St. Helena olive tree
| St. Helena olive tree | ||||||||||||
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St. Helena olive tree ( Nesiota elliptica ), illustration |
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| ( Roxb. ) Hook.f. |
The St. Helena olive tree ( Nesiota elliptica ) was the only species of the monotypic genus Nesiota . Despite the name, it was not closely related to the olive tree , but belonged to the buckthorn family (Rhamnaceae). It was endemic to the highest points of the eastern central mountain range of the island of St. Helena and has been considered extinct since 2003 .
description
The St. Helena olive tree was a small tree that reached heights of up to four meters, with numerous branches and a dark brown to black bark. The wrongly elongated leaves with a curled tip were 5 to 8 inches long and 2 to 3.5 inches wide. The top of the leaves was dark green and the light underside was covered with flat-lying hairs.
The tightly clustered , light pink flowers grew in a branched inflorescence that did not protrude above the leaves. The flowering period was from June to October. The plant was 99% self-incompatible, that is, this species was unable to pollinate itself. The endemic fly species Sphaerophoria (Loveridgeana) beattiei acted as pollinators .
The fruits took a year to ripen. The hard, woody capsule fruits were one to two centimeters long and burst open when ripe, revealing triangular, glossy black seeds.
die out
The St. Helena olive tree was extremely rare as early as the 19th century. The decrease was probably due to habitat loss due to deforestation for timber production and overgrazing by feral domestic goats as well as fungal diseases . The botanist John Charles Melliss counted only twelve to fifteen trees in 1875; a short time later the species was thought to be lost until a single specimen was rediscovered on Diana's Peak in August 1977 . This tree was infected with numerous fungal infections which were made worse in attempts to preserve it. The last wild St. Helena olive tree died on October 11, 1994, but the "Environmental Conservation Section", St. Helena, succeeded in growing a two meter high tree from a branch. Before this specimen was received in 1997, four seedlings were grown in 1995 in the "Pounceys Arboretum". From 1999 only one survived. In December 2003 this specimen also died due to a fungal infection. Since then, the species has been considered extinct.
literature
- QCB Cronk: The endemic Flora of St Helena . Anthony Nelson Ltd, Oswestry 2000.
Web links
- ARKive - Pictures and information about Nesiota elliptica .
- Illustration of the St. Helena olive tree
- Nesiota elliptica in the endangered Red List species the IUCN 2011. Posted by: Cairns-Wicks, 2004. Accessed March 12, 2012th