His diagnosis of the species was as follows: "Cetraria oakesiana is characterized by a somewhat leathery, expanded thallus that is smooth and greenish-yellow on the upper surface, and pale chestnut-brown underneath.

Tuckerman dedicated species epithet to his friend, the American botanist William Oakes of Ipswich, Massachusetts.

[7] Usnocetraria oakesiana is a foliose lichen, meaning it has a leafy appearance with a structure that is dorsiventral, indicating that the upper and lower surfaces are distinctly different.

The lower surface also features scattered rhizines, which are root-like structures that help anchor the lichen to its substrate.

When present, they are zeorine (a type of apothecium with both thalline and proper margins), usually located near the edges of the lobes, and can be up to 7 mm across with a pale brown disc.

[8] Usnocetraria oakesiana has a chlorococcoid photobiont, meaning that its symbiotic algal partner belongs to a group of green algae with small, round cells.