Snowdonia hawkweed (Hieracium snowdoniense)
|Also known as:||Heboglys Eryri|
|Size||Height: up to 30 cm (2)|
Although not yet assessed by the IUCN, this species is 'Critically Endangered' under IUCN threat criteria (3). It is a British Red Data Book species (4).
The Snowdonia hawkweed is one of the world's rarest plants with just one surviving specimen known. Amazingly, it was rediscovered in 2002 after a 35-year period when it was thought to be extinct (2). This hawkweed forms a rosette of gently toothed lance-shaped leaves which narrow towards the base to form a shaggy stalk. A slender stem bears a cluster of deep golden-yellow flower heads. The bases of the flower heads are surrounded by a whorl of black, velvety bracts (modified leaves), known as an 'involucre' (3).
Endemic to Wales, this hawkweed was first discovered in 1892; it is possible that this plant has always been rare (3), and it has only ever been recorded from seven mountain ledges in Snowdonia. It was previously last seen in 1967 in Cwm Idwal National Nature Reserve, but was rediscovered in July 2002 close to the last site following exhaustive searches by a team of botanists from the National Museums and Galleries of Wales and the Countryside Council for Wales (2).
The single known plant grows on a rocky, steep, and north-facing inaccessible mountain cliff. This hawkweed has historically been found growing at altitudes of between 300 and 900 m above sea level (3).
Snowdonia hawkweed was first described in 1892 and was given species status in 1955 by Peter Sell and Cyril West, both experts on hawkweeds. It is not clear if the newly discovered plant has been growing for many years or if it has re-emerged from buried seed (2). There is currently very little known of the ecology of this plant. Like all hawkweeds, the Snowdonia hawkweed is a perennial plant which may fruit irregularly. It flowers in July, reproduces asexually (without fertilisation), and produces wind-dispersed seeds which become ripe around 1 month after flowering (3).
The decline of this species may have been the result of a prolonged period of overgrazing, particularly the massive increase in sheep grazing in the Welsh mountains during the last 50 years. Sheep find many species of hawkweed extremely palatable, and in accessible areas they may have grazed Snowdonia hawkweed to extinction. An alternative explanation has been proposed for the extremely precarious status of this plant, namely the increase in acid rain, which is likely to have caused soil acidification (3). As this hawkweed is now so exceptionally rare, collection by botanists may be a new and potentially disastrous problem. Chance events such as rock-falls may also pose a risk to this hawkweed; as there is just one known remaining plant, the species is inherently more vulnerable to such unpredictable occurrences (3).
The current location and all historic sites for this hawkweed are afforded a high degree of protection as they are Sites of Special Scientific Interest (SSSIs), and occur in the Snowdonia National Park and the Yryri Special Area of Conservation (3). Encouragingly, sheep grazing has recently been eliminated from Cwm Idwal National Nature Reserve in order to aid the local wildlife; hopes are that this move will help the Snowdonia hawkweed to recover (2). Furthermore, seed has been collected in order to start an ex-situ population at the National Botanic Garden of Wales; seedlings are being cultivated at present. Further survey work has been proposed, which will aim to discover further wild plants, and, if establishment of a strong ex-situ population is successful, a re-stocking programme may be feasible (3). These urgent conservation measures aim to reclaim this acutely endangered and unique plant from the very brink of extinction.
For more on the National Museums and Galleries of Wales see:
Visit the Countryside Council for Wales website at:
Information authenticated by Tim Rich of the National Museums and Galleries of Wales.
- Ex-situ: measures to conserve a species or habitat that occur outside of the natural range of the species. E.g. in zoos or botanical gardens.
- Asexually: of asexual reproduction: reproduction that does not involve the formation of sex cells ('gametes'). In many species, asexual reproduction can occur by fission (or in plants 'vegetative reproduction'); part of the organism breaks away and develops into a separate individual. Some animals, including vertebrates can develop from unfertilised eggs, this process, known as parthenogenesis gives rise to offspring that are genetically identical to the parent.
- Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
- Perennial: plants that live for at least three seasons; after an initial period they produce flowers once a year.
- Whorl: in animals, the spiral or convolutions in the shell of a snail. In plants, a set of leaves, flowers, or branches that spring from a stem at the same point and encircle it.
- National Biodiversity Network Species Dictionary (February 2001) http://www.nhm.ac.uk/nbn/
- Rich, T. C. G (2002) Extinct plant rediscovered in Wales. Biodiversity News. 21: 4.
- Rich, T.C.G. & Hand, S.O. (2003) Conservation of Britain's biodiversity: Hieracium snowdoniense (Asteraceae), Snowdonia Hawkweed. Watsonia (in press).
- Wiggington, M. J. (1999) British Red Data Books 1: Vascular Plants. 3rd Edition. Joint Nature Conservation Committee, Peterborough.