Senna (genus)

Senna is a large genus of about 250–260 species of flowering plants in the family Fabaceae, subfamily Caesalpinioideae. This diverse genus is native throughout the tropics, with a small number of species reaching into temperate regions.

Typically Senna species have yellow flowers. Some species of Senna are notable for being host to particular butterfly species &mdash; for instance Cloudless Sulphur butterflies.

Senna alexandrina is a small shrub, about 0.5-1 m high, with a pale green smooth erect stem, long spreading branches, bearing four or five pairs of leaves. The flowers are small and yellow, the pods broadly oblong and containing about six seeds.

Senna is an Arabian name, and the plant is grown mostly in Nubia. Twice a year the plants are cut down, dried in the sun, stripped and packed in palm-leaf bags and sent on camels to Essouan and Darao then up the Nile to Cairo or else to Red Sea ports.

It is a purgative, similar to aloe and rhubarb in having as active ingredients anthraquinone derivatives and their glucosides. Its action is on the lower bowel, and is especially useful in alleviating constipation. It increases the peristaltic movements of the colon.

Another species of senna, Cassia obovata, is used as a hair treatment with effects similar to henna, but without the red color. The active component is an anthraquinone derivative called chrysophanic acid, which is also found in higher concentrations in rhubarb root. It adds a slight yellow color. Cassia obovata is often called "neutral henna".

Selected species

 * Senna aculeata
 * Senna acutifolia (syn. Cassia acutifolia; ِAlexandrian senna; Senna alexandrina)
 * Senna alata (Candle Bush)
 * Senna angulata
 * Senna armata
 * Senna artemisioides
 * Senna auriculata
 * Senna australis
 * Senna bicapsularis
 * Senna birostris
 * Senna candolleana
 * Senna corymbosa
 * Senna covesii, (Desert senna, Rattleweed)
 * Senna cumingii
 * Senna didymobotrya
 * Senna fruticosa
 * Senna hebecarpa
 * Senna helmsii
 * Senna hirsuta
 * Senna italica
 * Senna ligustrina
 * Senna lindheimeriana
 * Senna macranthera
 * Senna marilandica
 * Senna multiglandulosa
 * Senna multijuga
 * Senna nicaraguensis
 * Senna nitida
 * Cassia obovata
 * Senna obtusifolia
 * Senna occidentalis
 * Senna odorata
 * Senna oligophylla
 * Senna pallida
 * Senna purpusii
 * Senna siamea (syn. Cassia siamea; Siamese cassia; Siamese senna)
 * Senna wislizeni Shrubby Senna, Wislizenus' Senna (syn. Cassia wislizeni, Palmerocassia wislizenii)

Medicinal use
Because of the presence of anthraquinones, senna species are used as the primary ingredient in certain commercial stimulant laxatives. It is also the primary ingredient found in most "dieter's tea."

Culinary use
In some Southeast Asian cuisines (particularly those of Thailand and Laos), the leaves and flowers of Siamese Cassia (Senna siamea, called khi-lek in Thai), either fresh or pickled in brine, are used in cooking, particularly in gaeng khi-lek (khi-lek curry).