Nephroma laevigatum Ach.
Mustard paw

Introduction to the Lichens


© Jim Riley     (Photo ID #12354)


E-Flora BC Static Map

Distribution of Nephroma laevigatum unavailable

Species Information

Common Name: The Paw Lichens. Alludes to the presence of brown, paw-like apothecia on the lower surface; in all other genera the apothecia are located over the upper surface or along the lobe margins.
Small to medium or large stratified foliose lichens, corticate above and below, sorediate or isidiate or not, lobes loosely appressed to loosely attached, short to elongate, averaging to 0.5–2 (–3) cm wide, thin. Upper surface greenish, greyish or brownish, dull or shiny. Lower surface pale to dark, naked or more or less covered in dense woolly tomentum, occasionally also tuberculate, lacking rhizines. Medulla white (yellow to orange). Photobiont green and/or blue-green.
Apothecia appressed over lower surface near lobe tips, disc brown; spores 4-celled, spindle-shaped, pale brown, 8 per ascus.
Over trees, logs, mossy rocks.
Notes: Nephroma is a cosmopolitan genus of about 40 species worldwide. Nine are known from North America and all occur in B.C. Although thin-layer chromatography has been used successfully in the elucidation of some Nephroma species (see for example James and White 1987), spot tests are of little taxonomic value in this genus.
Species description:
Photobiont a dark blue-green cyanobacterium; upper surface brownish, greyish, or if greenish, then also sorediate or isidiate; ecology and distribution various AND
Lower surface naked or minutely woolly, “woolliness” not obscuring fine details of surface wrinkles; soredia present or absent AND
Thallus lobulate, but lacking soredia or isidia (Note: lobules may, however, occasionally appear isidia-like; in this case “isidia” are usually borne singly) AND
Lobe margins and/or upper surface usually lobulate; upper surface naked or minutely woolly; medulla white or orange, K- or K+ reddish; apothecia present or absent; generally over rock AND
Medulla at least in part orange, K+ reddish; coastal
Medulla K+ reddish.
Various triterpenoids, an orange anthraquinone and various other substances.

SourceLichens of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration ByTrevor Goward

Habitat and Range

Habitat: Frequent over rock and occasionally deciduous trees and shrubs in open coastal localities

World Distribution: incompletely circumpolar, S to CA.

SourceLichens of British Columbia


Synonyms and Alternate Names:
Nephroma laevigatum auct.
Nephroma lusitanicum Schaerer