Silversword plant. The elongated leaves of the silversword plant (Argyroxiphium sp.) are covered in fine grey hairs, which give the plant its silver appearance. This plant is native to the Hawaiian islands and is threatened by the arrival of alien plants and animals. Its numbers have been decimated by the arrival of herbivores such as sheep and goats, and it now only remains in inaccessible rocky areas. As well as this, the insects which pollinate its flowers are having to compete with several species of insect invaders, which also contributes to the risk of extinction. Photographed in Hawaii, USA.