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LICHEN umbrinus.
Dark-stained Wart Lichen.
CRYPTOGAMIA Algae.
Gen. Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
. Spec. Char. Crust of a deep olive black, solid, most
minutely cracked. Tubercles of the same colour,
half immersed, slightly convex, with a central pore.
Syn. Lichen umbrinus. Ach. Prod. 14.
Verrucaria umbrina. Ach. Meth. 122.
ALTHOUGH common every where on shady rocks and
stone walls, even about houses, this minute Lichen has not
yet found a place in any work on British plants, except it
may have been taken by some botanists, as the ingenious
Acharius suspects, for L. antiquitatis, or L. fusco-ater. We
confess, though we never took it for either of those, we
never understood its real structure, till the descriptions of this
writer, illustrated by specimens from himself, explained it to
us. The specimen in our plate, more perfect than usual, as
having the central pore visible on the tubercles, was sent by
Mr. James Turner from Gorlestone church, Suffolk.
The crust forms a permanent spot, an inch or two wide,
of a very dark olive black when wet, in which state it is in
some degree soft and friable, its surface rather uneven, and
very minutely cracked. When dry it grows blacker and harder.
The tubercles are partly immersed, their surface a little convex,
their colour rather paler or greener when wet, and they have,
when perfect, a central black pore, which marks Dr. Acha-
rius’s genus of Verrucaria. They are always distinguishable
from the crust by being round and without cracks. Careless
observers might take this for L. niger, t. 1161, from which
it is totally distinct in nature.