|Scientific Name:||Commidendrum rotundifolium (Roxb.) DC.|
Psiadia rotundifolia (Roxb.) Hook.f.
Solidago rotundifolia Roxb.
|Red List Category & Criteria:||Critically Endangered D ver 3.1|
|Assessor(s):||Lambdon, P.W. & Ellick, S.|
|Contributor(s):||Darlow, A. & Cairns-Wicks, R.|
Given the extreme decline to a single individual, the Bastard Gumwood (Commidendrum rotundifolium
|Previously published Red List assessments:|
|Range Description:||The Bastard Gumwood is restricted to a single locality on the south-western coastal hills of St Helena, South Atlantic Ocean.|
The extent of occurrence (EOO), based on the area of a minimum convex polygon around known localities, is 13 m2. The area of occupancy (AOO), based on a 2 km × 2 km grid, is 4 km2. Following IUCN Red List Guidelines, the EOO is therefore increased to 4 km2 to match the AOO.
The world population is now represented by only one remaining wild tree, discovered in 2009 growing on a cliff at Botley’s Ley, 375 m altitude.
The Bastard Gumwood has been very rare since at least the mid 18th Century, before which the botanical history of St Helena was poorly known. However, since the few recorded localities are very widely scattered, it is likely that the distribution once encompassed much of the mid-altitude zone. In the late 19th Century, plants survived only at Longwood (the last individual died in 1897) and Horse Pasture (two individuals, but the precise locality was subsequently forgotten). Throughout much of the 20th Century the species was assumed to be extinct, but a single tree was rediscovered, also at Horse Pasture (perhaps one of the original individuals), in 1982. This tree died just four years later.
Native:Saint Helena, Ascension and Tristan da Cunha (Saint Helena (main island))
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Only one wild individual survives, though a small cultivated population is also in existence on St Helena.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
There is little information with which to reconstruct details of the ecology of this species. All known historical localities are between 350 and 450 m altitude, suggesting a preference for reasonably dry hill-slopes, perhaps in the transitional zone between the arid lowlands and the more heavily wooded uplands. Above 400 – 450 m, forests of the closely-related Gumwood (Commidendrum robustum (Roxb.) DC.) once dominated large areas.
|Movement patterns:||Not a Migrant|
|Use and Trade:||Was probably used as firewood and timber in the past.|
The presumed dramatic decline of the Bastard Gumwood is thought to have been largely attributable to very high grazing pressure from Goats (Capra hircus). Goats were introduced by Portuguese sailors in the early 16th Century, and flourished in large numbers until concerted control measures lead to their near eradication between the 1950s and 1970s. Across the dry, mid-altitude hills, much of the original native vegetation cover was lost during the intervening years. In the early days of the British colony, there was also a great demand for timber and firewood, and it is likely that a substantial number of trees were felled with little heed given to stewardship of such important resources. However, as the island was not settled for more than 150 years after the first Goats arrived, it is unclear how many trees survived into The Colonial Period. Later accounts indicate that the species was extremely rare by the mid 1700s.
Following the rediscovery of the Horse Pasture tree, seed was collected and several daughters were propagated (Cairns-Wicks 2009). By 2009 these had dwindled to a single individual located at Pouncey’s, which was in poor condition. Further propagation attempts had been unsuccessful because, although germination was found to be moderately good, all saplings proved to be of hybrid origin. The tree had crossed with False Gumwoods (C. spurium (G.Forst.) DC.), growing at a nearby nursery, to produce fertile offspring.
Ashmole, P. and Ashmole, M. 2000. St Helena and Ascension Island: a natural history. Anthony Nelson, Oswestry, U.K.
Burchell, W.J. 1805-10. Flora Insulae Sanctae Helenae. Unpublished manuscript held at Royal Botanic Gardens Kew, Richmond, U.K.
Cairns-Wicks, R. 2003. Commidendrum rotundifolium. The IUCN Red List of Threatened Species 2003: e.T37591A10060851. doi: /10.2305/IUCN.UK.2003.RLTS.T37591A10060851.en.
Cairns-Wicks, R. 2009. Draft Recovery Action Plan for Commidendrum rotundifolium (Compositae). Unpublished report to the St Helena National Trust, Jamestown, St Helena.
Cronk, Q.C.B. 2000. The Endemic Flora of St. Helena. Anthony Nelson Publishers, Oswestry, UK.
Eastwood, A. and Cronk, Q.C.B. 2002. Incompatibility and hybridisation in Commidendrum rotundifolium and C. spurium from St Helena: implications for ex situ management and species recovery. In: A. Eastwood. Evolution and Conservation of Commidendrum and Elaphoglossum from St Helena. Thesis for Doctor of Philosophy, University of Edinburgh.
Eastwood, A., Gibby, M. and Cronk, Q.B.C. 2004. Evolution of St Helena arborescent Astereae (Asteraceae): relationships of the genera Commidendrum and Melanodendron. Botanical Journal of the Linnean Society 144: 69–83.
IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-1. Available at: www.iucnredlist.org. (Accessed: 30 June 2016).
Lambdon, P. 2012. Flowering Plants and Ferns of St Helena. Pisces Publications, Newbury, UK.
Melliss, J.C. 1875. St Helena: A Physical, Historical and Topographical Description of the Island, Including its Geology, Fauna, Flora and Meteorology. L. Reeve & Co., London, U.K.
Royal Botanic Gardens, Kew. 2009. Data extracted from notes accompanying collection of herbarium specimens. Accessed 2009. Royal Botanic Gardens, Kew, London.
|Citation:||Lambdon, P.W. & Ellick, S. 2016. Commidendrum rotundifolium. The IUCN Red List of Threatened Species 2016: e.T37591A67370300.Downloaded on 21 September 2017.|