E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Common Name: The Starburst Lichens. Describes the centrifugal growth pattern characteristic of the species.
Small stratified foliose lichens, corticate above and below, sorediate, lobes closely appressed, elongatelinear to elongate, averaging to 1–2 mm wide, thin. Upper surface whitish grey or pale yellowish green, more or less shiny, especially at lobe tips. Lower surface pale brown to blackening, bearing short, simple rhizines. Medulla white. Photobiont green.
Apothecia located over upper surface, disc brown; spores simple, sausage-shaped, colourless, 8 per ascus.
Notes: Parmeliopsis is a boreal–temperate genus consisting of three species worldwide. All of these occur in North America, though only two are present in B.C.

Species description:
Upper surface yellowish or yellowish green; soredia present AND
Over bark (very rare over rock); upper surface generally dull toward thallus centre when mature; widespread; medulla K-, PD-

Reactions:
Cortex KC+ yellow.

Contents:
Divaricatic and usnic acids.