17
Isidiomorphs
of
Usnea
: similar to isidia, they develop in groups inside the soralia of some species of
Usnea
.
Soredia
: are tiny bundles of hyphae containing a few cells of the photobiont. They are much lighter
than isidia and originate from the medulla. They look like a fine powder. Important is the way in
which the soredia are located on the thallus (
soralia
). In the following we give some examples.
Diffuse soredia
: they are formed on the entire surface of the thallus, so that the whole upper surface
of the lichen looks powdery.
Maculiform soralia
: the soredia are formed in well-delimited parts of the thallus (soralia) and have a
circular shape.
Labriform soralia
: formed in well-delimited parts of the thallus, usually at the tip of lobes, lip-
shaped.
