Fern  (Xiphopteris ascensionensis)

Xiphopteris ascensionensis is classified as Near Threatened (NT) on the IUCN Red List (1).

This small fern often grows as an epiphyte on bamboo trees (2). The fronds are short and bear small green leaflets that are tightly packed on the midrib of the frond (3).

Endemic to Ascension Island in the South Atlantic Xiphopteris ascensionensis is found on the more exposed side of the main mountain, known as Green Mountain (2).

This fern grows in association with mosses, often with Campylopus smaragdinus and Calymperes ascensionis (4). It is found either on moss-covered rocks or on bamboo trees (2), in the mist zone of the upper mountain (4).

Ferns are ‘primitive’ plants that spread by releasing spores rather than by producing flowers and fruits. The distinctive frond stage of the fern lifecycle is asexual; spores are released from the fronds, which then germinate into minuscule heart-shaped structures known as ‘prothalli’. It is here that the sexual stage of the lifecycle occurs; male and female organs on the prothallus produce sperm and eggs respectively. If the female eggs are fertilised successfully, a new fern plant will begin to grow and the cycle starts again (5).

Although the population of Xiphopteris ascensionensis appears to be relatively stable at present it may face long-term threats from the spread of introduced moss species such as Alpinia zerumbet, with which it appears unable to grow (2).

The population of Xiphopteris ascensionensis is being monitored by Ascension Conservation (2).