Senna durangensis var. iselyi
Phytologia 44: 499. 1979.
Herbs, biennial, to 0.4 m. Leaves slightly sclerophyllous, 1.5–7.5 cm, hairy; stipules tardily deciduous; extrafloral nectary 1, between leaflet pair, subsessile; leaflet pairs 1, blades broadly, obliquely obovate, 20–40 × 14–23 mm. Racemes 1 or 2-flowered; bracts caducous. Pedicels 6–15 mm. Flowers monosymmetric; calyx caducous, pale green; corolla yellow, longest petal 7–12 mm; androecium not heterantherous, stamens 7, staminodes 3; anthers 2.2–3 mm, dehiscing by 1 apical pore, apical appendage 0; gynoecium nearly linear, ovules 38–44; ovary densely hairy; style linear. Legumes erect, flat to cylindrical, straight, 20–40 × 5 mm, corrugated over seeds, dehiscing apically downward, with 2 series of seeds. Seeds brown or olive brown, paddle-shaped or pyriform.
Phenology: Flowering mid spring–mid fall.
Habitat: Mesquite thickets, sandy banks, sandy loam soils, alluvial valleys, roadsides.
Elevation: 0–150 m.
Distribution
Tex., Mexico (San Luis Potosí, Tamaulipas).
Discussion
Variety durangensis, known from northern Mexico, is distinguished from var. iselyi by its 2–5-flowered inflorescences and the longest petals 11–13 mm. Variety iselyi has been reported from the trans-Pecos region of southern Brewster County, but the identification of materials from that region is tentative (A. M. Powell and R. D. Worthington 2018).
Selected References
None.