Powdery Sunburst Lichen

Description

Powdery Sunburst Lichen is a common and widespread lichen. It occurs in Europe, western Asia, and North America. It occurs throughout the United States, but it is mostly absent from the Great Plains and the Great Basin. It is very common in Minnesota.

Powdery Sunburst Lichen grows on bark and occasionally on rock and on concrete. It is commonly found on cemetery headstones.

The vegetative body (thallus) is leaf-like (foliose) and divided into small branches (lobes). It forms rosettes up to 1⅜″ (3.5 cm) wide, sometimes larger. The rosettes sometimes coalesce to cover much larger areas. It grows loosely attached to the substrate.

The lobes are flat to convex, flat (truncate) to round at the tip, up to 3 ⁄16″ (5 mm) long, sometimes longer, and 1 ⁄64″ to 1 ⁄16″ (0.3 to 1.5 mm) wide. They are semi-erect when fresh, becoming flattened with just the tips ascending in the older parts. The upper surface is smooth to shiny and deep orange when exposed to the sun, orange to yellowish orange in partially shaded areas, and pale yellow or greenish yellow in deep shade. There are tiny, globular chambers (pycnidia) embedded in the thallus with an opening through which fungal spores are released. The pycnidia are darker than the upper surface. The lower surface of the thallus is white and smooth to somewhat wrinkled. There are abundant, white to yellow, root-like structures (rhizines) attaching the lower surface to the substrate. The upper and lower surfaces of the lichen are formed of tightly packed, interwoven, fungal threads (hyphae) going in all directions (paraplectenchymatous).

Disk-like, spore-producing structures (apothecia) are rare, but when present they may be abundant. They are orange, stalked, up to ⅛″ (3 mm) in diameter, and shaped like a plate.

Similar Species

Ecology

Substrate

Bark, rock, cement

Growth Form

Foliose

Habitat

Hosts