The genus
Ochrolechia comprises
crustose lichens that typically form uneven, often thick, crust-like growths. The
thallus, or body, of these lichens can vary in appearance from smooth and continuous to slightly cracked (). In some cases, the thallus may appear as scattered, convex warts or, more rarely, as minutely shrubby due to the presence of tiny or spine-like extensions. The colour of the thallus ranges from white or pale grey to dark grey, often with a greenish tint. A , which is a preliminary growth that may be visible around the edges of the thallus, is sometimes present and grey, though it may also be absent. The upper surface of the thallus generally lacks a distinct protective layer (), or may have a very thin cortex made up of thin-walled fungal filaments (
hyphae). The lichen's symbiotic partner, or , is a alga, which contributes to the lichen's overall colour and undertakes
photosynthesis. The reproductive structures of
Ochrolechia, the , are disc-like and typically expanded, though in rare cases, they may be pore-like (). The are usually yellowish or brownish-pink in colour, often covered with a fine white powdery coating known as pruina. The apothecia are surrounded by a well-developed , which is a rim of tissue derived from the thallus itself. In some species, a narrow , the tissue surrounding the
hymenium (spore-producing layer), is visible. The hymenium in
Ochrolechia apothecia is relatively tall, measuring between 150 and 200
μm. The , which supports the developing spores, consists of thin, densely branched, and interconnected filaments known as
paraphyses. The
asci, or spore-producing cells, contain between two and eight spores, and have thick,
amyloid walls, meaning they
stain blue with
iodine and are similar to those found in the genus
Pertusaria. The themselves are relatively large, lack internal divisions (), have relatively thin walls considering their size, and are smooth in texture.
Ochrolechia also reproduces
asexually through
pycnidia, which are flask-shaped structures embedded in the thallus. The
conidia (asexual spores) produced by the pycnidia are cylindrical to elongated and are straight rather than curved. Chemically,
Ochrolechia species are known to produce orcinol
depsides and
depsidones, particularly
gyrophoric and
lecanoric acids, as well as
xanthones and
fatty acids. These compounds contribute to the lichen's characteristics and can be used in chemical
spot tests to help identify the species. ==Species==