Various examples of lichens in Arkansas and Oklahoma. A. Lichens growing on oak (Quercus) tree near Big Fork, Polk County, Arkansas. B. Crustose lichens covering rocks on escarpment at Blue Haze Vista, Polk County, Arkansas. C. Foliose lichen on Quercus limb, McCurtain County, Oklahoma. D. Lichen on pine (Pinus) cone, McCurtain County, Oklahoma.