Sennor – Senna

Bark is often light-brown and smooth. Leaves are alternate, usually stipulate, even-pinnate (terminating with a pair of leaflets) with 5-20 pairs of leaflets, rachis and petiole with or without glands. Inflorescence is an axillary or terminal raceme or panicle, upright or pendulous. Flowers are irregular, 1.5-5 cm, yellow in most species, but reddish-yellow or pink in some. Calyx and corolla are 5-merous. Stamens are 10 (some may be reduced to staminodes), all filaments straight (Senna) or 3 sigmoidally curved and distinctly longer (Cassia). Fruit is an elongated legume, cylindric or compressed, indehiscent or dehiscent. Seeds are numerous.

Both Cassia and Senna are pantropical, a few species occur in temperate regions. They are cultivated throughout the tropics and subtropics.

Mostly deciduous trees, shrubs and herbs, up to 10-15 m tall.

Cassias and sennas are found in a wide range of habitats and climates. Unlike other legumes, they do not have nitrogen-fixing nodules in their roots.

Sennas and cassias have showy inflorescences, which make them popular ornamental and shade trees intropical and subtropical regions. They are also known as medicinal plants, especially as laxatives. Many species yield good timber for different purposes. Wood is also burned as firewood and charcoal. Flowers provide forage for bees. Leaves and fruits of some species are used as animal feed. Gum from the seeds of S. obtusifolia is a food additive (E427).

There has been, and still is, some confusion in the relationships of Cassia, Senna and the related genus Chamaecrista. Many species of Senna were previously included in Cassia. The two genera are therefore treated here together.

Keywords:

Ornamental, shade, medicine, timber, wood, fuel, bee forage, dye, animal feed, gum, Fabaceae.