Senna septemtrionalis

Author: (Viviani) Irwin & Barneby

Morphological description
Evergreen shrub or small tree up to 4 m, young branches smooth, green (septemtri Senna inf/lf 428849). Stipules narrowly lanceolate, acuminate, 3-7 mm long, early caducous.

Leaves paripinnate with 3-4(-5) pairs of leaflets; petiole 1.5-5 cm long, glabrous, grooved; rachis 6-12 cm long, bearing a clavate or conical gland between all except the upper pair of leaflets; petiolules c. 2 mm. Leaflets ovate to ovate-elliptic, 4-11 by 1.5-3.5 cm, glabrous on both surfaces; apex acute to acuminate, base rounded to cuneate.

Inflorescence: Racemes axillary or terminal, 4-10-flowered, 5-10 cm including the 2.5-4 cm long peduncle; bracts linear-lanceolate, 2-5 mm, caducous; bracteoles absent; pedicels 1.5-2.5 cm long, glabrous (septemtri Senna infl 431601).

Flower: Sepals 5, yellowish-green, ovate-elliptic, unequal, 4-10 mm. Petals 5, bright yellow, ovate orbicular, shortly clawed, glabrous, 1-1.5(-2) cm. Stamens 10: 2 long with filaments dilated, ribbon-like, 8-11 mm with anthers 8 mm, curved, opening by an apical pore; one with similar anther but with filament 4 mm; 4 with filaments 2 mm long and anthers 4-5 mm; 3 staminodes with anthers flat, non-functioning, suborbicular; filaments of all stamens straight. Ovary glabrous; style linear; stigma inconspicuous.

Pods terete, slightly subquadrangular when fully mature, tardily dehiscent, 6-10 cm, c. 1 cm diameter (septemtri. Senna lv/pod 139593 ).

Seeds 50-70, obovoid, olive, glossy, flat, 5-6 mm.

Origin uncertain but neotropic, apparently native to Mexico and C America. Since pre-Columbian times cultivated for medical purposes and widely spread; long established in the Old World tropics including Malesia: Sumatra, the Malay Peninsula, Java, and New Guinea.

In the Malesian area escaped from cultivation and occurring as a weed up to 2500 m altitude, along waysides and ditches, also in grasslands and young secondary forests.

Cultivated as ornamental and as a hedge plant.