Senna hirsuta
(hairy senna)

Preferred Scientific Name

• Senna hirsuta (L.) H.S.Irwin & Barneby

Preferred Common Name

• hairy senna

Other Scientific Names

• Cassia caracasana Jacq.
• Cassia hirsuta L.
• Cassia leptocarpa Benth.
• Cassia tomentosa Arn.
• Cassia venenifera G.Mey.
• Ditremexa hirsuta (L.) Britton & Wilson

International Common Names

• English: shower tree senna; slimpod glaberrima senna; stinking cassia; woolly senna; woolly wild sensitive plant

Local Common Names

• Indonesia: kasingsat ; kasingsat bulu
• Malaysia: kacang kayu; kacang kayu; sinteng
• Philippines: balbala tufigan; katanda; tighiman
• Thailand: dapplit; phong pheng

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Fabales
•                         Family: Fabaceae
•                             Subfamily: Caesalpinioideae
•                                 Genus: Senna
•                                     Species: Senna hirsuta

Until the beginning of the 1980s the Cassia genus was considered to be a very large genus of over 500 species. Bentham (1871) wrote that three groups within the Cassia genus were so distinct from one another that any species can always be unequivocally allocated to one of them; some main distinctions included fruit structure, stamen structure and arrangement, and nodulation (Lock, 1988). However it was not until 1982 that Irwin and Barneby formally separated Cassia into three genera: Cassia L. emend. Gaertner, Senna Miller, and Chamaecrista Moench. Cassia now has only about 30 species, whereas Senna and Chamaecrista comprise about equal numbers of species, about 260 and 270 respectively (Irwin and Barneby, 1982).

These three genera are now largely accepted and together make up the subtribe Cassinae. Cassia and Senna differ principally in stamen organization, and in arid areas of Australia, taxonomic distinctions between and within the three genera are blurred by polyploidy, hybridization and apoximis (Lewis et al., 2005). In 1988, Lock presented new names and combinations for the Cassinae species in Africa, noting that “if Cassia were to continue to be used in its broad sense in Africa, there would be several species which would be consistently given different names in different continents” (Lock, 1988). Approximately 80% of the Senna genus’ 260 or so species occur in New World tropical and subtropical areas, extending into warm temperate and rarely into cool temperate areas of both hemispheres with species in Africa, Madagascar, Australia, and a few in southeastern Asia and Pacific islands (Irwin and Barneby, 1982; Lock, 1988; Wagner et al., 2014).

S. hirsuta comprises a complex of seven varieties (Queensland Government, 2016). The species epithet and common name of hairy senna both stem from the long pale hairs covering the stems, leaves and pods of the plant.

The following description is taken from The Flora of China Editorial Committee (2017).

Herbs or shrubs, 0.6-2.5 m tall. Young branches, petioles, and rachises of leaves densely yellowish brown villous. Leaves 10-20 cm; petiole 3-6 cm, with a sessile, blackish brown, ovoid-oblong gland near insertion; rachis 7-10 cm, without glands; leaflets 3-7 pairs, ovate-oblong or oblong-lanceolate, 3-9 x 1.5-3.5 cm, papery, both surfaces villous, base subrounded, apex acuminate. Racemes axillary or several in axils of apical leaves forming a leafy panicle; peduncles and pedicels villous; bracts early caducous, subulate, hairy. Sepals 5, unequal in size, densely villous, 2 outer small, ovate to obovate, ca. 5 mm, 3 inner puberulent, similar but larger, 7-8 mm. Petals yellow, obovate, 1.4-1.8 cm, glabrous. Stamens 10, 6 or 7 of them fertile, unequal in length, anthers opening by apical pores, staminodes 3 or 4. Ovary hirsute, subsessile; style short, glabrous; stigma small. Legume long, slender, flat, 10-20 x ca. 0.5 cm, densely hirsute on surfaces of valves. Seeds numerous, flat, obovoid, 3-4 mm.

Depending on the variety of S. hirsuta, it may be erect or diffuse or simple or multi-stemmed (Csurhes, 2016).

S. hirsuta was first reported in Queensland, Australia in 1959 where it is likely to have been intentionally introduced as an ornamental (Queensland Government, 2016). It is now a restricted invasive plant here, listed under the Biosecurity Act 2014 (Queensland Government, 2016).

Seeds of S. hirsuta are dispersed by water, and by animals which eat the pods and translocate the seeds to a new location (BioNet-EAFRINET, 2017). Seeds of S. hirsuta are also readily spread accidentally as a contaminant of mud on footwear, machinery and vehicles (BioNet-EAFRINET, 2017).

In Kenya, S. hirsuta is regarded as a weed of degraded land and roadsides that threatens the habitats of indigenous species. In Queensland, Australia this species is an environmental weed. S. hirsuta has been listed as a noxious weed in South Africa (Csurhes, 2016; BioNet-EAFRINET, 2017).  

• Proved invasive outside its native range
• Has a broad native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Tolerant of shade
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year

• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - shading
• Competition - smothering
• Pest and disease transmission
• Rapid growth

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally deliberately

S. hirsuta has been proposed as a green manure and forage plant, but research has so far not confirmed its potential (PROSEA, 2016). It has been planted in certain parts of Africa as a shade plant in young coffee plantations (BioNet-EAFRINET, 2017). Leaves and young pods are also eaten usually steamed or cooked in vegetable dishes or in salads. In Java the leaves are used medicinally for treating herpes. A decoction of the leaves is used against irritation of the skin in Thailand. In Laos the seeds are used as a substitute for coffee (Csurhes, 2016).