Collema nigrescens is a leafy (foliose) jelly lichen (Collema genus) found growing on the bark of trees such as bigleaf maples, in wetter coastal parts of California.

[1]: 34, 36  It is commonly called button jelly lichen or bat's wing lichen.

[1]: 34, 36  The photosynthetic partner is the Nostoc cyanobacterium that is spread throughout the thallus (main body part).

[1]: 34, 36  Although foliose in form, like all jelly lichens, the thallus is not differentiated, lacking layers or an upper or lower cortex (lichen) and the cyanobacteria is spread throughout the thallus.

[1]: 34, 36  It produces no reaction to lichen spot tests.