The lichen forms olive-green, leaf-like growths up to 6 cm (2.4 in) across and is characterized by its sparse transparent surface hairs and disk-shaped fruiting bodies.

It is found primarily in southern California, where it grows mainly on oak trees in Mediterranean climate zones at elevations ranging from 640–1,700 m (2,100–5,580 ft), though it has also been reported from Oregon's Cascade–Siskiyou National Monument.

Analysis of nuclear ITS and mitochondrial SSU rDNA gene regions showed that the North American populations of what was thought to be M. glabra were genetically distinct from European and Turkish specimens, forming their own monophyletic clade.

The holotype specimen was collected from fallen branches of Quercus kelloggii in Palomar State Park, San Diego County, California at an elevation of 1,587 m (5,207 ft).

[4] Melanelixia californica is a foliose (leaf-like) lichen that grows in flat, overlapping layers adhering closely to its substrate.

It lacks several features common to other lichens, such as isidia (coral-like outgrowths), soredia (powdery reproductive structures), and pseudocyphellae (small pores).

The surface has a distinctive feature called a pored or fenestrated epicortex, meaning its outer layer contains microscopic holes.

Documented locations include:[3] Melanelixia californica represents a case of regional endemism, being part of the distinctive Mediterranean flora of California.