Usnea mutabilis is a grayish-yellowish pale green, unequally branching, shrubby (fruticose) 3–7 cm long lichen commonly anchored on holdfasts on trees, mostly in eastern North America, sometimes in chaparral shrubs or pines in California.[1] It is darker green than other members of the genus Usnea.[1] The surface is covered with isolated, or clusters of, isidia.[1] It lacks apothecia.[1]
The common name is bloody beard lichen.[1] The thick axis and medulla are dull red.[1]