Hedlundia minima, commonly known as the least whitebeam or lesser whitebeam (Welsh: cerddinen wen fach), is a deciduous shrub in the rose family (Rosaceae). It is a member of the genus Hedlundia, which comprises species of hybrid origin arising from crosses between members of the genus Aria (whitebeams) and Sorbus (rowans).
Taxonomy and Description
The species was first described by Augustin Ley in 1895 as Pyrus minima. It was later transferred to Sorbus as Sorbus minima (Ley) Hedl., and in 2017 it was reclassified under the newly erected genus Hedlundia by Sennikov and Kurtto. The current accepted binomial is Hedlundia minima (Ley) Sennikov & Kurtto.
Hedlundia minima is an apomictic triploid microspecies that reproduces asexually. It is believed to have originated as a hybrid between the rock whitebeam (Aria rupicola) and the rowan (Sorbus aucuparia).
It is a slender, deciduous shrub reaching up to 3 metres (approximately 10 feet) in height. The leaves are simple, elliptic to oblong-elliptic, 6–8 cm long and about half as wide, with 7–10 (usually 8 or 9) pairs of lateral veins. The leaves are lobed one-fifth to one-third of the way to the midrib, sharply serrated, dull green and glabrous above at maturity, and grey-tomentose beneath. The petiole is about 1.2 cm long. Flowers are white, with petals about 4 mm long, produced in May and June. The fruit (berries) are red, globose to oblate, 6–8 mm across, with few small lenticels.
Distribution
Hedlundia minima is endemic to Wales, United Kingdom. It grows exclusively on Carboniferous Limestone cliffs in the traditional county of Breconshire (modern Powys), on the northern edge of Mynydd Llangatwg in the Brecon Beacons National Park. The largest population is at Craig y Cilau National Nature Reserve, where 730 plants were counted in September 2002. Smaller populations occur at Cwm Cleisfer, and a single plant remains at Craig y Castell. It formerly occurred at Blaen Onneu.
Conservation Status
The species is listed as Vulnerable on the IUCN Red List. Fewer than 350 specimens are estimated to remain in the wild. In 1947, the species was threatened by British Army mortar practice in and around its habitat; Labour MP Tudor Watkins raised the issue in the House of Commons, leading War Secretary Frederick Bellenger to order the Army to withdraw from the area, an action credited with preserving the species from extinction. Quarrying has also destroyed many plants and reduced available habitat. All locations where the species grows, except Cwm Cleisfer, now have some form of protection, and a population is maintained at the National Botanic Garden of Wales.
