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LICHEN Roccella.
D y e r s Lichen, or Orchall.
CRT PTO GAM IA Alga.
Gen. Char. Male, fcattered warts.
Female, fmooth ibields or tubercles, in which the
feeds are imbedded.
Spec. Char. Shrubby, folid, cylindrical, without
leaves, but little branched. Tubercles alternate,
powdery.
Syn. Lichen Roccella. Linn. Sp. PI. i6zz . Dickf.
Crypt, fa/c. 3 . 1 9 . Smith's'Tour, v. x. 1 9 8 .
Coralloides corniculatum fafciculare tinftorium, Fuci
teretis facie. D ill. Mufc. 1 2 0 . t. 17. / . 39.
I V I r . DICKSON has lately admitted this Lichen as a
Britilh native, on the authority of Mr. Goflelin, who found it
in Guernfey. Our fpecimen was gathered by Lord Vifcount
Lewilham on Portland Ifland. It grows on maritime rocks, very
common in the Mediterranean and the Levant. Linnaeus had
it too from China.
Its folid bafe is firmly fixed to the rocks, and produces a
thick tuft of worm-like items, round, acutely pointed, often
curved, more or lefs branched, fmooth, of a white, gray or
brownifh hue, and ftudded about their upper part with fcattered
tubercles, replete with white powder, which fome have
thought the feeds. Dillenius feems to think thefe tubercles
may be only the fpots where fcutellse have flood; in fact, the
fructification of this fpecies is not well known.
As an article of commerce it is of very great importance,
being extremely valuable for dyeing wool or filk any fhade of
purple or crimfon. For this purpofe it is fteeped in volatile
alkali, commonly diftilled from urine. Dillenius mentions 80I.
fterling per ton as a great price for Orchall, being almoft as
much again as it coll in the Archipelago, fo much better a
judge was he of Lichens than of the comfortable emoluments
of trade ! It has fince been fold at xoool. in times of fcarcity.