Gigasiphon macrosiphon is a medium-sized tree, one of three species in the genus Gigasiphon (family Fabiaceae, or legumes). A species potentially interesting to ornamental horticulturalists, it has large attractive white flowers striped with yellow and the tree grows to about 20 meters. The seeds are hard, smooth and button-shaped, with a light stripe around the perimeter. G. macrosiphon grows in moist lowland and coastal forests in Kenya and Tanzania. Continual destruction of East African coastal forests and use of this plant for firewood, tools, charcoal and lumber, has reduced the G. macrosiphon population to 33 known mature individuals in the wild. These are found in Kaya Muhaka, Gongoni, Marenje and Mrima Forest Reserves (Kenya) and Amani Nature Reserve, West Kilombero Scarp Forest Reserve, Kihansi Gorge and Rondo plateau (Tanzania). The IUCN assessed G. macrosiphon with endangered status in 1997 and in a report in conjunction with the Zoological Society of London (ZSL) placed this species on their list of 100 most endangered species in 2012.
(Baillie and Butcher 2012; CAMP Workshop 1998; Lovett et al. 2006; J.Robertson 1998; Verdcourt 1982)
- Baillie, J.E.M, and E.R. Butcher 2012. Priceless or Worthless? (PDF). Zoological Society of London. ISBN 978-0-900881-67-1. http://static.zsl.org/files/priceless-or-worthless-final-wq-2040-2050.pdf
CAMP Workshop, Kenya (November 1996) 1998. Gigasiphon macrosiphon. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.
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- Lovett, C.K. Ruffo, R.E. Gereau and J. R.D. Taplin, 2006. Field guide to the moist forest trees of Tanzania. Society for Environmental Exploration, London. Retrieved online (pdf) 5 April 2013 from http://www.cepf.net/Documents/Final_LovettRuffoGereau_FieldGuide.pdf
- Robertson, A. 1998. Gigasiphon macrosiphon - a Case of Mistaken Identity. Sea-Bean Newsletter: The Drifting Seed 4(1):7.
- Tropicos.org. Missouri Botanical Garden. Retrieved online 04 Apr 2013 from http://www.tropicos.org/Name/13051008.
- Verdcourt, B. 1982. Gigasiphon humblotianum (Leguminosae: Caesalpinioideae - Bauhinieae) as a drift seed. Kew Bulletin 36(4):659-660.