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Roemer senna, twoleaf senna, twoleaf wild sensitive plant

Coues' cassia, Coves' cassia, desert 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 0.7 m. Leaves slightly sclerophyllous, 2–10 cm, hairy; stipules persistent, to 1 mm wide; extrafloral nectaries between all leaflet pairs, stipitate; leaflet pairs 2–4, blades obovate to elliptic-obovate or oblong-elliptic, 10–38 × 5–19 mm.
Racemes

1–5-flowered;

bracts caducous.

(2–)4–8-flowered;

bracts caducous.

Pedicels

9–16 mm.

8–17 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 pale green, pinkish, or yellowish;

corolla golden yellow, longest petal 9–15 mm;

androecium not heterantherous, stamens 7, staminodes 3;

anthers 2.5–4.2 mm, dehiscing by 1 apical pore, apical appendage 0;

gynoecium linear, slightly incurved, ovules 28–42;

ovary hairy;

style filiform, incurved.

Legumes

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

erect, cylindrical, slightly curved, 180–350 × 50–80 mm, shallowly corrugated over seeds, dehiscing apically downward.

Seeds

brown or pinkish brown, paddle-shaped or pyriform.

brown, rhomboid.

2n

= 28.

Senna roemeriana

Senna covesii

Phenology Flowering spring–early fall. Flowering late winter–early fall.
Habitat Mesquite grasslands, chaparral, draws in shortgrass prairies, barren hillsides, desert washes, roadsides. Sandy and gravelly desert washes, slopes, and stony hills, disturbed desert roadsides.
Elevation 100–2000 m. (300–6600 ft.) 0–1200 m. (0–3900 ft.)
Distribution
from FNA
NM; OK; TX; Mexico (Chihuahua, Coahuila, Nuevo León)
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NM; NV; Mexico (Baja California, Sinaloa, Sonora)
[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. 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. roemeriana, S. surattensis, S. wislizeni
Synonyms Cassia roemeriana, Earleocassia roemeriana Cassia covesii, Earleocassia covesii
Name authority (Scheele) H. S. Irwin & Barneby: Mem. New York Bot. Gard. 35: 282. (1982) (A. Gray) H. S. Irwin & Barneby: Phytologia 44: 499. (1979)
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