Jan. 1905] 
Elementary Mycology 
37 
the genus of Mints {Mentha), and the genus Agaricus. A genus 
then is a group of species that strongly resemble each other. 
There are always a few, a greater or lesser number of important 
or essential characters that are common to all the species of the 
genus; some one if not several or all of these distinctive points 
would be absent from every other genus of plants. Proceeding in 
the same manner with genera — that is, grouping those together 
which have some evident and important resemblance — we get 
Families; these consist of related genera. Again, Families of 
plants having evident relationship constitute Orders. These may 
be grouped in larger associations that can be denominated 
Classes, and thus the entire Vegetable Kingdom may be synoptic- 
ally arranged. 
Nomenclature.— It has been found convenient and suffici¬ 
ently definite for ordinary purposes to apply a scientific name to 
the numerous easily recognized kinds of plants and this consists 
simply of the genus and the species; thus the White Oak is called 
Quer'-cus al'ba, the Artichoke He-li-an -thus tu-ber-o'-sus, the 
Common Mushroom A-gar'-i-cus cam-pes'-tris, the Morel Mor- 
chel'-la cs-cu-len -ta, the Sunflower Rust Puc-cin -i-a he-li-an -thi 
etc. The botanical name is therefore binomial, consisting of a 
generic and a specific name — the genus placed first, followed by 
the species. In case a sub-species is to be designated a trinomial 
wpuld be used, as He-li-an -thus tu-ber-o -sus sub-ca-nes cens, 
etc. Authors occasionally indicate a “form,” where in their opin¬ 
ion the designation of sub-species would scarcely or not at all be 
warranted, and in such case the scientific name might be a quadri- 
nomial, or if a trinomial the name following the species would be 
used for a “form” (latinized to “forma,” or abridged to “for.” 
or It will be found in Manuals, Monographs, Printed 
Lists, etc., that the author of the species-name is always indicated; 
thus Quercus alba L., and Morchella esculenta Pers., indicate that 
Linnaeus named the White Oak and that Persoon is the author 
of the botanical name of the Morelle. It sometimes happens that 
two different names have been applied to a species. In such case 
the one first given stands and all later names that may have been 
applied to that species are synonyms and to be discarded. In 
many cases it has happened that the true relationship of the plants 
was not correctly apprehended and therefore placed in a wrong 
genus; or it may be that subsequently a valid genus has been pro¬ 
posed by some botanist to receive a certain species or two or three 
species of one of the existing genera. In such case the name — 
for example, of the Kentucky Coffee tree—is written thus: Gym- 
noc'-la-dus di-oi'-ca (L.) Koch, and the explanation is this: 
Linnaeus took this plant to be a member of the genus Gui-lan- 
di'-na, and hence the name in early botanical literature was Gui- 
lan-di'-na di-oi'-ca L. (1753). Later another genus was pro¬ 
posed, Gym-noc -la-dus; and it must be explained that a new spe- 
