up in situations
that are apparently the most unfavourable to the sustenance of
vegetable life. When gathered it has a soft delicious odour, which it
retains for a great length of time. Mr. Glas, in his history of the
Canary Islands, gives so clear and accurate an account of its growth,
that I will avail myself of his description, as being not only the best
I have met with, but as containing all the necessary particulars. "The
orchilla weed," he observes, "grows out of the pores of the stones or
rocks, to about the length of three inches: I have seen some eight or
ten inches, but that is not common. It is of a round form and of the
thickness of common sewing twine. Its colour is grey, inclining to
white: here and there on the stalk we find white spots or scabs. Many
stalks proceed from one root, at some distance from which they divide
into branches. There is no earth or mould to be perceived on the rock
or stone where it grows. Those who do not know this weed, or are not
accustomed to gather it, would hardly be able to find it, for it is of
such a colour, and grows in such a direction, that it appears at first
sight to be the shade of the rock on which it grows."

Mr. Glas adds, that the best sort is of the darkest colour, and nearly
round; and that the more white spots or scabs it exhibits the better.
It is found in considerable quantities in the Canary Islands, the Cape
de Verds, the Azores, and the Madeiras, and such are the nice varieties
and properties incidental to the different soils, (if they may be so
called,) or climates, that although the above clusters of islands are
at no great distance from each other, the difference in the produce
makes a very considerable difference in the value of the article. It is
also found on the coast of Barbary, and the Levant, and on that part of
the coast of Africa, which lies adjacent to the Canary-Islands; but,
owing to the want of seasonable rains, the produce of the latter is not
rapid or abundant, although the quality is excellent. It has been
suggested, that the orchilla was probably the Gertulian purple of the
ancients; a conjecture which is strengthened by the fact, that the
coast of Africa, where the orchilla abounds, was formerly called
Gertulia. That the vivid dye which resides in this weed was known to
the ancients, does not admit of any doubt.

The plant belongs to the class Cryptogamia, and order Algae, of the
Linnean system, and to the class Algae, and order Lich