Senna alexandrina Mill.
Cassia senna L., C. lanceolata Forssk., C. acutifolia Delile.
Eng.: Alexandrian senna, Egyptian senna, east Indian senna. Spa.: Sen, sen de Alejandría. Fre.: Séné de la palthe. Ara.: Sena, senamiki, senna mekki, sana, salamekki. Tam.: Adjerdjer, agargar, aegirgir; the fruit: amaraeshoen.
Subshrub or shrub up to 1(2) m in height, hermaphrodite, evergreen, upright, multi-stemmed, highly branched almost from the base. Stems and old branches with whitish bark, glabrous, younger branches shortly hairy. Leaves 3-15(25) cm, alternate, paripinnate, stipules 3-5(9) mm, subulate or narrowly triangular, with petiole 1-2.2 cm, petiole and rachis eglandular and hairy, and with 2-8(13) pairs of leaflets 15-45(50) × 4-10(15) mm, subsessile, ovate-lanceolate or lanceolate, somewhat asymmetric, acute at the apex and sometimes mucronate, attenuate-rounded at the base, margin entire, pubescent, light green on the upper side and somewhat glaucous on the underside. Inflorescences racemiform, axillary, 5-30 cm, arranged in small clusters, erect, with many pedicellate flowers, with pedicels up to 4-6 mm at fruiting, glabrous or slightly pubescent. Calyx with 5 sepals fused into a short cupuliform structure, with 5-7 mm teeth, open in a star-shape, oblong or ovate-oblong, glabrous, greenish. Corolla with 5 petals 7-17 mm, open in a star-shape, ovate or obovate, yellow or yellowish-orange, with brown vernation, glabrous. Stamens 10, free, very unequal, 2 longer stamens, nearly as long as the petals and with linear arcuate anthers, the medium sized stamens shorter and with anthers straight almost as long as the filament, yellow-brown, and the 3 upper stamens transformed into staminodes. Ovary shortly hairy. Pod (3)4-7 × 1.6-2.6 cm, linear-oblong, highly compressed, with papery valves, and transversely ribbed-reticulate, green at first then yellowish-brown when mature, glabrous or hairy, with 6 -7(10) seeds separated by septa. Seeds 3-7 × (2)3-3.5(4) mm, obovoid, compressed, greenish, greyish or pale brown.
Flowering:
March to May, but also after the rains in other seasons.
Fruiting:
Usually from May to July, but it always depends on the rains.
Habitat:
Floodplains, banks of waterways and oases.
Distribution:
Drier half (desert and predesert) of North Africa and central-western Asia, reaching towards the E to India and Sri Lanka. In North Africa, mainly in the central and southern belts of the Sahara, reaching towards the N almost to the Mediterranean in Egypt. In some areas, its presence has been enhanced by its ancestral cultivation as a medicinal plant. It has been introduced in parts of Asia and the Americas.
Observations:
With the leaves and pods of this species, a herbal tea (known as “Senna tea”) is prepared, known for its purgative properties, especially in India.
Conservation status:
A relatively common and widespread species, not considered threatened. In the IUCN Red List of Threatened Species, it is listed as Least Concern (LC) at global level. In Mali they are all included in its List of species that need authorization for commercial use (Decree 07-155/P-RM of 2007).