CHARACTERS, in botany, the descrip tion of the genera of plants, so termed by Linnzeus ; hence the generic character of any plant, and the definition of the ge nus, are synonymous terms. The term character is not extended by that author to the species of plants, because he never gives the complete description of any species ; but only enumerates those cha racters or circumstances in which it dif fers from all the other species of the same genus. This observation sufficient ly illustrates the different methods which are observed in the Genera and Species Plantarum. In the former work, all the parts of the flower and fruit from which the characters of the genera are derived are accurately and completely described; in the latter, such striking circumstances only of the stem, leaves, buds, roots, &c. are mentioned, as sufficiently distinguish the species in question from every other of that genus to which it belongs.
In general, characters, or characteris tical marks, according to the idea of systematic writers, are certain external signs, obvious in the appearance of na tural bodies, by means of which they are distinguished from one another. These signs being collected,and express. ed by proper words, lay the foundation at once for definition,distribution, and de nomination, the three grand parts ofprac tical botany. The characteristic mark of each genus is to be fixed from the fi gure, situation, connection, number, and proportion of all the parts. Any part of a body, considered either in itself or with relation to others, is found to pos sess all the properties just enumerated. Characters, therefore, may be drawn from all the parts, to define the difference of bodies ; thus the leaf, stem, flower, and its parts, in plants; the foot, wing, fin, in animals ; all differ in their figure, situation, number, and proportion, and exhibit Characters proper for distinction. Experience shows that one part, or pro perty of a part, varieemom than another; in constituting a method, therefore,those parts and properties are to be selected which vary least. Thus the parts of flowers in vegetables, the feet,fins, beaks, in animals, are more fixed, with respect to the above mentioned properties. Again, the figure and number of these parts are more apt to vary than their;situatiori, con nection, and proportion ; the characters, therefore, are, if possible, to be taken from these last.
Arttjlcial artificial cha racter, otherwise called accidental, and, by Linnaeus, factitious, is drawn indiscri minately from different parts of the plant, and admits of fewer or more characteris tical marks than are absolutely necessary for distinguishing the classes, genera, and species. Linnzus, who particularly applies all the characters just enumerated to the distribution of the genera, estab lishes for a criterion of the artificial cha racter, that it can never distinguish the genera in a natural order ; being calcu lated merely for discriminating such as arrange themselves under the same arti ficial order. To the head of artificial characters is referred, by Linnaeus, the description of the genera, in the methods of Tournefort, Ray, Rivinus, Boerhaave, and most of the other systematic bo tanists. The classical characters only, in the sexual method, are deemed ar tificial : the generical, as exhausting the description of the parts of fructification, its author considers as true natural cha racters.
Linnzus's , idea of an artificial charac ter is well expressed by Ray, when he says, that no more characteristical marks of the genera are to be collected, than are found absolutely necessary for deter mining the genus with certainty and pre cision.
Essential essential character discriminates one plant from another by means of a single mark, so striking and particular, as to distin guish the plant in which it is found from every other at first sight. It serves, says Linnxus, to distinguish such genera as arrange themselves under the same na tural order. The essential character of the classes and genera, by the consent of all the modern systematic botanists, ought to be drawn from one of the seven parts of fructification ; that of the species from any of the other parts, as the stem, leaf, root, buds, he.
Natural character in cludes the two former, and collects all the possible marks of plants. It is useful, says Linnzus, in every'method lays the foundation of the systems ; remains un changed, although new genera be daily discovered ; and is capable of emendation by the detection of new species alone, which afford an opportunity of Excluding such characteristical marks as are totally superfluous. Ile adds, that the Genera Plantarum first introduced these charac ters into the science.