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Roemer senna, twoleaf senna, twoleaf wild sensitive plant

American senna, northern wild senna

Habit Herbs, perennial, to 0.7 m. Leaves slightly sclerophyllous, 2.5–9.5 cm, hairy; stipules caducous; extrafloral nectary 1, between leaflet pair, shortly stipitate; leaflet pairs 1, blades lanceolate-oblong or lanceolate, 20–70 × 4–14 mm. Herbs, perennial, to 0.8–2.2 m.Leaves mesophyllous, 13–23 cm, finely hairy; stipules caducous; extrafloral nectary 1, base of or along petiole, sessile or shortly stipitate; leaflet pairs 6–10, blades elliptic, oblong-elliptic, or lanceolate-elliptic, 30–60 × 10–20 mm.
Racemes

1–5-flowered;

bracts caducous.

25–37-flowered;

bracts caducous.

Pedicels

9–16 mm.

11–22 mm.

Flowers

monosymmetric;

calyx caducous, pale green;

corolla yellow or orange-yellow, longest petal 12–17 mm;

androecium not heterantherous, stamens 7, staminodes 3;

anthers 2.2–3.3 mm, dehiscing by 1 apical pore, apical appendage 0;

gynoecium nearly linear, ovules 22–40;

ovary densely hairy;

style slightly incurved.

monosymmetric;

calyx pinkish brown;

corolla yellow, longest petal 8–12 mm;

androecium heterantherous, stamens 7, staminodes 3;

anthers of middle stamens 2.6–3.5 mm, of abaxial stamens 4–5 mm, truncate, dehiscing by 2 pores, apical appendage 0;

gynoecium incurved, ovules 10–16;

ovary densely hairy;

style incurved, not dilated.

Legumes

erect, subcylindrical, straight or slightly curved, 20–35 × 4.5–6.5 mm, corrugated over seeds, dehiscing apically downward.

ascending, flat, curved downward, 60–115 × 5.5–8 mm, corrugated over seeds, tardily dehiscent, each seed compartment nearly as wide as long.

Seeds

brown or pinkish brown, paddle-shaped or pyriform.

ochre, yellowish brown, or dark reddish brown, ovoid or rhomboid.

2n

= 28.

Senna roemeriana

Senna hebecarpa

Phenology Flowering spring–early fall. Flowering mid summer–early fall.
Habitat Mesquite grasslands, chaparral, draws in shortgrass prairies, barren hillsides, desert washes, roadsides. Open woodlands, valley floors, creek banks, swamps, thickets, pastures.
Elevation 100–2000 m. (300–6600 ft.) 0–500 m. (0–1600 ft.)
Distribution
from FNA
NM; OK; TX; Mexico (Chihuahua, Coahuila, Nuevo León)
[WildflowerSearch map]
[BONAP county map]
from FNA
CT; DE; IL; IN; KY; MA; MD; MI; MO; NC; NH; NJ; NY; OH; PA; TN; VA; VT; WV; ON
[WildflowerSearch map]
[BONAP county map]
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. occidentalis, S. orcuttii, S. pendula, S. pilosior, S. pumilio, S. ripleyana, S. surattensis, S. wislizeni
S. alata, S. armata, S. artemisioides, S. atomaria, S. bauhinioides, S. corymbosa, S. covesii, S. durangensis, S. hirsuta, S. ligustrina, S. lindheimeriana, S. marilandica, S. mexicana, S. multiglandulosa, S. obtusifolia, S. occidentalis, S. orcuttii, S. pendula, S. pilosior, S. pumilio, S. ripleyana, S. roemeriana, S. surattensis, S. wislizeni
Synonyms Cassia roemeriana, Earleocassia roemeriana Cassia hebecarpa, C. hebecarpa var. longipila, S. hebecarpa var. longipila
Name authority (Scheele) H. S. Irwin & Barneby: Mem. New York Bot. Gard. 35: 282. (1982) (Fernald) H. S. Irwin & Barneby: Mem. New York Bot. Gard. 35: 446. (1982)
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