Flora of St Helena
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The flora of Saint Helena, an isolated island in the South Atlantic Ocean, is exceptional in its high level of endemism and the severe threats facing the survival of the flora.[1] In phytogeography, it is in the phytochorion St. Helena and Ascension Region of the African Subkingdom, in the Paleotropical Kingdom.
Endemic and introduced flora[]
The endemic plants of Saint Helena include many notable Cabbage Tree or, "insular arborescent Asteraceae", members of the daisy family which have evolved a shrubby or tree-like habit on islands. Other notable endemics include the closely related St Helena redwood (Trochetiopsis erythroxylon) and St Helena dwarf ebony (Trochetiopsis ebenus). These are unrelated to the redwood trees of California or to the ebony trees of commerce, being instead in the Mallow family (Malvaceae).
Vegetation[]
Today there are three major vegetation zones: the tree-fern thicket of the highest parts of the central ridge; the pastures of middle elevations and the dry, eroded "crown wastes" of lower elevations. Of these only the tree-fern thicket is a natural vegetation type. The middle elevations were formerly covered with native woodland of gumwoods (Commidendrum) and other trees, now largely destroyed. The "Crown wastes" or coastal zones were formerly covered with native scrub, of which a major component was probably St Helena dwarf ebony (Trochetiopsis ebenus and St Helena tree ebony Trochetiopsis melanoxylon).
Human impact and conservation[]
The destruction of the native vegetation began soon after the discovery of the island by the Portuguese in 1502, with the introduction of goats. As there were no native herbivorous mammals, the flora was unadapted to such threats. Later with the establishment of permanent settlement on the island by the English East India Company in 1659, many introduced plants became established which created new vegetation types. Furthermore the native trees were subject to catastrophic cutting for such purposes as housebuilding and to fuel stills for the distillation of arrack. As a result of this legacy many endemic plant species are extinct or critically endangered.
Endemic vascular plants of St Helena[]
Monocotyledons
- Bulbostylis lichtensteiniana (Kunth) C.B. Clarke
- Bulbostylis neglecta (Hemsl.) C.B. Clarke
- Steud.
- Boott
- Hemsl.
Dicotyledons
- Acalypha rubrinervis Cronk
- Aellen
- Commidendrum robustum (Roxb.) DC. ssp. robustum
- Commidendrum robustum (Roxb.) DC. ssp. gummiferum (Roxb.) Cronk
- Commidendrum rotundifolium (Roxb.) DC.
- Commidendrum rugosum (Aiton) DC.
- Commidendrum spurium (G. Forst.) DC.
- Euphorbia heleniana Thell. & Stapf
- Frankenia portulacifolia (Roxb.) Spreng.
- Heliotropium pannifolium Burch. ex Hemsl.
- (Hook.f.) N.E.Br.
- (Hook.f.) K. Müll.
- Lachanodes arborea (Roxb.) B. Nord.
- Melanodendron integrifolium (Roxb.) DC.
- Mellissia begoniifolia (Roxb.) Hook.f.
- Nesiota elliptica (Roxb.) Hook.f.
- Nesohedyotis arborea (Roxb.) Bremek.
- Norl.
- Pelargonium cotyledonis (L.) L'Hér.
- Petrobium arboreum (J.R. & G. Forst.) R. Br.
- Phylica polifolia (Vahl) Pillans
- Pladaroxylon leucadendron ( G. Forst.) Hook.f.
- Plantago robusta Roxb.
- Sium bracteatum (Roxb.) Cronk
- Sium burchellii (Hook.f.) Hemsl.
- Suaeda fruticosa Forssk. ex J.F. Gmel.
- Trimeris scaevolifolia (Roxb.) Mabb.
- Trochetiopsis ebenus Cronk
- Trochetiopsis erythroxylon (G. Forst.) Marais
- Trochetiopsis melanoxylon (Sol. ex Sims) Marais
- Cronk
- Wahlenbergia angustifolia (Roxb.) A.DC.
- A.DC. in DC.
- Wahlenbergia linifolia (Roxb.) A.DC.
- Wahlenbergia roxburghii A.DC.
Pteridophytes (Ferns and fern-allies)
- Sw.
- Kunze ex Mett.
- (Hook.) Cronk
- Dicksonia arborescens L'Hér.
- (Roxb.) Cronk
- Dryopteris cognata (C. Presl) Kuntze
- (Bory) Kuntze
- Elaphoglossum dimorphum (Hook. & Grev.) Moore
- Elaphoglossum nervosum (Bory) H.Christ
- (Maxon) Tardieu
- Roxb.
- Roxb.
- (L.f.) Fée
- A. Braun
- (Hook.) Holttum
- Roxb.
Endemic genera[]
See also[]
References[]
- ^ Quentin Cronk (2000). Endemic Flora of St Helena. Anthony Nelson.
External links[]
- Plant talk article: The Millennium Forest: evolving and maturing
- A potted history of the flora of St Helena and its conservation
Sources[]
- Melliss, John Charles (1875). St Helena. Reeve, London.
Further reading[]
- Philip and Myrtle Ashmole (2000). The natural history of St Helena and Ascension Island. Oswestry: Anthony Nelson Ltd.
- Quentin Cronk (2000). The endemic flora of St Helena. Oswestry: Anthony Nelson Ltd.
- Flora of Saint Helena
- Biota of Saint Helena
- Lists of plants
- Paleotropical flora