Cycas tansachana


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Cycas tansachana
Species Authority: K.D.Hill & S.L.Yang

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2cd; B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) ver 3.1
Year Published: 2010
Date Assessed: 2009-10-31
Assessor(s): Hill, K.D.
Reviewer(s): Donaldson, J.S. & Bösenberg, J.D.
This species has an extremely small area of occupancy and extent of occurrence (less than 10 km²), is known only from a single location and has declined dramatically due to mining of limestone for the making of cement. At one stage it was thought to be Extinct in the Wild after limestone outcrops were destroyed, but was subsequently found on adjacent outcrops.
2003 Critically Endangered (IUCN 2003)
2003 Critically Endangered

Geographic Range [top]

Range Description:This species is endemic to south central Thailand, occurring to the north east of Khong Khi Sua in Sariburi Province. Occurs at an elevation of 400 m.
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: Plants are locally abundant (2,500 to 10,000 mature individuals) but very restricted in their distribution.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This species grows on limestone outcrops growing in full sun or partial shade in crevices on bare rock. The limestone outcrops are covered with sparse, seasonally deciduous forest.
Systems: Terrestrial

Threats [top]

Major Threat(s): This species is apparently quite restricted in occurrence and under severe pressure from plant collectors and limestone mining operations.

Conservation Actions [top]

Conservation Actions: This species is listed on Appendix II of the CITES Appendices.

Bibliography [top]

Hill, K.D. and Stevenson, D.W. 1998 - 2006. The Cycad Pages. Available at:

Hill, K.D. and Yang, S.-L. 1999. The genus Cycas (Cycadaceae) in Thailand. Brittonia 51(1): 48-73.

IUCN. 2010. IUCN Red List of Threatened Species (ver. 2010.3). Available at: (Accessed: 2 September 2010).

Jones, D.L. 2002. Cycads of the World. Smithsonian Institution Press, Washington, DC.

Whitelock, L.M. 2002. The Cycads. Timber Press, Portland, Oregon.

Citation: Hill, K.D. 2010. Cycas tansachana. In: The IUCN Red List of Threatened Species. Version 2014.3. <>. Downloaded on 29 March 2015.
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