CRYPTOGAMIA Alga;.
G e n . Char. Male, scattered warts.
Female, smooth shields or tubercles, in which the
seeds are imbedded.
Spec. Char. Crust greyish-black, thin, circular,' with
a fine, radiating, compound, inky border. Shields
sessile, flatfish, coal-black* with a thick elevated
margin of their own substance and colour.
Syn. Lichen dendriticus. Ach. Prod. 77. Dicks. Crypt,
fasc. 4. 21.
Lecidea dendritica. Ach. Meth. 44.
Verrucaria dendritica. Hoffm. PL Lich. v. 1 . 90. t. 19.
ĥ 4-
N o t h in g can be more common than this Lichen on flint
or quartz.pebbles in exposed situations, as well on heaths in
Norfolk as on the mountains of Scotland ; yet it passed long
undetermined, and has been taken sometimes for the Linnseau
fusco-ater, sometimes for sanguinarius. The first British
botanist who paid any proper attention to it was the late Rev.
Dr. Walker of Edinburgh, who, when I showed him a specimen
from the Pentland hills in 1782, told me he had named
it quartxosus. Either this or our tuberculosus, t. 1 7 3 3 , (I speak
from memory,) is extremely fine on the large masses of white
quartz which crown the summit of Ben Lomond, and other
Highland mountains.
T h e specific name g iv en b y H o ffm an n and A c h a r iu s , being
e xtrem e ly ap t, in allu sion to the tre e -lik e appearance in M o ch o
s tones, w e adopt it , as v e ry desc riptive o f this species, the
m a rg in o f whose c rust is an elaborate compound b lu e ish -b lack
fr in g e o f the m o s t e xquisite ly fibrous structure. T h e rest o f the
c ru s t is g re y ish , in some degree tessellated, th in , bard and
sm o oth, o c c as ion ally alm ost w h ite . T h e shields are sessile, o f the
darkest possible b la ck both in their disk and border, y e t somew
h a t s h in in g ; flat w h en yo u n g , rather con v e x w h en o ld :
som etimes, th ou gh ra re ly , th e y are ranged in a concentric
manner lik e those o f L . conccntricus, t. 246»
fiiblùrh'ds Tiy J it f Seira-T/)’ZoriHon-.