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coffee senna, septicweed

trans-Pecos senna

Habit Herbs, perennial, bushy, to 2.2 m; branches dark green and blackish. Herbs, perennial, to 0.7 m. Leaves slightly sclerophyllous, 1.5–7.5 cm, hairy; stipules tardily deciduous; extrafloral nectary 1, between leaflet pair, stipitate; leaflet pairs 1, blades broadly, obliquely obovate to oblong-obovate, 15–40 × 10–25 mm.
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.

2–6-flowered;

bracts caducous.

Pedicels

8–21 mm.

6–15 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.

monosymmetric;

calyx persistent into developing fruit, pale green;

corolla yellow, longest petal 8.5–10 mm;

androecium not heterantherous, stamens 7, staminodes 3;

anthers 2.3–3.7 mm, dehiscing by 1 apical pore, apical appendage 0;

gynoecium nearly linear, ovules 16–26;

ovary densely hairy;

style linear.

Legumes

ascending, flat, slightly curved or straight, linear, 80–135 × 6.5–9.5 mm, corrugated over seeds, dehiscent.

erect, flat, straight, 20–40 × 5.5–7.5 mm, corrugated over seeds, dehiscing apically downward, with 1 series of seeds.

Seeds

olive green or brownish, obovoid.

dull pinkish or grayish brown, pyriform.

2n

= 26, 28.

= 28.

Senna occidentalis

Senna pilosior

Phenology Flowering mid summer–early winter. Flowering spring–mid fall.
Habitat Disturbed habitats, waste places, roadsides. Sandy banks, desert washes.
Elevation 0–1200 m. (0–3900 ft.) 600–1500 m. (2000–4900 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]
from FNA
TX; Mexico (Chihuahua, Coahuila, Durango)
[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.)

Senna pilosior is the only senna in North America with sepals persisting into fruit development and falling off before fruit matures and dehisces. Persistent sepals are diagnostic to distinguish S. pilosior from the close relatives S. bauhinioides and S. durangensis; the trio is, in fact, characterized by a history of repeated misidentifications (H. S. Irwin and R. C. Barneby 1982).

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

Source FNA vol. 11. FNA vol. 11.
Parent taxa Fabaceae > subfam. Caesalpinioideae (excluding Mimosoid clade) > Senna 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
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. occidentalis, S. orcuttii, S. pendula, S. pumilio, S. ripleyana, S. roemeriana, S. surattensis, S. wislizeni
Synonyms Cassia occidentalis, Ditremexa occidentalis Cassia bauhinioides var. pilosior, C. pilosior
Name authority (Linnaeus) Link: Handbuch 2: 140. (1829) (B. L. Robinson ex J. F. Macbride) H. S. Irwin & Barneby: Phytologia 44: 500. (1979)
Web links