ASCOMYCOTA | LECANOROMYCETES > PERTUSARIALES > Pertusariaceae

Common name:            Bitter Wart Lichen

Synonym:                    Pertusaria amara var.amara

Habitat:                         Woodland, wayside trees

Substrata:                     Bark, but see text

Growth form:                Corticolous

Thallus:                  Crustose

Apothecia:                    Lecanorine, but very rare

BLS identity rating:        Graded 2/5 (visual identification possible, although spot-testing                       recommended to be sure)

Highly variable in terms of size and general appearance; thallus usually rather thick and well delimited; patches can be relatively small to wide spreading, sometimes as much as 20 x 50cm; whitish to pale grey, and typically visible from a distance; surface smooth to verrucose, more or less covered with globose soralia, 0.5-1.5mm dia., occasionally distributed in concentric lines, containing white, coarsely farinose soredia; apothecia very rare.

Apparently, this species is most easily confirmed by rubbing a moistened finger across the soralia and then tasting and, after a few seconds, noting the persistent bitterness.

Lepra amara is a common and widespread species on the bark of deciduous trees, both in woodlands or standing alone, seldom found on conifers, but sometimes occurring on the ground or on rocks overgrowing mosses.

Specimens growing on rocks are treated as a separate form by some authors, known as Lepra amara var.flotowiana. This variety typically has a less smooth, warty and cracked thallus with slightly larger soredia that have numerous tiny finger-like projections, giving it a much different overall appearance.