101 CONSERVATION OF HIERACIUM ASTERIDIOPHYLLUM AND H. CILLENSE Conservation of Britain’s biodiversity: Hieracium asteridiophyllum and H. cillense (Asteraceae)

Hieracium cillense and H. asteridiophyllum are very rare endemic Welsh hawkweeds confined to limestone cliffs in and around Craig y Cilau National Nature Reserve, Llangattock, Brecon (v.c. 42). In June 2000 surveys were carried out of their entire populations to assess their requirements for conservation. 659 plants of H. cillense were found; 396 plants in the N.N.R., and 263 in a new extension of the population to the east. 512 plants of H. asteridiophyllum were found; 296 plants in the N.N.R., and 216 mostly in a new extension of the population to the east. Compared with population sizes in the N.N.R. in 1975, more plants of H. cillense were found and fewer of H. asteridiophyllum; the differences are probably due to the problems of recording. Both species are ‘Critically Endangered ’ under the I.U.C.N. criteria, but they are probably not at significant risk. Seed has been deposited in the Millennium Seed Bank and plants are being cultivated at the National Botani