m [ 2064 ]
LICHEN pityreus.
Scurfy Imbricated Lichen.
CRYPTOGAMIA Algae.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Imbricated, flexible, glaucous-green;
hoary ashcoloured when d ry ; its segments dilated,
concave, rounded, crenate, very powdery at their
lateral margins ; pale and fibrous beneath. Shields
glaucous-black, with a broad, inflexed, very powdery
border.
Syn. Lichen pityreus. A ch. Prod. 124.
L. pulverulentus. Ehrh. Crypt. 285.
L . lanuginosus. Hojfm. Enum. 82. t. 10. f . 4.
1 ° Mr. W. Borrer and Mr. Turner belongs the honour of
first determining this as a species in England, though I gathered
it on a wall at Strumpshaw, along with L. ccesio-rufus,
t. 1040, in Ju ly l 783, but without shields, and was persuaded
to refer it to pulverulentus. Mr. Turner aptly named the plant
farreus, from its mealy aspect; but finding that Ehrhart has
published it by an appellation of similar meaning, we adopt
his name. It is strange that Acharius should have confounded
it, in his Prodromus and Methodus, with his own lanuginosus.
This latter is called memhranaceus by Dickson, an excellent
name for i t ; but still we cannot retain lanuginosus for the
plant before us, on account of its inaptitude, and the confusion
that would ensue.
L. pityreus is common in Norfolk and Suffolk on old
trees and brick walls, usually not very high above the ground,
running closely over tufts of moss and accumulated earth.
It always forms smaller patches than L . pulverulentus, t. 2063,
its lobes are more depressed and concave, its colour a paler
more .glaucous green when wet, and the lateral edges of its
segments are distinguished by thick whitish powdery tufts or
granulations, not found in the-former; neither are the fibres
of its under side so dense or near so black. The centre of the
frond becomes a mass of these powdery granulations, and the
thick incurved border of the shields, which are rare, small
and blackish, is covered with them. The Bev. G. R. Leathes
sent our specimens from Bury.