Jè& [ 2547 ]
LICHEN dubius.
Doubtful Board Lichen.
CRYPTOGAMS Algos.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust leprous, pale brownish grey, indeterminate.
Tubercles black, convex, slightly
immersed in the crust; bordered when young.
Syn. Lecidea dubia. Turn. andBorr. Lich. Brit. Mss.
C om m o n on boarded buildings, though hitherto overlooked
and undescribed, unless it may be the Lecidea aitema of Acha-
rius’s Lich. Universalis, of which Mr. Borrer, to whom we are
obliged for calling our attention to the plant, has some suspicion.
We confess that we have often passed over this minute production,
chiefly upon pales or boards of deal, in exposed situations
in Norfolk, as well as around London.
The crust consists of minute, but elevated and compound,
granulations, forming indeterminate confluent patches, paler
and more grey than those of L. querneus, t. 485, which this
species otherwise most resembles. The minute clustered tubercles
however are quite black externally, though brown when
scraped or cut, and have when young a very evident raised
black border.