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Published In: Handbuch zur Erkennung der nutzbarsten und am häufigsten vorkommenden Gewächse 2: 140. 1829. (Handbuch) Name publication detail

Project Name Data (Last Modified On 8/11/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Introduced


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3. Senna occidentalis (L.) Link (coffee senna, coffee weed)

Cassia occidentalis L.

Map 1698, Pl. 386 c–e

Plants annual, producing a disagreeable odor when bruised or crushed. Stems 1 to several, (5–)30–120 cm long, erect or ascending, usually unbranched, glabrous or with scattered, minute glandular hairs. Leaves with the petiole 2–3 cm long, the petiolar gland positioned near the base, about 1 mm long, more or less hemispherical, appearing sessile and broadest toward the base. Leaf blades 8–10 cm long, with 3–5 pairs of leaflets. Leaflets 2–7 cm long, 1.5–3.0 cm wide, ovate to broadly lanceolate, oblique at the base, angled or slightly tapered to a sharply pointed tip, the margins with a pale, narrow band and short, ascending hairs, the upper surface glabrous, the undersurface with scattered, minute glandular hairs. Inflorescences short racemes but often appearing as small clusters of 2–5 flowers or even solitary flowers, the flower stalks 3–6 mm long, becoming elongated to 10 mm at fruiting. Sepals unequal in size, variously 5–10 mm long, 2–3 mm wide, oblong to oblong-obovate, rounded to bluntly pointed at the tip, the margins often somewhat uneven, glabrous. Petals 9–14 mm long, 5–7 mm wide, oblanceolate to obovate. Stamens with the anthers yellow. Ovary 4–6 mm long, with loosely appressed or ascending hairs, the style 3–4 mm long. Fruits 7–14 cm long, 8–10 mm wide, arched upward at maturity, strongly flattened, sparsely to moderately hairy when young, becoming glabrous at maturity, relatively conspicuously impressed between the seeds, light brown with a lighter-colored margin at maturity. Seeds 4–5 mm long, 3–4 mm wide, oblong-obovate to obovate, slightly flattened, the surface often developing a fine network of cracks toward the margins at maturity, olive green to brown, more or less dull, the pleurogram usually slightly grayer than the remainder of the seed. 2n=28. August–September.

Introduced, uncommon, mostly in the Mississippi Lowlands Division (native range poorly understood, probably originally native to tropical and warm-temperate regions of the New World; in the U.S., perhaps native as far north as North Carolina, Arkansas, and Oklahoma, introduced as far north as Kansas, Iowa, Illinois, Indiana, New York, and Massachusetts, also Hawaii). Banks of rivers; also fallow fields, railroads, roadsides, and sandy, open, disturbed areas.

Senna occidentalis is a widespread weedy species similar to S. obtusifolia. See the treatment of that species for a discussion of uses and toxicity of the two taxa.



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