Vachellia anegadensis (Britton) Seigler & Ebinger

Kew Species Profiles

General Description

Few trees are under greater threat from increases in sea level due to climate change than poke-me-boy, found almost exclusively on one of the British Virgin Islands (Anegada), which stands only 8 m above the Caribbean Sea.

Until recently, Vachellia anegadensis was known only from Anegada, a low-lying coral limestone island (sometimes called the 'drowned island') in the British Virgin Islands (BVI). These Caribbean islands comprise one of the UK Overseas Territories (UKOTs). Taken overall, they are rich in plant diversity, with over 700 native species, but those species which occur only on a single island are particularly threatened by the potential effects of climate change, as they may have very specific habitat requirements. In 2008, one of Kew's botanists, Colin Clubbe, discovered a small population of poke-me-boy growing on Fallen Jerusalem, another of the BVI, where environmental conditions are different from those on Anegada. In 2005, some species of the genus Acacia were transferred to the genus Vachellia Wight & Arn., including V. anegadensis.

Species Profile

Geography and distribution

Acacia anegadensis occurs only in the British Virgin Islands in the Caribbean.

Kew's work in the British Virgin Islands

Kew has had connections with the BVI since the early years of the 20th century, when Kew gardener Walter Fishlock became an agricultural instructor on Tortola. During his time in the BVI he accompanied the American botanist, Nathaniel Britton, on a plant-collecting expedition to Anegada, during which Acacia anegadensis was discovered. Britton named the species after the island where it was found (and later named a genus Fishlockia after him for this species).

More recently, conservationists from Kew's UK Overseas Territories team have carried out intensive botanical studies on Anegada during the course of a project to assess the coastal biodiversity of the island and develop an action plan for its protection. Kew botanists are collaborating on a field guide to the islands' plants, as well as continuing fieldwork throughout BVI to support the BVI National Parks Trust and other local partners.

Description

Acacia anegadensis is an extremely spiny shrub or small tree, hence its local name of poke-me-boy. Its leaves are divided into up to four pairs of small leaflets. Clusters of tiny flowers form vivid yellow pompoms. Its curved pods (fruits) are typical of the legume family (the peas and beans), and split open, releasing the seeds.

Threats and conservation

According to IUCN Red List criteria, Acacia anegadensis is considered to be Critically Endangered, because it lives in a very small area (less than 10 km²), much of which is under threat from housing and hotel developments. It could also face difficulties if sea levels around Anegada rise as a result of global climate change, both from further reductions in the area of suitable habitat and from inundation with salt water. Invasive plants on the island, such as Casuarina equisetifolia , could also overwhelm the tree and its habitat.

The discovery of additional specimens of poke-me-boy on Fallen Jerusalem is cause for optimism, as this island is volcanic in origin and rises to a greater height above sea level than Anegada. Although it is even smaller in size than Anegada, Fallen Jerusalem is already a National Park where building is forbidden.

Acacia anegadensis is in cultivation in the J R O'Neal Botanic Garden on Tortola, the largest island in the BVI. It is also being grown in the nursery glasshouses at Kew. Seeds collected from trees in the wild are in safe storage in Kew's Millennium Seed Bank.

Uses

Although poke-me-boy is not currently used by islanders, reports in the older literature suggest that it was formerly cut for timber, and resin extracted from the tree was used to seal the hulls and decking of boats.

Millennium Seed Bank: Seed storage

Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.

This species at Kew

Acacia anegadensis is currently grown in Kew's behind-the-scenes nursery glasshouses where horticulturists are investigating the best environmental conditions for its cultivation.

Pressed and dried specimens of poke-me-boy, including some collected by Kew gardener Walter Fishlock, are held in Kew's Herbarium, where they are available to researchers by appointment.

Distribution

British Virgin Islands

Ecology

Most commonly on limestone rocks that form most of the land surface of eastern Anegada.

Conservation

Critically Endangered (CR) according to IUCN Red List criteria.

Hazards

No known health hazards, but difficult to handle due to its spines.

Use

Timber.