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8
HISTORY OF LICHENOLOGY
5. "Coriacei"; 6. "Scyphiferi"; 7. "Filamentosi." By this ordered sequence
Linnaeus showed his appreciation
of development, beginning, as he does,
with the leprose crustaceous thallus and continuing up to the most highly
organized filamentous forms. He and his followers still included the genus
Lichen among Algae.
A voluminous History of Plants had been published in 1751 by
Sir John
1
Hill , the first superintendent
to be appointed to the Royal
lichens are included under the Class
Gardens, Kew. In the History
"Mosses," and are divided into several vaguely limited ''genera" Usriea,
tree mosses, consisting of filaments only; Platysma,
flat branched tree
mosses, such as lungwort; Cladonia, the orchil and coralline mosses, such as
Cladoniafurcata ; Pyxidium, the cup-mosses; and Placodium, the crustaceous,
friable or gelatinous forms. A number of plants are somewhat obscurely
described under each genus. Not only were these new Lichen genera sug-
gested by him, but among his plants are such binomials as Usnea compressa,
other lichens
Platysmacorniculatum, Cladoniafurcata and Cladonia tophacea ;
are trinomial or are indicated, in the way then customary, by a whole sentence.
Hill's studies embraced a wide variety of subjects; he had flashes of
insight, but not enough concentration to make an effective application of
his ideas. In his Flora Britannica*, which was compiled after the publication
of Linnaeus's Species Plantarum, he abandoned his own arrangement in
favour of the one introduced by Linnaeus and accepted again the genus
single
Lichen.
Sir William Watson 3
, a London apothecary and physician of scientific
repute at this period, proposed a rearrangement and some alteration of
Linnaeus's sections. He had failed to grasp the principle of development,
but he gives a good general account of the various groups. Watson was the
progenitor of those who decry the makers and multipliers of species. So in
regard to Micheli, who had increased the number to "298," he writes: "it is to
be regretted, that so indefatigable an author, one whose genius particularly
led him to scrutinize the minuter subjects of the science, should have been
so solicitous to increase the number of species under all his genera: an error
this, which tends to great confusion and embarassment and must retard the
progress and real improvement of the botanic science." Linnaeus however
in redressing the balance earned his full approbation: "He has so far
retrenched the genus (Lichen} that in his general enumeration of plants he
recounts only 80 species belonging to it."
Linnaeus's binomial system was almost at once adopted by the whole
botanical world and the discovery and tabulation of lichens as well as of
other plants proceeded apace. Scopoli's 4 Flora Carniolica, for instance,
published in 1760, still adhered to the old descriptive method of nomen-
1 Hill i7 5 i. Hill'sgenus Collema is Nostoc, etc.
2 Hill 1760.
8 Watson 1759.
4 Scopoli 1760.