafloral nectary 1, base of petiole, sessile or subsessile; leaflet pairs 4 or 5(or 6), blades lanceolate- or ovate-acuminate, 45–100 × 12–38 mm. Racemes usually (1 or)2–5-flowered; bracts caducous, longer than bud, often blackish green. Pedicels 8–21 mm. Flowers monosymmetric; calyx pinkish or fuscous; corolla yellow, longest petal 12–17 mm; androecium heterantherous, stamens 6, staminodes 3 + 1; anthers of middle stamens 3.2–5.2 mm, of abaxial stamens 4.9–6.6 mm, elongated beyond pores, dehiscing by U-shaped pore, apical appendage linguiform, thickened; gynoecium incurved, ovules 40–60; ovary densely hairy; style slightly incurved. Legumes ascending, flat, slightly curved or straight, linear, 80–135 × 6.5–9.5 mm, corrugated over seeds, dehiscent. Seeds olive green or brownish, obovoid. 2n = 26, 28.

Phenology: Flowering mid summer–early winter.
Habitat: Disturbed habitats, waste places, roadsides.
Elevation: 0–1200 m.

Distribution

• Generated Map
• Legacy Map

Introduced; Ala., Ark., Fla., Ga., Ill., Ind., Iowa, Kans., La., Md., Mass., Miss., Mo., N.Y., N.C., Okla., S.C., Tenn., Tex., Va., Mexico, West Indies, Central America, South America, introduced also in tropical and subtropical Eurasia, Africa, Australia.

Discussion

Although Senna occidentalis is probably native to the tropical New World, the species is now weedy in so many countries worldwide, including also other parts of the New World, that the exact range of its geographic distribution as a native is a matter of speculation (H. S. Irwin and R. C. Barneby 1982). In the flora area, it is considered as naturalized (R. Kral et al. 2012; R.

Selected References

None.

Lower Taxa

None.