ASCOMYCOTA | LICHINOMYCETES > CANDELARIALES > Candelariaceae

Genus Candelaria, meaning 'candle' - from the candle-light colour of the thallus

Common name:            Lemon Lichen

Synonyms:                    -

Habitat:                         Heathland (this entry), wayside trees, fences

Substrata:                     Bark, worked timber, occasionally rocks and walls

Growth form:                Corticolous, lignicolous (saxicolous)

Thallus:                  Foliose

Apothecia:                    Lecanorine, but rare

BLS identity rating:        Graded 1/5 (identification should be straightforward)

Thallus typically forming small, often discrete, neat cushions, rarely much than 2cm across, or irregular patches, sometimes coalescing, but often in scattered fragments; more or less appressed to the substratum; tiny flattened or very slightly wavy lobules, divided into small straps, no more than 0.5mm wide by 1.5mm long, usually overlapping, somewhat raised and fan- like, tips finely incised delimiting a sorediate margin; upper surface yellowish-green or a yellow-mustard colour in shade, brighter, lemon or chrome-yellow in sun; underside matt, corticate, almost white.

Apothecia are rare but, were present, 0.4-1mm dia., disc pale brownish-yellow or dark greenish-orange, with a smooth thalline margin.

Candelaria concolor is a relatively common and widespread lichen in the south, but with more scattered distribution further north, albeit increasing in many areas due to its tolerance for nitrogen; it's very much a species of warm, well-lit, locations, occurring primarily on the nutrient-rich wayside broadleaved trees, especially Ash (Fraxinus), Elm (Ulmus), Maple (Acer) and Willow (Salix), but also on other trees and shrubs, most often found in branch axils and along bark crevices; also occurring on fences and other wooded structures, and more rarely on nutrient-enriched rocks and walls.

Not to be confused with Xanthoria ulophyllodes, which is less delicate in appearance and generally has a deeper orange coloured thallus, or Xanthoria ucrainica, which can look very similar although has more erect and less lace-like lobes. They are members of the Xanthoria candelaria group of species, all of which test K+ crimson, whereas Candelaria concolor tests negative. It's an easy and reliable way of separating the species.

The examples featured below that were photographed at Holt Heath were on an old, rather dead-looking gorse; the other two were found on small branches of a Rowan tree that had to be cut down, All were tested K- to rule out any chance of Xanthoria.