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Hamadryas argentea

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Taxonomy [top]

Kingdom Phylum Class Order Family
PLANTAE TRACHEOPHYTA MAGNOLIOPSIDA RANUNCULALES RANUNCULACEAE

Scientific Name: Hamadryas argentea
Species Authority: Hook.f.
Common Name(s):
English Silvery Buttercup

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2012
Date Assessed: 2012-04-16
Assessor(s): Upson, R., McAdam, J.H., Clubbe, C.P. & Lewis, R.
Reviewer(s): Hilton-Taylor, C. & Bilz, M.
Contributor(s): Broughton, D.A.
Justification:

The Silvery Buttercup (Hamadryas argentea) has an extent of occurrence (EOO) of about 13,209 km² and an area of occupancy (AOO) of 192 km².  Subpopulation sizes are generally small and the population as a whole is severely fragmented. The distribution of this species suggests that there is a threat from grazing as it is limited to ungrazed sites or areas where grazing levels are reduced; this in turn suggests that there has been a decline in numbers of this species over time, however, it is not clear whether this decline is continuing or not. Hence the Silvery Buttercup is assessed as Near Threatened as it is close to qualifying for a threatened category under criteria B1a and B2a.

There appears to be a large amount of vegetative spread within subpopulations which makes estimation of the number of individuals difficult; some populations appear to consist of a single male and female plant which is merely spreading via rhizomes. If future genetic work shows that the majority of subpopulations comprise only several individuals, with extensive vegetative spread, this species may warrant a much more threatened status.

History:
2003 Near Threatened

Geographic Range [top]

Range Description: Endemic to the Falkland Islands. H. argentea is widespread but scarce across the islands, occurring in 25 ten km UTM grid squares.
Countries:
Native:
Falkland Islands (Malvinas)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

There is a large amount of vegetative spread within subpopulations which makes estimation of the number of individuals difficult; some populations appear to consist of a single male and female plant which is merely spreading via rhizomes. There are >2,000 leaf rosettes of H. argentea across the Falkland Islands, with the largest subpopulations composed of about 500 leaf rosettes.

The population as a whole is severely fragmented.
Population Trend: Unknown

Habitat and Ecology [top]

Habitat and Ecology: H. argentea grows predominantly where gazing pressure is low or absent: in maritime cliff and slope habitats, inland rock, Poa alopecurus acid grassland (upland), dwarf shrub heath, Fachine scrub, cushion heath (upland) and fern beds.
Systems: Terrestrial

Use and Trade [top]

Use and Trade: There is no known use.

Threats [top]

Major Threat(s): The distribution of this species suggests a threat from grazing as although not limited to ungrazed sites, where grazing occurs it is present as a highly reduced form that may rarely or never produce seed. The suppression of reproductive activity under grazing indicates that there has probably been a decline in numbers of this species over time.

Conservation Actions [top]

Conservation Actions:

Ex situ Conservation:

A seed collection is held at Kew's Millennium Seed Bank. Leaf material has been collected from several subpopulations and is held at the Royal Botanic Gardens Kew for future genetic research and DNA banking.

A plant is currently being propagated from vegetative material at Royal Botanic Gardens Kew and another plant cultivated from vegetative material is growing in Falkland Conservation's small botanical garden.


In situ Conservation:

Three Important Plant Areas have been identified which cover subpopulations of this species including the largest yet recorded (in terms of number of leaf rosettes) (Upson 2012).

The species occurs in a protected area.

A species identification guide is available for free download from Falkland Conservation's website.

Research Needed:
  • Genetic studies to estimate population size are required i.e. elucidating the degree of vegetative spread for a sub-set of subpopulations.

Citation: Upson, R., McAdam, J.H., Clubbe, C.P. & Lewis, R. 2012. Hamadryas argentea. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 30 September 2014.
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