About Pentanema salicinum (L.) D.Gut.Larr., Santos-Vicente, Anderb., E.Rico & M.M.Mart.Ort.
Pentanema salicinum is an upright herb that grows 20–80 centimetres (7.9–31.5 in) tall. It has a thin stem and narrow, elongate, alternate, stemless leaves; both the stem and leaves are covered in coarse hairs. Its flower heads grow singly at the top of the stem, and measure 2.5–4 centimetres (0.98–1.57 in) in diameter. Each flower head holds 35–70 yellow ray florets and 100–250 yellow disc florets.
Pentanema salicinum is widespread across mainland western Europe, ranging from Spain through France, the Benelux countries, Germany, Poland, Denmark, and southern Scandinavia. It has a very restricted distribution in the British Isles, where it is only found in a small area of south-central Ireland, around Lough Derg in north County Tipperary and south-east County Galway. Currently, the species is only confirmed to occur at a single locality, as it has been extirpated from its former sites by human activity. It has become a flagship species for conservation, and a coordinated reintroduction program is already well underway.
Pentanema salicinum is classified as a member of the Lusitanian flora, meaning it belongs to a group of plant species that are restricted to south-west Ireland, absent from the rest of the British Isles, and more typically found in the Mediterranean. It is unknown how this group of plants became established in Ireland, but it most likely occurred within the last 10,000 years, after the end of the last ice age.
