Ptisana purpurascens
| Ptisana purpurascens | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Division: | Polypodiophyta |
| Class: | Polypodiopsida |
| Order: | Marattiales |
| Family: | Marattiaceae |
| Genus: | Ptisana |
| Species: | P. purpurascens
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| Binomial name | |
| Ptisana purpurascens | |
| Synonyms[2] | |
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Ptisana purpurascens is a species of fern in the family Marattiaceae that is endemic to Ascension Island. It is considered a critically endangered species.
Distribution and habitat[edit]
Endemic to central Ascension Island, P. purpurascens is known only from a single population on the upper slopes of Green Mountain at altitudes of 700–860 m (2,300–2,820 ft). The majority of the population can be found on the south and east facing slopes, with a few isolated plants growing on the south-west slopes or amongst a bamboo thicket near the summit. The total extent of this species is estimated to be approximately 12 ha (30 acres), with the area of occupancy estimated to be less than 4.5 ha (11 acres).[1][3]
Description[edit]
It has a globular rhizome with stipule-like fleshy outgrowths. The leaves are dark green, twice pinnate and up to 1 metre long. Every pinnule has up to six pairs of leaflets. The petioles are dark-purplish, hence the name 'purpurascens' meaning 'becoming purple'. The sporangia are fused in all Ptisana into a bivalvate synangium.
Conservation status[edit]
Conservation plans have been proposed for Ptisana purpurascens, an endemic of the distant in the South Atlantic, where a single population remains on Green Mountain. While the mature plants are still present in large numbers, long-term threats to its survival exist in the form of competition with alien invasive species like introduced plants such as Buddleja madagascariensis and grazing by sheep and rabbits. Successful reproduction is very rare, making the species highly endangered.
References[edit]
- ^ a b Niissalo, M.; Stroud, S.; Gray, A.; Lambdon, P.W.; Renshaw, O. (2012). "Ptisana purpurascens". IUCN Red List of Threatened Species. 2012: e.T43922A2990240. doi:10.2305/IUCN.UK.2012-1.RLTS.T43922A2990240.en. Retrieved 22 May 2024.
- ^ "Ptisana purpurascens (de Vriese) Murdock". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 22 May 2024.
- ^ Ascension Island Government (2015). "Ptisana purpurascens species action plan" (PDF). Ascension Island Government Conservation Department. Retrieved 22 May 2024.
 | This article includes a list of general references, but it lacks sufficient corresponding inline citations. (March 2011) |
- Gray, A., Palembe, T., Stroud, S. 2005. The conservation of the endemic vascular flora of Ascension Island and threats from alien species. Oryx 39: 449–453. [1]
- See the ARKive site for additional information [2]
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