Prim. Fl. Holsat. (Kiliae) 2: 7 (1780).
Basionym: Lichen floridus L., Sp. Pl. 2: 1156 (1753).
TYPE: Sweden? (LINN 1273.300 lectotype, Howe, Bull. Torrey Bot. Club 39: 201, 1912; restricted to lower specimen by Clerc, Cryptog., Bryol. Lichenol. 5: 341,1984).
Thallus: fruticose, erect, to 10 cm long, stiff; ramifications usually isotomic-dichotomic with divergent branches. Base black, often with distinct annulations. Main branches tapering; secondary branches not narrowed at their point of attachment to the main stems. Segments ? distinct, cylindrical and terete. Papillae verrucose sparse to numerous; tuberucles and ?bercules absent; ?brils 2- 4 mm long, slender. Soralia absent. Cortex thick (913%), mat in longitudinal section; medulla thin (1120%), dense to compact; axis moderately thick (3854%); A/M = 0.8- 6. Apothecia usually numerous, terminal on main branches; disc to 2 cm across. Spores 8.5- 11 x 5.5- 7 μm. Pycnidia not observed.
Photobiont: Data lacking.
Chemistry: Medulla C, K+ bright yellow, KC or KC+ rose; PD+ yellow-orange (thamnolic, ? alectorialic, ? bourgeanic acids) or C, K, KC or KC+ rose, PD (squamatic acid, ? alectorialic acid, ? bourgeanic acid).
Ecology: On deciduous trees in open situations, often on the trunks and twigs of Acer, Fagus, Fraxinus and Quercus.
Molecular data: Genbank
Distribution: Scattered occurrences inland in southern Sweden, in Norway close to the coast from Akershus to Nordland. Probably extinct in Denmark. A temperate and hemiboreal distribution; locally common on the European continent and in the British Isles.