American Starburst Lichen

Description

American Starburst Lichen is found in the United States from Maine to Minnesota and south along the foothills of the Appalachian Mountains, in the northern Great Plains, the central and southern Rocky Mountains, and the southern Intermountain Region in the southwest. It grows on the bark of pine trees. It is almost restricted to pitch pine, jack pine, and Virginia pine in the east, and to ponderosa pine and Douglas fir in the west. It is rarely found on oak. In Minnesota it is found only on jack pine.

The vegetative body (thallus) is leaf-like (foliose) and divided into branches (lobes). It grows attached or loosely attached to the substrate (bark) by scattered, short, brown, anchoring structures (rhizines). The lobes are narrow, strap-shaped to rounded, and 1 ⁄64″ to 1 ⁄16″ (0.5 to 1.5 mm) in diameter. They are more or less randomly arranged and touch, crowd, or overlap adjacent lobes but are not fused to them. The margins are wavy or deeply pinnately cut, and the tips are often forked. The upper surface is grayish-green or ash-colored, smooth and somewhat shiny toward the edges, and wrinkled toward the center. There are usually tiny, globular chambers (pycnidia) embedded in the thallus with an opening through which fungal spores are released. The pycnidia look like black pinpricks in the tallus and are very conspicuous. They appear both on the margins and across the surface. The upper surface does not have powdery dull granules (soredia), shiny granules (isidia), or a chalky or “frosted” surface (pruina). The lower surface is whitish to pale brown, shiny, and somewhat wrinkled.

Disk-like, spore-producing structures (apothecia) are usually present, sometimes abundant enough to conceal the thallus. The disks are slightly raised, shaped like a plate, concave to flat or even convex, 1 ⁄16″ to ¼″ (2 to 7 mm) or more in diameter, pale brown or chestnut brown to dark grayish-brown. They may be flat or slightly raised, and stalkless or very short stalked. They appear near the margins on the upper surface.

Similar Species

Ecology

Substrate

Trees

Growth Form

Foliose

Habitat

Hosts

Jack pine