General Appearance:  Irregularly shaped, powdery patches, pale blue-green or blue-gray with white margins; the patches I - 3 cm (3/8 - 1 1/4 in) across. Thallus:  Thallus crustose, powdery, superficial, not embedded in the bark but so fragile and powdery that it cannot be peeled off; pale blue-green or blue-gray with a white margin. Apothecia:  Lacking. Soredia:  Lacking.

Comments: Lepraria mernbranacea is common on twigs but is often hidden by more conspicuous fruticose species.  A related species, Lepraria candelaris, is bright yellow, orange-yellow, or greenish-yellow.  It has a similar powdery, superficial thallus and lacks apothecia, soredia and isidia.  The only other common yellow lichen or fungus on twigs is Xanthoria polycarpa which has a foliose thallus and apothecia.