The lichen flora of two sites in the Mojave Desert, California, USA

Forty lichen species in 24 genera were identified from selected sites in the Mojave National Preserve, California. Collections were made from north-facing basalt flows, on rock, soil, and dead wood. Environmental conditions in the Mojave Desert (extreme heat and drought) generally restrict development of lichen communities except in protected locations. Saxicolous lichen communities were best developed along north-facing aspects of extensive basalt flows. South-facing exposures were completely devoid of lichens. Common saxicolous lichens, included Dermatocarpon miniatum, Lecanora garovaghi, Lobothallia praeradiosa, Pleopsidium flavum, Rhizoplaca melanophthalma, and Thyrea confusa. Terricolous lichen communities were generally patchy and poorly developed but showed best development along the edges of ephemeral watercourses. Terricolous lichens included Collema tenax, Peltula obscurans var. hassei, and Placidium squamulosum. Xanthoria fallax was locally common on decorticated branches of Blackbrush (Coleogyne ramosissima) and occasionally on Creosote bush (Larrea tridentata).