A global community of nature enthusiasts
photographing and learning about wildlife
White in color, as if covered with snow. As a fruticose lichen, Usnea appears as a shrub-like growth on host trees. It reproduces via vegetative means through fragmentation, asexual means through soredia, or sexual means through ascogonium and spermatogonium. The growth rate of lichens in nature is slow, but the growth rate has been sped up in laboratory conditions where Usnea is being cultured.
Usnea often grows on sick or dying trees due to the pre-existing loss of canopy leaves, allowing for greater photosynthesis by the lichen's algae; this leads some gardeners to mistakenly blame the lichen for the tree's leaf loss and illness. Usnea is very sensitive to air pollution, especially sulfur dioxide. Under bad conditions they may grow no larger than a few millimetres, if they survive at all. Where the air is unpolluted, they can grow to 10–20 cm long.