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coffee senna, septicweed

Habit 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.

Senna occidentalis

Phenology Flowering mid summer–early winter.
Habitat Disturbed habitats, waste places, roadsides.
Elevation 0–1200 m. (0–3900 ft.)
Distribution
from FNA
AL; AR; FL; GA; IA; IL; IN; KS; LA; MA; MD; MO; MS; NC; NY; OK; SC; TN; TX; VA; Mexico; Central America; South America; West Indies [Introduced in North America; introduced also in tropical and subtropical Eurasia, Africa, Australia]
[WildflowerSearch map]
[BONAP county map]
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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 11.
Parent taxa Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Senna
Sibling taxa
S. alata, S. armata, S. artemisioides, S. atomaria, S. bauhinioides, S. corymbosa, S. covesii, S. durangensis, S. hebecarpa, S. hirsuta, S. ligustrina, S. lindheimeriana, S. marilandica, S. mexicana, S. multiglandulosa, S. obtusifolia, S. orcuttii, S. pendula, S. pilosior, S. pumilio, S. ripleyana, S. roemeriana, S. surattensis, S. wislizeni
Synonyms Cassia occidentalis, Ditremexa occidentalis
Name authority (Linnaeus) Link: Handbuch 2: 140. (1829)
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