Lichen thallus (body) flattened (foliose), with relatively long, narrow lobes, somewhat overlapping. Color is dark brown to nearly black, but becoming much greener when wet. Underside densely covered with short root-like hairs (rhizines) which are black, mostly tipped with white. These rhizines stick out all around the edges of the thallus. The inside (medulla) is red orange, leading to both the common and scientific names (rubropulchra means "pretty red"). In the lower right picture you can also make out the thin green layer of algae, which provide the lichen with food, in between the dark gray upper cortex (skin) and the orange medulla. Sometimes produces powdery clumps along the edges; this powder, called soredia, is composed of both lichen and fungus and may blow or wash away and grow a new lichen. It also sometimes produces bowl-shaped fruiting bodies (apothecia) with dark brown insides, surrounded by white-tipped lashes.

Grows on wood or bark, especially in shady areas. Said to be the most common shadow lichen in the eastern U.S. In Wildwood it is very common on fence rails, and probably also on tree bark.

Shadow lichens share the characters of dark color, a thick layer of rhizines, and the tendency to turn green when wet. But, no other shadow lichen has orange inside. Thus, to be sure you have found the bloody shadow, look for areas that have been damaged (slugs are happy to do the dirty work by munching away) and show the orange underneath. If the lichen is completely intact, clip a very small piece off a lobe end with your fingernail and look for the color. Smooth shadow (P. ciliata) is very similar, but is much more likely to have bowl-shaped apothecia, never has soredia, and has a white medulla.

The "official" common name for this species is orange-cored shadow, but that name is boring, so I prefer bloody shadow.