Classification of Plants.
For the groundwork of the system of classification which universally obtains at present, we are indebted to Linnæus, a Swede, born in 1707. In his classification of plants, Linnæus followed two different methods. In the one, he based his division of plants in classes and orders, upon certain peculiarities in the floral organs. This system, being thus founded on characters taken from certain parts of the plant only, without reference to others, and having something artificial in it, has for that reason been termed the artificial system, but it is now more generally known as the Linnæan system. In the other method, he arranged the plants according to certain general resemblances and affinities, in natural orders or families. This system, which is known as the natural system, has subsequently been much improved.
We use the term species, to designate a number of individual plants, which, in all essential and unvarying characters, resemble each other more closely than they do any other plant; the term genus or kind, to designate an assemblage of nearly allied species, agreeing with one another in general structure and appearance more closely than they do with any other species. Here, too, it must be obvious, that while all parts of the plant may furnish specific characters, the character of the genera are taken exclusively from the parts of fructification.
In the name of a plant both the genus and the species are given. The name designating the genus is called the generic name of the plant, the one designating the species, the specific or trivial name. Thus, for instance, we have the genus Viola, which includes the species Viola odorata, sweet violet; Viola canina, dog violet; Viola tricolor, heart’s-ease.
It is necessary to give the Latin names of plants, as the common name differs, not only in different countries, but even in different parts of the same country.
An assemblage or group of allied genera, agreeing in their general characters, though differing in their special conformation, is called an order or family of plants.
The sunflower, the daisy, the aster, and the dahlia, are, for example, plants of different genera, but which, all of them, belong to the same order or family.
All plants are divided into three primary classes—viz., Dicotyledons, Monocotyledons, and Acotyledons, as has been stated already.
A proper degree of familiarity with the systematic classification of plants is of the very highest importance to the student. A successful pursuit of this branch of the botanical science presupposes a thorough knowledge of the structure and physiology of plants, and requires, moreover, the aid of attentive observation, and also some diligence in collecting and arranging plants.