|Scientific Name:||Trochetiopsis ebenus Cronk|
Melhania melanoxylon sensu Melliss non R.Br.
Trochetiopsis melanoxylon (R.Br. ) Marais non Cronk
|Red List Category & Criteria:||Critically Endangered D ver 3.1|
|Assessor(s):||Lambdon, P.W. & Ellick, S.|
Although Dwarf Ebonies (Trochetiopsis ebenus
|Previously published Red List assessments:|
|Range Description:||The Dwarf Ebony is found in the wild only at 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 100 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 only extant site is a phonolytic cliff on the eastern side of Blue Point Ridge. The bluff is now sometimes known as ‘Ebony Point’.
There is very little evidence from which the original range can be reconstructed. The only previous wild localities which can certainly be attributed to this species were noted by W.J. Burchell in the early 19th Century, at High Hill and Man & Horse. These two historical and the modern site lie within a 2 km radius in the south-western part of St Helena, between 500 and 700 m altitude. Other locations mentioned in 18th Century references (e.g. High Knoll, The Barn) would extend the range across drier coastal hills over almost the entire island, but it is unclear whether these early records refer to T. ebenus or T. melanoxylon.
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:||The current wild population numbers just two mature individuals and three juveniles. The juveniles may have self-seeded since 1980, when the site was discovered by George and Charlie Benjamin and Quentin Cronk (see Cronk 2000). Prior to this, the species was thought to have been extinct since 1850, when a garden plant was noted at Oakbank by J.C. Melliss (Melliss 1875).|
|Current Population Trend:||Stable|
|Habitat and Ecology:|
Known locations suggest that the Dwarf Ebony is a species of arid coastal hill tops. It is resilient to dry conditions, but appears to be less tolerant of strong winds or prolonged drought than other endemic shrubs of St Helena’s dryland zone, e.g. Scrubwood (Commidendrum rugosum (Aiton). DC.), and fares better in sheltered locations with less arid soils, provided there is little competition from taller species.
|Continuing decline in area, extent and/or quality of habitat:||No|
|Movement patterns:||Not a Migrant|
|Use and Trade:||The Dwarf Ebony has recently been adopted as St Helena’s national flower and thus has symbolic and cultural value. It makes an excellent garden plant but has not yet been widely grown outside the island. Specimens propagated at the government plant nursery (now managed by the Environmental Conservation Section) have been made freely available to the public and plants are swapped by local gardeners. Thus, although popular as an ornamental, the commercial trade is minimal.|
The almost total annihilation of the species occurred before 1800, and as this pre-dates most of the botanical records of St Helena, there is little direct evidence to determine its cause. However, very high levels of goat grazing were very likely to have been a major factor. Goats (Capra hircus) were introduced by Portuguese sailors in the early 16th Century and thrived in large numbers until their virtual eradication in the 1950-70s. During the intervening period, much of the island’s native vegetation cover was lost from the mid-altitude hills. Other invasive herbivores such as rabbits (Oryctolagus cuniculus), rats (Rattus rattus and R. norvegicus) and mice may have had further impacts on seed and seedling regeneration.
Cuttings were collected from one plant at Ebony Point soon after the Dwarf Ebony was rediscovered in 1980, following a daring cliff descent on a rope and makeshift harness by Charlie Benjamin. In 2008, further collections were made from the second plant by Mike Thorsen. The species also grows well from seed, and has now been propagated very successfully. Today, there are a few thousand specimens on St Helena, mostly in gardens and at sites where attempts have been made to restore the species to wild situations. The main reintroduction sites include Ebony Plain (approximately 840 surviving plants), High Peak (130 plants) and the Millennium Forest (several hundred).
Antommarchi, F.C. 1825. Esquisse de la flore de Sainte Hélène. Barrois l’Aine, Paris.
Burchell, W.J. 1805-10. Flora Insulae Sanctae Helenae. Unpublished manuscript held at Royal Botanic Gardens Kew, Richmond, U.K.
Cairns-Wicks, R. 2003. Trochetiopsis ebenus. The IUCN Red List of Threatened Species 2003: e.T37855A10082104. doi: /10.2305/IUCN.UK.2003.RLTS.T37855A10082104.en.
Cairns-Wicks, R. Draft Recovery Action Plan for Trochetiopsis ebenus (Sterculiaceae).
Cronk, Q.B.C. 1986. The decline of the St Helena ebony Trochetiopsis melanoxylon. Biological Conservation 35: 159-172.
Cronk, Q.B.C. 1995. A new species and hybrid in the St Helena endemic genus Trochetiopsis (Sterculiaceae). Edinburgh Journal of Botany 52: 205-213.
Cronk, Q.C.B. 2000. The Endemic Flora of St. Helena. Anthony Nelson Publishers, Oswestry, UK.
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.
Rowe, R. 1995. The population biology of Trochetiopsis: a genus endemic to St Helena. Unpublished PhD thesis, University of Oxford, Oxford, 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. Trochetiopsis ebenus. The IUCN Red List of Threatened Species 2016: e.T37855A67371855.Downloaded on 18 October 2017.|
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