Cultivation Details
The tree will grow in a range of climatic conditions, but is particularly suited to the lowland tropics with a monsoon climate, where it can succeed at elevations up to 1,300 metres[1]. It grows in areas where the mean annual rainfall ranges from 500 - 2,800 mm with an optimum of about 1,000 mm[1]. The maximum length of the dry period should not exceed 4 - 8 months[1]. Under semi-arid conditions (rainfall of 500 - 700 mm), it will only grow when its roots have access to groundwater[1]. It requires a mean minimum temperature of 20°c, ranging from 14 - 28°c, and a mean maximum temperature of 31°c, ranging from 24 - 36°c[1]. It is susceptible to cold and frost[1]. Requires a sunny position[1]. It grows best on deep, well-drained, fertile soils, but will succeed on degraded, lateritic soils provided drainage is not impeded[1]. It grows poorly on infertile, poorly drained podzolic soils[1]. It is not tolerant of salinity, but is reasonably tolerant of acid soil conditions[1]. It prefers a pH in the range 5.5 - 7.5[1]. Often grown as an ornament, the plant has escaped from cultivation in the Americas and has become abundantly naturalized in some areas[3]. In Australia the species is considered invasive and it has the potential to become as prolific in other tropical locations[4]. Trees grow fast even in comparatively infertile soils[1]. Seedling trees start flowering and fruiting at the age of 2 - 3 years[1]. Once established, they flower precociously and abundantly throughout the year[1]. Planting density varies according to use. In fuel wood plantations, spacing ranges from 1 x 1 metre to 1x 3 metres. In hedges used for alley cropping or as a shelterbelt, spacing between plants in the row should be 25 - 50 cm[1]. Trees respond well to coppicing[1]. For the production of fuel wood and charcoal, plantations are generally pollarded or regenerated by coppice leaving 2-3 shoots/stump after 1 year. It has been reported that sapwood should be removed as soon as possible after felling to prevent insect attack of the heartwood[1]. The root system consists of a few thick roots, growing to considerable depth, and a dense mat of rootlets in the top 10 - 20 cm of soil, which may reach a distance of 7 metres from the stem in 1 year and eventually a distance up to 15 metres[1]. Although many species within the family Fabaceae have a symbiotic relationship with soil bacteria, this species is said to be devoid of such a relationship and therefore does not fix atmospheric nitrogen[5].
Propagation
Seed - requires pre-treatment to soften the hard seedcoat and allow the ingress of water[6]. This can be done by soaking the seed in a small amount of nearly boiling water (which cools down quickly and does not cook the seed) and then soaking the seed for 12 - 24 hours in warm water. Alternatively, a small area of the seed coat can be abraded, being careful not to damage the embryo[PFAF]. Germination of treated seed is about 90% within 60 days. Germination of untreated seeds is about 75% in 4 - 29 days[1]. The seed is usually sown in situ[1]. Seeds should be sown in areas with full sunlight, as the slightest shade reduces germination considerably[1]. Early seedling growth can be quite slow, reaching only 29 cm after 8 weeks of planting[1]. Storage behaviour is orthodox. Viability can be maintained for 3 years in hermetic storage at room temperature with 11-15% mc. There are 35 000-45 000 seeds/kg[1]. Cite as: Tropical Plants Database, Ken Fern. tropical.theferns.info. 2026-02-20. <tropical.theferns.info/viewtropical.php?id=Senna+siamea>
Pollinators
Data unavailable
References
- [1]World Agroforesty Centre — http://www.worldagroforestry.org/ ↩︎An excellent online database of a huge range of trees giving very good information on each plant - its uses, ecology, identity, propagation, pests etc.
- [2]Plant Resources of Southeast Asia — http://proseanet.org/ ↩︎Lots of information on the uses of the plants of SE Asia.
- [3]Flora of Guatemala — Standley P.C. & J. A. Steyermark · 1946 - 1976 · http://www.archive.org/ ↩︎A superb reference, though somewhat dated. Gives lots of plant uses as well as information on plant habit and habitat. The entire flora (13 volumes) can now be downloaded from http://www.archive.org/
- [4]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
- [5]Nodulation Plants in GRIN Taxonomy — United States Department of Agriculture · http://www.ars-grin.gov/~sbmljw/cgi-bin/taxnodul.pl?language=en ↩︎An online database listing plants that have either positive or negative reports on root and stem nodulation with nitrogen-fixing bacteria.
- [6]Protabase - Plant Resources of Tropical Africa. — http://www.prota.org ↩︎An excellent on-line database with detailed information on over 3,200 species of useful plants of Africa.
- [7]The Hongmu Challenge; A briefing for the 66th meeting of the CITES Standing Committee, January 2016 — Environmental Investigation Agency; London · 2016 · http://www.eia-global.org ↩︎Lists the 33 species used in making Hungmu furniture and the degree of over-exploitation plus recommendations for protecting them.
- [8]Flora Malesiana Series 1 — Various · Nationaal Herbarium Nederiand, Universiteit Leiden branch · http://www.archive.org ↩︎A massive treatment of the plants of the Malaysian Archipelago. Much of it has been made available to download from the Internet
- [9]Digital Compendium of Forestry Species of Cambodia — www.digitalspecies.blogspot.com; Phnom Penh · 2008 · http://www.digitalspecies.blogspot.com ↩︎A very detailed booklet, produced in PDF format on the internet, giving information on around 100 species of trees.
- [PFAF]Plants for a Future — pfaf.org ↩︎