|Scientific Name:||Sium burchellii|
|Species Authority:||(Hook.f.) Hemsl.|
|Taxonomic Notes:||Endemic. Very close to S. bracteatum which was formerly considered by some Botanists to be a variant of Sium burchelli, but growth habit and fruit clearly distinguish the two species (Cronk 2000). Cronk also remarks (Cronk 2000) that the two Sium species kept their distinctive characteristics when grown side by side from seed in the Temperate House at the Royal Botanic Gardens, Kew. Hybridisation is suspected but not confirmed and further study is needed.|
|Red List Category & Criteria:||Endangered D ver 3.1|
|Reviewer/s:||Cronk, Q. & Clubbe, C. (South Atlantic Island Plants Red List Authority)|
More information is needed for this species regarding subpopulation sizes and regular monitoring to determine status of subpopulations. In particular because of decrease in quality of habitat at High Peak and elsewhere through competition from alien species. Subpopulation sizes are small < 50 individuals and severely fragmented.
|Range Description:||A rare plant, local around High Peak c 750 m. Restricted to small and fragmented subpopulations on steep cliffs just below the crest of the ridge, on the windward side of the central ridge only. Known to grow on the cliff below path leading to Cuckhold’s Point (the Landslide in Peaks Management Plan), Washhouse Cliff (WASH003 in Peaks Management Plan), Purgatory, and at High Peak. Cronk also records it between Red Rock and the Depot and in small patches on the cliff of Sandy Bay Ridge facing Rose Cottage (no observations have been made at these sites in the last 10 years). Subpopulation sizes are small <50 individuals and severely fragmented.|
Native:Saint Helena, Ascension and Tristan da Cunha
|Range Map:||Click here to open the map viewer and explore range.|
|Habitat and Ecology:||Rocky cliffs and ledges on the Peaks, amongst Cabbage trees, tree ferns or exposed ledges. Flowering is usually December and January.|
Competition from introduced and naturalized plants posses a threat for this species, particularly at High Peak where there is no regular management programme. All subpopulations have been found growing on rocky outcrops that are prone to landslides.
S. burchelli is thought to be under threat from hybridization with S. bracteatum. During November 1995, 800 Dwarf Jellico seedlings were planted across the tree fern thicket at several sites along the ridge between Cuckhold’s Point and Mt Actaeon within Diana’s Peak National Park. A high rate of establishment was recorded (36 out of 50 at one site) in April 1996 (Smith and Williams 1996), however, some of the individuals were planted relatively close to stands of the Large Jellico and it is suspected that the two species are able to hybridize, and the provenance of the Dwarf Jellico’s planted in 1995 is now uncertain.
|Conservation Actions:||Protected under the Endangered Endemic and Indigenous Species Protection Ordinance No 7 of 1996. Also protected within the Diana’s Peak National Park which is has been managed under a management plan since 1996 (Smith and Williams 1996), although its still lacks specific legislation the 1998/1999 revision of the SLUP (1993) provides for the protection of the National Park. A seed orchard was established at the Environmental Conservation Section Nursery in Scotland in 1997, but this has subsequently been allowed to deteriorate. It is recommended that this is re-established to bring together the genetic diversity represented in the subpopulations and allow seed collection for further reintroductions.|
|Citation:||Cairns-Wicks, R. 2003. Sium burchellii. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 08 December 2013.|
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