The nomenclature of Botany as rescued from confusion by Linnæus, has in modern times been in some danger of relapsing into disorder or becoming intolerably extensive, in consequence of the multiplication of genera by the separation of one old genus into several new ones, and the like subdivisions of the higher groups, as subclasses and classes. This inconvenience, and the origin of it, have been so well pointed out by Mr. G. Bentham[65], that I shall venture to adopt his judgment as an Aphorism, and give his reasons for it.
[65] Linnæan Society’s Proceedings, vol. ii. p. 30 (June, 1857).
Aphorism XXIII.
It is of the greatest importance that the Groups which give their substantive names to every included species should remain large.
It will be recollected that according to the Linnæan nomenclature, the genus is marked by a substantive, (as Rosa), and the species designated by an adjective added to this substantive, (as Rosa Alpina); while the natural orders are described by adjectives taken substantively, (as Rosaceæ), But this rule, though it has been universally assented to in theory, has often been deviated from in practice. The number of known species having much increased, and the language of Linnæus and the principles of Jussieu having much augmented the facilities for the study of affinities, botanists have become aware that the species of a genus and the genera of an order can be collected into intermediate groups 347 as natural and as well defined as the genera and orders themselves, and names are required for these subordinate groups as much as for the genera and orders.
Now two courses have been followed in providing names for these subordinate groups.
1. The original genera (considering the case of genera in the first place) have been preserved, (if well founded); and the lower groups have been called subgenera, sections, subsections, divisions, &c.: and the original names of the genera have been maintained for the purpose of nomenclature, in order to retain a convenient and stable language. But when these subordinate groups are so well defined and so natural, that except for the convenience of language, they might be made good genera, there are given also to these subordinate groups, substantive or substantively-taken adjective names. When these subordinate groups are less defined or less natural, either no names at all are given, and they are distinguished by figures or signs such as *, **, or § 1, § 2, &c. or there are given them mere adjective names.
Or, 2, To regard these intermediate groups between species and the original genera, as so many independent genera; and to give them substantive names, to be used in ordinary botanical nomenclature.
Now the second course is that which has produced the intolerable multiplication of genera in modern times; and the first course is the only one which can save botanical nomenclature from replunging into the chaos in which Linnæus found it. It was strongly advocated by the elder De Candolle; although in the latter years of his life, seeing how general was the disposition to convert his subgenera and sections into genera, he himself more or less gave in to the general practice. The same principle was adopted by Endlichen, but he again was disposed to go far in giving substantive names to purely technical or ill-defined subsections of genera.
The multiplication of genera has been much too common. Botanists have a natural pride in establishing new genera (or orders); and besides this, it is felt how useful it is, in the study of affinities, to define and 348 name all natural groups in every grade, however numerous they may be: and in the immense variety of language it is found easy to coin names indefinitely.