Click on images to enlarge
young plant (Photo: Forest & Kim Starr, CC BY)
mature plant (Photo: Forest & Kim Starr, CC BY)
mature pod (Photo: Forest & Kim Starr, CC BY)
mature leaves (Photo: Brenda Monchari)
mature pods among leaves (Photo: Brenda Monchari)
pods and terminal leaflets (Photo: Brenda Monchari)
flowers (Photo: Forest & Kim Starr, CC BY)
Senna septemtrionalis (Viv.) H.S.Irwin & Barneby
Cassia laevigata Willd.; Cassia septemtrionalis Viv.; Cassia floribunda sensu Brenan non Cav.; Cassia laevigata Willd.; Cassia elegansKunth.
Smooth senna, yellow shower, arsenic bush, buttercup bush, dooleyweed, laburnum, esenetoi (Maasai), omochegechege (Ekegusii), chul senetwet / senetwet apchimbek (Kipsigis), esenetoi (Maasai)
Fabaceae (Leguminosae): sub-family Caesalpinioideae
Mexico and Central America.
Locations within which Senna septemtrionalis is naturalised include southern Africa and some oceanic islands with warm climates.
In the region, this species is naturalised at low elevations in dry, disturbed areas, but occasionally at higher elevations in pastures and even margins of wet forest. It is a common garden escape in Nairobi area. It has been recorded in Kenya in northern Kenya, Rift Valley, Nairobi, Western and Nyanza, Masai and Coast floral regions.
The stem is rough, but hairless.
Pinnate leaves, smooth, bright green, paler beneath. The leaflets 3-4 (5) pairs, the distal ones larger, broadly ovate (egg-shaped in outline with broad end at base) to lanceolate, 3.5-10.5 cm long, 1.1-3.5 cm wide. Leaf apex acuminate or caudate, base obliquely rounded or tapered (cuneate). The glands are located on the leaf rachis, between the leaflets and not on the petiole.
The pedicels (12-25) mm long. Bracts sub-membranous, linear, lanceolate, or subulate, (1.5-) 2-4.5 mm long, caducous as pedicels begin to elongate; calyx lobes yellowish green, yellowish brown, or completely yellow, the outer ones relatively firm, ovate (egg-shaped in outline with broad end at base)-elliptic, 4-6.5 mm long, the inner ones submembranous, oblong-obovate (egg-shaped in outline but with the narrower end at the base) or suborbicular, 6.5-10 mm long; flower petals bright yellow and sometimes have brown veins - the standard obovate to obovate-flabellate, deeply emarginate, the others obovate, the longest petal 12-16 mm long; staminodes 3, obovate or suborbicular, (1.7-) 2-2.6 mm long; filaments of 4 median stamens 1.3-2.2 mm long, those of 2 abaxial stamens dilated, ribbon-like, 7-10.5 mm long, that of abaxial central stamen 2-4 mm long.
Fruit is a green pod that matures brown. Pods ascending on a stiff pedicel, chartaceous, cylindrical or obtusely quadrangular, 6-10.5 cm long, 0.8-1.1 cm wide, cavity moderately pulpy, divided into 2 parallel rows of cells. Seeds oriented with broad face to the septum, olive or brown, compressed-obovoid, 3.6-4.9 mm long, constricted at the hilum, smooth or minutely pitted, without an areole" more details are in (Wagner et al., 1999; pp. 701-702).
Reproduces by seed. This plant spreads by reseeding itself, but seeds may be contaminants of soil and in garden waste.
Senna septemtrionalis is very similar to S. occidentalis (coffee senna), S. hirsuta (hairy senna) and S. obtusifolia (sicklepod). These species can be distinguished by the following differences:
Senna septemtrionalis is a medicinal plant among some communities in Kenya. It is also a popular garden plant.
The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species.
The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.
The editors could not find any specific information on the control of this species.
Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.
Beentje, H.J. (1994). Kenya trees, shrubs and Lianas. National Museums of Kenya, Nairobi, Kenya, 722 pp.
Henderson, L. (2001). Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa. Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.
Wikipedia contributors. "Senna septemtrionalis." Wikipedia, The Free Encyclopedia. Accessed January 2011.
Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.
This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).
BioNET-EAFRINET Regional Coordinator: email@example.com