Allocetraria oakesiana (aka Cetraria oakesiana & “Yellow Ribbon Lichen”)
Substrate: On bark & wood, usually of conifers or birch; sometimes on rock; typically in shaded forests.
Range: All throughout North America, except Nevada, northwest Alaska, & northeast Canada.
Description: mostly appressed; lobes strap-shaped, crisped at the edges, branched, 1 – 4 mm wide. Lower surface pale brown to almost white, somewhat wrinkled, shiny, with sparse rhizines.
Color: Yellowish green, uniform.
Sorelia: Yellowish, almost entirely marginal, granular, sometimes developing from coarse pustules
Lobules: Rarely with tiny, almost granular lobules.
Medulla: White to pale orange.
Photobiont: Green (Trebouxia).
Apothecia: Rare, marginal or laminal, with pale brown disks.
Spores: Spherical, ca. 5 um in diameter
Conidia: Usually thread-shaped, 8 – 10 um long, but rather variable in shape & size.
Chemistry: Medulla PD-, K+ yellow, KC+ orange to red-orange, C- (caperatic, protolichesterinic, lichesterinic, & secalonic acids).
Lookalikes: Except for the color, this species is similar to Tuckermannopsis chlorophylla. It is also very close to species of Ahtiana but has different conidia.
Bibliography: Lichens of North America, by Brodo, Sharnoff, & Sharnoff
Database Entry: Distance Everheart 12-26-13