Usnea flavocardia  

Thallus small, rarely exceeding 4 cm long, pale green to yellowish, becoming red-brown in the herbarium, paler towards the base. Branches rounded, rather stout, tapered and often ± constricted at the base, distinctly segmented by conspicuous annular cracks bordered by white rings of medullary tissue on the main branches, indicating conspicuous gaps between the segments at the point of attachment and on main stems. Papillae numerous, low, inconspicuous on main branches, fibrils sparse or absent. Pseudocyphellae numerous on ± eroded papillae, later becoming sorediate. Soralia numerous, especially towards the apical parts of the thallus, large (usually > half the branch width), tuberculate to slightly excavate, soredia rather coarse, isidiomorphs absent or only on young soralia. Medulla lax, outer part white, inner part pale lemon to primrose yellow adjoining axis, axis yellow-white to yellow.

Anamorph: not known.

Teleomorph: ascomata (apothecia) unknown.

Chemistry: Soralia C–, K+ brownish yellow, KC–, Pd+ yellow; medulla C+ yellow-orange, K+ yellow-orange, KC+ orange, Pd+ faint yellow (usnic, psoromic, ± 2-O-demethylpsoromic acids and ± 2 unidentified substances).