1 o S [ 156 i
L I C H E N tartareus.
‘Tartareous Lichen.
C R T P T O G A M I A Alga.
Gen. Char. Male, fcattered warts.
Female, fmooth fhields or tubercles, in which the
feeds are imbedded.
Spec. Char. Cruftaceous, whitilh. Shields yellow,
, with a white margin.
Sy n . Lichen tartareus. IJnn. Sp. PI. 16 08. HudJ. FI.
An. 529. With. Bot. Arr. V. 3 . 180.
Lichenoides cruftaceum et leprofum, acetabulis
majoribus luteis, limbis argenteis. Rail Syn. 7 1 .
DHL Muß. 1 3 2 . t. 1 8 . ƒ. 1 3 .
F r EQUEN T on rocks in Scotland and the north of England.
This is the largeft of our cruftaceous Lichens. The cruft has
a tuberculated furface, and is externally of a greyifh white,
though fnow-white within. In thicknefs it varies from an in-
feparable film running over moffes and turf, and affuming their
form, to a folid fubftance of full a quarter of an inch or more.
Its diameter is often 6, 8 or 10 inches. The fhields are from
a line to half an inch in breadth, flat, fmooth, not fhining, of a
yellowifh buff-colour, with a white elevated, often rugged,
margin. Thefe fhields prove occafionally proliferous, or aggre-
gate.
Lichen tartareus may be known, even without fructification,
by a peculiar pungent alkaline fmell when moiftened. It is
much ufed in dyeing. The gatherers carefully chctofe fuch fpe-
cimens as are of a firm denfe texture, and they never fcrape
the fame rock oftener than once in five years. It is prepared for
ufe with volatile alkali and alum, but the exa£tprocefs is kept a fe-
cret by the manufacturers at Glafgow. When fold to the Dyers,
it appears in the form of a purple powder, called Cudbear (a corruption
of Cuthbert, the name of its inventor). This powder
being boiled with woollen yarn, communicates its colour to it,
but not to vegetable fubftances. The Colour is far from permanent.
See Dr. Smith’s Tour on the Continent, vol. 1 . p. 198.