Anogramma ascensionis (Ascension Island parsley fern)
Clinging to an unstable cliff on a sharp mountain ridge, four tiny plants of the Ascension Island parsley fern, thought to be extinct for over 50 years, were discovered by conservation biologists in 2009.
About this species
When he visited Ascension in 1843, the botanist Joseph Hooker (later to become the director of the Royal Botanic Gardens, Kew) discovered the tiny Ascension Island parsley fern and sent herbarium specimens back to Kew. Although relatively common in Hooker’s time, the fern decreased dramatically in numbers until the late 1950s. After that, botanists thought that it had become extinct since it could not be found in any areas that provided suitable habitat. When a small population of the fern was rediscovered in 2009, botanists and conservationists made a concerted effort to care for the wild plants until they produced spores and could be brought into cultivation, both on the island and at Kew.
Geography & Distribution
The Ascension Island parsley fern occurs only on Ascension, a volcanic island in the middle of the Atlantic Ocean, just south of the Equator. Ascension is one of the UK’s Overseas Territories.
As its name implies, the Ascension Island parsley fern in its spore-producing form resembles a miniature parsley plant. When he discovered the plant in 1843, Joseph Hooker described the fronds as ‘brittle, glistening, pale but bright yellow-green when fresh’. Like all ferns, the Ascension Island parsley fern has two generations, one (the sporophyte) producing spores which then germinate, giving rise to sporelings (the gametophyte generation), small green structures with separate male and female organs.
Threats & Conservation
Anogramma ascensionis gametophytes in culture (Image: Andrew McRobb)
The Ascension Island parsley fern was believed to be extinct for over 50 years, until a very small colony was rediscovered in 2009. The fern grows on unstable cliff faces where shifting rocks can threaten the plants. It also faces severe competition from an invasive introduced maidenhair fern (Adiantum sp.) which is encroaching on suitable rocky ledges.
Conservationists on the island tended the rediscovered plants, clambering carefully down the rocky ridge to water them and remove weeds. Once the plants began to produce spores, the Ascension conservation team collected them as quickly as possible. With the assistance of the Island’s Administrator, the spores were despatched to Kew. Less than 24 hours after they had been harvested on Ascension they had reached Kew’s Conservation Biotechnology Unit (CBU) and been transferred into sterile culture. The spores were sterilised to remove surface contaminants and grown on a defined culture medium under sterile conditions to promote the development of gametophytes. The gametophytes that developed from the spores were transferred to a multiplication medium to increase the stock. These stock cultures were used to generate sporophytes and used in preliminary cryopreservation studies. More sporophytes were grown and transferred to a maintenance medium until fully grown and ready for transferring to the glasshouse. 90% of the sporophytes transferred to the glasshouse have survived and have produced new fronds. Currently the CBU team is developing methods to store the gametophytes in liquid nitrogen for long-term storage. Spores have also been germinated on Ascension and grown on to produce gametophytes which have gone on to produce sporophytes.
Ascension Island parsley fern at Kew
All Kew’s living specimens of the Ascension Island parsley fern are held behind-the-scenes in the Conservation Biotechnology Unit or fern nurseries for safe-keeping.
Kew's work on Ascension Island
Ascension Island conservationist monitoring the Ascension Island parsley fern site (Image: Marcella Corcoran, RBG Kew)
Kew has had a long involvement with Ascension Island and Kew’s UK Overseas Territories team is actively collaborating with Ascension conservationists on various projects. Of the island’s ten known endemic plants, i.e. those that live nowhere else on Earth, three are already extinct and little of the island’s original vegetation remains. As well as contributing to a project monitoring the invasive plants which threaten surviving endemics, Kew is supporting the development of propagation and horticultural facilities on Ascension, so that the number of endemic plants in cultivation can be increased. Other endemic species now in cultivation include two Critically Endangered ones - the fern Pteris adscensionis and the Ascension spurge (Euphorbia origanoides). These plants are being reintroduced to the wild whenever suitable sites can be cleared of invasive weeds.
Herbarium specimen showing Anogramma ascensionis ferns collected by Sir Joseph Hooker in 1843 (Image: RBG Kew)
Press release: Ascension Island’s ‘extinct’ parsley fern makes a dramatic reappearance during International Year of Biodiversity
Learn more about developing Ex Situ Conservation Collections of UKOTs Species In-Territory and at Kew Ascension Island on-line herbarium
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