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Description |
Notes on Taxonomy and Nomenclature
The genus Senna Mill. (Caesalpiniaceae) is represented by 350 species, of which about 80% are from the New World (Irwin and Barneby, 1982; Rahman et al., 2013). The genus name is derived from the Arabic “sana”, which refers to the laxative leaves and pods (National Parks Board, 2016). Senna is characterised by having cylindrical or flattened, irregularly dehiscent pods, the longest stamens having the anthers facing each other to deposit pollen on the sides of visiting bees and the seeds being usually areolate (Irwin and Barneby, 1982). Senna species were originally included by Linnaeus in his concept of Cassia, and until 1982, when Irwin and Barneby split the subtribe Cassiinae into three genera, many authors included Senna and Chamaecrista species in a broadly circumscribed Cassia.
The common name of S. alata, candle bush, refers to the raceme inflorescence resemblance to a candle with the buds covered with orange bracts that look like a flame. It is also sometimes called ringworm bush due to its fungicidal properties. The epithet alata refers the winged pods (National Parks Board, 2016).
Description
The following description is from Flora of China Editorial Committee (2016):
Shrubs, 1.5-3(-5) m tall. Branches greenish, thick, pubescent. Leaves 30-60 cm; stipules persistent, triangular, 6-10(-15) mm; petiole and rachis with 2 longitudinal ribs and narrow wings; petiolar glands absent; petiolules very short or leaflets subsessile; leaflets 6-12(-20) pairs, oblong or obovate-oblong, 6-15 × 3.5-7.5 cm, thinly leathery, glabrous, base obliquely truncate, apex obtusely rounded and cuspidate. Racemes axillary, dense, many flowered, or sometimes several racemes forming a terminal panicle, 10-50 cm; peduncles 7-14 cm; bracts caducous, strobilaceous, oblong to broadly ovate, 2-3 × 1-2 cm, at first enveloping flowers. Flowers ca. 2.5 cm in diam. Sepals orange-yellow, oblong, unequal. Petals bright yellow, tinged with conspicuous purple veins, ovate-orbicular, 16-24 × 10-15 mm, shortly clawed. Stamens 10, fertile stamens 7, opening with apical pores, lower 2 with stout filaments ca. 4 mm and larger anthers, 4 with filaments ca. 2 mm and smaller anthers, reduced stamens 3 or 4. Ovary puberulent, sessile; ovules many. Legume winged, sharply tetragonal, 10-20 × 1.5-2 cm, glabrous, with a broad, membranous wing down middle of each valve; wings 4-8 mm wide, papery, crenulate. Seeds 50-60, compressed, deltoid.
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