Usnochroma

Usnochroma has a crust-like thallus that is pale yellow in colour. It does not contain anthraquinones, compounds often responsible for the yellow and orange colours in many lichens of the Teloschistaceae. The outer layer, or cortex, occurs in one of two tissue structures: or . The reproductive structures, known as apothecia, are in form, characterized by a very thin outer edge and a rusty orange-coloured central . The spores of this genus are distinctive, being with an elongated partition, or septum. There is no observed presence of pycnidia, another type of reproductive structure. The thallus contains usnic acid and gyrophoric acid. In addition to these, the apothecia contain parietin. Buellia badia and Tremella caloplacae are lichenicolous fungi that have been recorded parasitising Usnochroma carphinea. ==Species==