Senna surattensis
(golden senna)

Preferred Common Name

• golden senna

Other Scientific Names

• Cassia fastigiata Vahl
• Cassia glauca Lam.
• Cassia suffruticosa Roth
• Cassia surattensis Burm.f.
• Psilorhegma suffruticosa (Roth) Britton & Rose
• Senna speciosa Roxb.

International Common Names

• English: foetid cassia; glaucous cassia; glossy shower; glossy-shower senna; scrambled eggs bush; sickle senna; Singapore shower tree; sunshine tree
• Chinese: huang huai jue ming

Local Common Names

• Indonesia: kembang kuning
• Indonesia/Nusa Tenggara: kembang koning; kemoning; kuning
• Laos: dok sake; sak heng
• Malaysia: gelenggang
• Thailand: khilek-ban; songbadan
• USA/Hawaii: kalamona; kolomona

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

Until the beginning of the 1980s the genus Cassia 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; Sosef and Maesen, 1997). These three genera are now largely accepted and together make up 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).

The species S. surattensis is named after  the town of Surat, located near Bombay, India (Motooka et al., 2003; Quattrocchi, 2012). Two other Senna spp. and three Crotalaria spp. share S. surattensis’ vernacular name in Hawaii, kolomona or kalamona (‘glory of Solomon’) (Motooka et al., 2003).

The species has been much confused with Senna sulfurea (Collad.) H.S.Irwin & Barneby; S. surattensis has more numerous, smaller leaflets, smaller brachystylous flowers and shorter, short-stipitate pod (Irwin and Barneby, 1982; ILDIS, 2014). In historical literature the name Cassia glauca Lam. may refer to either of these species, as this name has been listed as a synonym for both Cassia surattensis Burm. f. (synonym of S. surattensis) and S. sulfurea (ILDIS, 2014; Missouri Botanical Garden, 2014). De Wit’s description of S. surattensis has also become muddled with that of S. sulfurea, adding further confusion to interpreting the literature (Irwin and Barneby, 1982).

Small trees, 3-6 m tall. Leaves 8-18 cm long, leaflets 6-10 pairs, the distal ones larger and proportionately narrower, obovate to elliptic obovate or oblanceolate, 2-5 cm long, 0.8-2 cm wide, upper surface green and usually glabrous, lower surface glaucous and sparsely appressed pubescent, especially along midrib, apex rounded, emarginate, base obliquely rounded or cuneate, clavate nectaries between the first, second, and sometimes third pairs of leaflets, stipules linear subulate, 4.5-13 mm long, caducous. Flowers in racemes 0.4-2.5 cm long, pedicels 15-25 mm long, bracts submembranous, ovate to lanceolate, 2-7 mm long, persistent until anthesis, then deciduous, the lowermost sometimes subtended by a clavate nectary; calyx lobes oblanceolate to oblong obovate, the outermost 3-4.4 mm long, inner ones 5.5-8 mm long; petals bright yellow or yellowish orange, ovate to oblong ovate, the longest one 16-24 mm long; fertile stamens 10, all nearly similar to one another, slightly increasing in size toward abaxial side of flower; filaments 9, 0.7-2 mm long, that of central abaxial stamen 1.5-3.5 mm long. Pods pendulous, chartaceous, strongly compressed, 7-10 cm long, 1.1-1.5 cm wide, base constricted into a stipe 0.5-0.7 cm long, the cavity with narrow interseminal septa. Seeds oriented transversely in 1 row, compressed parallel to the valves, pale brown, glossy, oblong ellipsoid, 5-6 mm long, the areole 2.7-3.6 mm long [taken from Wagner et al., 2014].

S. surattensis is considered to originate from Southeast Asia and possibly Malesia and Australia, but has now been widely introduced to tropical and subtropical regions around the world as an ornamental plant as well as for use as a hedge and shade tree in plantations (Little and Skolmen, 1989; Hanelt et al., 2001).

Date of introduction to the West Indies is uncertain, but the species is known to have been cultivated on St. Vincent and the Windward Islands before 1826 (Irwin and Barneby, 1982). Because the name Cassia glauca Lam. could refer to either S. surattensis or to S. sulfurea (Collad.) HS Irwin & Barneby in historical literature, as this name has been listed as a synonym for both Cassia surattensis Burm. f. (synonym of S. surattensis) and S. sulfurea (ILDIS, 2014; Missouri Botanical Garden, 2014), the species may have been included (as Cassia glauca Lam.) in Grisebach’s flora on the British West Indies, which reported it to be present in Jamaica, Saint Kitts, Antigua and St. Vincent, and native to Guadeloupe (which from current literature is unlikely) and the East Indies (Grisebach, 1859-1864). The species may have also been cultivated in Trinidad by 1870 (as Cassia glauca Lam.) (Prestoe, 1870). Introduction to Puerto Rico appears to have been relatively recent, as the species was not included in Bello’s flora of Puerto Rico (1881-1883); Irwin and Barneby (1982) report only that the species was cultivated in Puerto Rico sometime after 1826, after which time it became naturalized (Liogier and Martorell, 2000). Britton included Cassia glauca in his Flora of Bermuda (Britton, 1918).

In Hawaii, the species is thought to have been a post-James Cook (died 1779) introduction, and was naturalized there by 1871 (Little and Skolmen, 2003; Motooka et al., 2003). In Sri Lanka, the species was introduced but has been present on the island since 1824, described by Moon by the name C. glauca (Moon, 1824).

S. surattensis has spread across tropical and subtropical regions around the world primarily as a result of its intentional cultivation by humans for ornamental and agroforestry purposes, and by accidental escape into the wild. The species produces seeds profusely, with up to 20 seeds per pod (Little and Skolmen, 1989; PIER, 2014). However, dispersal by birds and animals is considered unlikely, given that the pods do not have pulp to attract them (PIER, 2014). Wind dispersal is also unlikely, as the seeds are too heavy to be dispersed by wind, and pods remain attached to the plant so the seeds do not fall to the ground and germinate, causing them to rot on the plant (Poorten and Poorten, 2012).

The species has naturalized in many places after escaping from cultivation, and has been recognized as negatively impacting native environments where it can establish; in Hawaii, for example, it is known to shade out forages in mesic pastures (Motooka et al., 2003). Despite this, S. surratensis is valued in agriculture as a shade and hedge tree. Economically, it is a popular ornamental that has been introduced around the world for this reason, with its attractive flowers that bloom throughout the year and tolerance for SO2-polluted air (Sosef and Maesen, 1997; University of Florida-IFAS, 2014). 

• Invasive in its native range
• Proved invasive outside its native range
• Abundant in its native range
• Pioneering in disturbed areas
• Benefits from human association (i.e. it is a human commensal)
• Has propagules that can remain viable for more than one year

• Negatively impacts agriculture
• Reduced native biodiversity

• Competition - shading

• Highly likely to be transported internationally deliberately

S. surratensis is cultivated as a shade tree and as a hedge and ornamental plant; its leaves are used locally in traditional medicine (Hanelt et al., 2001), and its bark is said to be medicinal (Little and Skolmen, 1989).

In Southeast Asia, its young leaves are cooked and eaten as a vegetable, and in the Philippines, it is often used in teak plantations as a shade tree and hedge plant. The roots are used to treat gonorrhoea, the leaves for dysentery, and the flowers as a general purgative (Sosef and Maesen, 1997).