St Helena ebony (Trochetiopsis ebenus)
|Size||Height: up to 4 - 5 m (2)|
Classified as Critically Endangered (CR) on the IUCN Red List (3).
Only two individuals of this small tree still survive in the wild (4). Previously, the trees reached up to five metres tall but specimens today are low bushes with long branches spreading along the ground (2). The name ebony is derived from the hard, black wood. The tapering, heart-shaped leaves are dark green, with a soft downy underside (2). The flower stalk (inflorescence) bears up to three large white flowers, which may fade to pink as they age (2), and the angular seeds are a dark greyish-brown (2).
Endemic to St Helena in the southern Atlantic Ocean this species was once widespread in dryer parts of the north and west of the island at elevations between 200 and 500 metres above sea level (2). The ebony has suffered a devastating decline since the early 16th Century, and was feared to be extinct until two plants were discovered in 1980 on an inaccessible cliff between rock formations known locally as 'Lot's Wife' and the 'Asses Ears' (4).
The two remaining plants are found on a cliff (4).
The luxuriant flowers of the St Helena ebony may appear year round if rainfall is sufficient; however, the main flowering season runs from June to August (2). This species is fairly drought resistant and during long periods of dry weather the leaves begin to shrivel but quickly recover following rain (4).
The native flora and fauna of St Helena have suffered centuries of exploitation and many of the endemic and unique species have been lost. The most striking example of the devastation that has occurred is an area known as the Crown Wastes, a barren ground that has suffered massive erosion and covers 60 percent of the island (5). The St Helena ebony was once common in this area, which stands as a pertinent warning of the effects of over-exploitation. Goats were introduced to the island in the early 16th Century in order to provide food for sailors passing through the area (4). Vast herds of wild goats roamed the island and fed on native plants such as the ebony; the low branches of this species made it highly accessible and seedlings were particularly vulnerable, thus preventing population growth (4).
The St Helena ebony has proven easy to propagate and cuttings taken from the two remaining wild shrubs have been used to cultivate plants as part of the conservation programme for this species (4). Wild goats have been all but removed from the island following a concerted campaign in the 1960s (4). The ebony has been established in cultivation at two key sites: behind High Peak (not formerly within the range of the ebony) and Ebony Plain, although limited regeneration has been observed at either site (3). There are currently around 2000 individuals (3) but these were all derived from the two remaining plants, and subsequently have little genetic variation (4). At both sites the Ebony is planted with the hybrid, Trochetiopsis x benjaminii Cronk, also known as ‘Rebony’, and introgression is a possible threat (3). Smaller collections have been established at Scotland, Pounceys and White’s Cottage (Norman Williams Nature Reserve); in the latter two sites the hybrid is also planted (3). In addition, the ebony is also in cultivation in private gardens, usually derived from clonal material of the upper cliff plant (3). These cultivated populations are a mere shadow of the former glory of this species.
For more information on St Helena see:
- St Helena National Trust:
- UK Overseas Territories Conservation Forum (UKOTCF):
- Joint Nature Conservation Committee:
Authenticated (30/6/03) by Rebecca Cairns-Wicks. Chair, IUCN SSC South Atlantic Island Plant Specialist Group.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Inflorescence: the reproductive shoot of the plant, which bears flowers (See <link>http://www.rbgkew.org.uk/ksheets/pdfs/flower.pdf</link> for a fact sheet on flower structure)
- Introgression: when genes from one species are incorporated into the gene pool of another.
IUCN Red List (September, 2008)
- Cronk, Q.C.B. (2000) The Endemic Flora of St Helena. Anthony Nelson, Shropshire.
- Cairns-Wicks, R. (2003) Pers. comm.
- Cronk, Q.C.B. (1986) The Decline of the St Helena Ebony, Trochetiopsis melanoxylong. Biological Conservation, 35: 159 - 170.
- Cairns-Wicks, R. (2002) Saving the Remarkable Endemic Flora of St Helena. Plant Talk, 27: 29 - 34.