Usnea florida (All Fungi)
Thallus 2-5(-10) cm tall, ± erect, forming often dense, shrubby tufts, main branches to 1 mm diam., often curved, often with a few inconspicuous annulations. Branching irregular, thinner branches often contorted, surface grey-green, blackened at the base. Main stems covered with low, inconspicuous dense papillae and numerous fibrils to 10 mm long, mostly arising at right angles from the branches and becoming curved.
Anamorph: not known.
Teleomorph: ascomata apothecia, frequent, arising at apices of main and major lateral branches; disc 5-10 mm diam., at first ± concave, becoming flat, smooth or wrinkled, with abundant, often branched, marginal projections to 5 mm long. Ascospores 8.5-11 × 5.5-7 μm, ellipsoidal.
Chemistry: Medulla C–, K+ yellow, KC–, Pd+ orange (thamnolic and alectorialic acids, the latter especially in the apothecia).
Usnea florida is categorized as Near Threatened (Woods & Coppins 2012), It is a BAP Priority Species, and is cited in Sections 41 and 42 of the NERC Act 2006, and Section 2(4) of the Nature Conservation (Scotland) Act 2004. Considered as locally frequent but declining in SW England possibly due to rising levels of eutrophication (James et al. 2009). In Europe it is considered as restricted to old-growth and species-rich woodlands (Articus et al. 2002).
A distinctive and attractive species, typically richly fertile with abundant papillae and fibrils and always lacking isidia and soralia. U. florida appears to be a fertile counterpart of U. subfloridana; however, occasionally richly fertile specimens of the latter with only a few soralia occur, suggesting a continuum may exist between the two species. Juvenile forms of U. florida and U. subfloridana are often indistinguishable. The two taxa as understood here have different overall distribution patterns and tend to occur in differing habitats - particularly tree canopies for U. florida and a more diverse range of sites for U. subfloridana.
Initial molecular research suggests that Usnea florida should be amalgamated with U. subfloridana (Articus et al. 2002), and Saag et al. (2011) distinguished three cryptic taxa within the aggregate based on ITS sequences, all of which are known from the UK. Further study is needed, particularly in view of the conservation status of U. florida.
In GB&I, recorded from S & W British Isles and rarely in S and central Scotland (Dumfries, Lochwood, Loch Rannoch).
On twigs and branches in the canopy of broad-leaved trees, rarely on trunks, also on shrubs, palings and fence-posts, mostly in exposed, well-lit sites.