Lichens are a unique and very interesting form of "plant" life, actually a combination of lichenizing fungi and an algal photobiont. Lichens come in three basic forms: crustose (like a crust), foliose (leaf-like), and fruticose (shrub-like, but in miniature).   Taxonomy of lichens is very interesting, based primarily on the types of chemical compounds form by the lichen, mostly acids.   Identification for many species requires chemical tests and examination of tiny spores, making field identification next to impossible for many species, particularly the crustose species.
Below are some information and photographs of various lichens, almost all unidentified at this point, that occur within Ventura County. They range in color wildly, and contribute to the biodiversity of Ventura County.   Eventually, I will have the names posted with each photograph.   Some photos will have more than one lichen species, so look carefully.
While the lichen flora of Ventura County has yet to be researched or written, based on currently available information, the following species of lichens are rare in Ventura County: Acarospora thelococcoides, Caloplaca chrysophthalma, Caloplaca epithallina, Caloplaca invadens, Caloplaca luteominia var. bolanderi, Caloplaca supyracella, Endocarpon subnitescens, Parmotrema austrosinense, Pertusaria flavicunda, Phaeophyscia kairamoi, Phaeophyscia sciastra, Protoparmelia badia, Punctelia punctilla, Ramalina fraxinea, Teloschistes flavicans, Teloschistes santi-jacobi, Vermilacinia [Niebla] ceruchoides, and Xanthoparmelia angustiphylla.
A list of lichens that have been collected from the Santa Monica Mountains, in Ventura and Los Angeles Counties, can be viewed here and is based on Kerry Knudsen's recent work. The Santa Monica Mountains, in both Ventura and Los Angeles Counties, occupies approximately 216,000 acres (57,450 hectares), and trends on an east-west axis. The Santa Monica Mountains is part of the Western Transverse Ranges ecological region.
I developed an annotated checklist of lichens of Ventura County.   See if you can add to this list.   I am sure there are many more species to be found and documented.
All photos copyrighted by David L. Magney 2003-2013