Author: Mill.
Morphological description
Herbs , shrubs and small trees .
Leaves spirally arranged; paripinnate (Senna spectabil infl&lvs 139520 ); extrafloral nectaries present or not.
Inflorescences racemose, axillary and/or terminal; bracteoles absent.
Flower: Calyx 5-merous. Corolla zygomorphic; petals 5, subequal. Androecium basically 10-merous; filaments of all stamens straight; anther-thecae not ciliate along the sutures.
Pods either indehiscent or inertly dehiscent through 1 or both sutures, in the last case not coiling or the valves breaking up in 1-seeded joints (Senna alata compl 428845 ).
Seeds and funicle variable.
Distribution
A pantropic genus with c. 260 species, c. 1/5 of these in the warmer parts of the Americas. 17 species are treated here, 3 of them indigenous (see Note 1 below).
Notes
1. In Malesia probably only 3 species are indigenous: Senna divaricata , Senna timoriensis and Senna tora . It is doubtful whether Senna siamea is indigenous and the remaining 14 species have all been introduced. Some of them are probably only occasionally met with outside gardens. There are others which Larsen & Ding Hou (1996: 673) have decided not to include in the key as they have never had any larger distribution as garden plants and are hardly found in any natural vegetation type. A number of taxa, occasionally recorded as in cultivation in Malesia have not been included. See list of excluded species below.
2. For details on synonymy, literature and typification of the genera Cassia , Chamaecrista and Senna , the reader/user is referred to the comprehensive revisions by De Wit (1956: 197-292) and Irwin & Barneby (1982: 64).
3. See the Note under Genus Cassia for the reasons to recognize Senna and Genus Chamaecrista as genera separate from Cassia .
4. The Genus Senna differs from the Genus Cassia in lacking bracteoles, whereas , and in having straight filaments in all stamens, in stead having 3 fertile stamens with sigmoid curved filaments (FIGS).
Excluded species
A number of species have occasionally been recorded as in cultivation in Malesia . They have not been included in the present treatment. See also under Cassia .
Senna auriculata (Linnaeus) Roxburgh (basionym Cassia auriculata Linnaeus) is a species native to India, Burma and Sri Lanka; formerly it was cultivated in Java and W Malaysia where the bark was used for tanning. According to literature it did not seed readily and is difficult to propagate. It is probably no more in use. See Maman Rahmansyah (1991: 62-63) sub Cassia auriculata . There is one specimen in L collected from a garden in the Philippines.
Senna didymobotrya (Fresenius) Irwin & Barneby (basionym Cassia didymobotrya Fresenius) from E Africa, which is very rarely cultivated in gardens. There is one collection in L collected from New Guinea.
Senna multiglandulosa (Jacquin) Irwin & Barneby (syn. Cassia tomentosa Linnaeus f.; Cassia multiglandulosa Jacquin) is indigenous to tropical America. It is cultivated in Malesia as ornamental, but no collection was seen from this region.
Senna galegifolia (Linnaeus) Barneby & Lourt. (basionym Cassia galegifolia Linnaeus; syn. Cassia biflora Linnaeus, nom. ambig.; Cassia pallida Vahl; Senna pallida (Vahl) Irwin & Barneby) is a S American species very rarely grown in gardens. It has been reported as a garden plant in W Malaysia. There is no material found in L.
Senna splendida (Vogel) Irwin & Barneby (basionym Cassia splendida Vogel) is native to S America. It is very rarely grown in gardens. There is no material collected from Malesia in L.