among botanists, is synonymous with the definition of the genera of plants.—The term character is not extended by Linnaeus to the species of plants, because he never gives the complete description of any species; but only enumerates those characters or circumstances in which it differs from all the other species of the same genus. The characters which are known by the sense of sight, are only to be depended on in distinguishing bodies; those which are acquired by the other senses, as the taste and smell, being rarely or never to be admitted as marks of distinction. The characteristic mark of each genus is to be fixed from the figure, situation, connection, number, and proportion, of all the parts*. Linnaeus has suggested four different characters; the artificial, the natural, and the habitual; which are all equally applicable to the higher and lower divisions. The first is drawn indiscriminately from different parts of the plant, and admits of more or fewer characteristic marks than are absolutely necessary for distinguishing the classes, genera, and species. Linnaeus establishes for a criterion of the artificial character, that it can never distinguish the genera in a natural order; being calculated merely for discriminating such as arrange themselves under the same artificial order. In the lexical system, the classical characters are only considered as artificial. The essential character distinguishes one plant from another by means of a single mark so striking and particular as to distinguish the plant in which it is found, from every other, at first sight. It serves to distinguish such genera as arrange themselves under the same natural order. The essential character of the classes and genera ought to be taken from one of the seven parts of fructification; that of the species from any of the other parts; as the stem, leaf, root, buds, &c. The natural character includes the two former, and collects all the possible marks of plants. It is useful, says Linnaeus, in every method; lays the foundation of the systems; remains unchanged though new genera are daily discovered; and is capable of emendation by the detection of new species alone which afford an opportunity of excluding such characteristic marks as are totally superfluous. The habitual character drawn from the habit or port of plants, was the invention of the earlier botanists who knew no better rule for the distribution of vegetables. This character has never been employed but in distinguishing the species; though Linnaeus seems to think that it may be used with caution, and in default of other characters, for ascertaining the genera.

See Botany.

Characteristic, in the general, is that which characterizes a thing, or person, i.e., constitutes its character, whereby it is distinguished. See Character.

Characteristic, is peculiarly used in grammar, for the principal letter of a word; which is preserved in most of its tenses and moods, its derivatives and compounds.

Characteristic of a Logarithm, is its index or exponent. See Logarithm.

Characteristic Triangle of a Curve, in the higher geometry, is a rectilinear right-angled triangle, whose hypotenuse makes a part of the curve, not sensibly different from a right line. It is so called, because curve lines are used to be distinguished hereby. See Curve.