_Such as consist of a dry and friable matter, more or less thick,
formed into flat crusts, very closely adhering to whatever they grow
upon._
Some of the species of this division consist of an exceeding fine thin
crustaceous, or rather, as Micheli calls it, farinaceous matter, the
fructifications appearing in the form of tubercles. Others consist of
a thicker scabrous crust, having the fructifications in the form of
little cups, called _scutellæ_.
This division contains the first order of the _lichenoides_ of
Dillenius; the 5th, 6th, and 7th orders of Haller’s lichens; the
_lichenes leprosi_ and _crustacei_ of Linnæus; and several of the
_placodium_ of Hill.
The species are numerous, and most of them very common on rocks,
stones, old walls, the bark of trees, old pales, _&c._ which are
commonly covered over with them, in undisturbed places. They form a
very agreeable variety, and some of them have a very elegant appearance.
Dr. Dillenius describes a species of this order, which he found upon
the tops of the mountains in Caernarvonshire in Wales; and which the
inhabitants told him they used as a red dye, and found it preferable
to the cork, or arcel, which they call _kenkerig_. He has intitled it,
in English, _The white tartareous scarlet-dying lichenoides_[98]. He
is of opinion, that this is the moss which Martin mentions, in his
account of the Western Islands of Scotland, under the name of _corkir_;
with which the inhabitants of the island of Sky dye a scarlet colour.
They prepare it by drying, powdering it, and then steeping it for three
weeks in urine. Linnæus queries whether this moss be not the same as
his _lichen calcareus_[99]; a species so peculiar to limestone rocks,
that where-ever that stone occurs among others, it may be distinguished
at the first view by this moss growing upon it. This is a singularity
which Dr. Dillenius has not mentioned in his moss: on the other hand,
Linnæus does not mention any tinging property in his.
The _pérèlle d’Auvergne_, or _orseille de terre_, of the French,
belongs to this order of lichens, and is called by Dillenius[100] _The
crayfish-eye-like lichenoides_. It is gathered in large quantities in
the province of Auvergne, and is used as _orchel_; to which however
it is greatly inferior. They prepare it with lime and urine; and were
acquainted with its use as a dye long before the Canary weed was
known[101] to them; and it is at this day in more common use than
the _orchel_. We have it frequent with us upon old walls, rocks, and
stones; but it is to be had in larger quantities in several other parts
of Europe.
The mealy tartareous _lichenoides_[102] with brown dishes, forms an
article of trade with the people of West Gothland. They manufacture
a beautiful red dye from it, which they sell under the name of
_byttelet_[103]. Dr. Hill says we have this moss abundantly in
Leicestershire and Warwickshire.
The Welch make a red dye, with urine, from another moss of this order,
which Dillenius describes[104] by the name of _The large leprous
lichenoides with yellow plates_. These are not the only species, which
are endowed with a tinging quality: other kinds have been observed to
give a red or purple colour to paper in which they have occasionally
been inclosed. Doubtless several would, upon sufficient trials, be
found to answer equally well with the _orchel_.
With regard to these crustaceous mosses in general, it is highly
worthy our regard, that in the œconomy of nature they answer singular
and important uses. To an unobserving eye, no class of vegetables may
appear more insignificant, or less adapted to advantageous purposes
in the creation, than these. This vulgar estimation of things is
frequently erroneous; and it is certainly so in the instance before
us. These minute and seemingly insignificant mosses serve, under some
circumstances, to valuable purposes. No sooner is a rock left bare by
the sea, but these lichens lay the foundation for its future fertility.
Their seeds, which are presently brought thither by the winds, soon
cover it all over. These corrupting, presently afford a soil sufficient
to nourish other smaller mosses; which, in their turn, form one deep
enough for larger plants and trees; and thus the rock becomes a fertile
island[105].