Part 85. The linnsean system. The great need for some system which would be used by botanists in general, could, of course, be met only by a classification that was more convenient than any of those already proposed. Linnaeus was the first to see clearly that the necessary convenience could not be expected in his day from any attempt at a natural arrangement, for the plants to be arranged were as yet very imperfectly known. His predecessors had tried to produce a natural classification on an artificial basis, with results that were neither natural nor convenient. He aimed first of all at convenience, and to this end adopted a frankly artificial basis; yet in spite of this, as we shall see, his system proved to be more natural in many ways than any previously proposed.

In the Linnaean system, the old division into herbs and trees was entirely abandoned; all plants were divided into twenty-four "classes," according to the presence, number, or form of certain essential parts (pistils) of the flower; and these classes were so grouped that all flowering plants were separated from those which have no true flowers. The latter constituted Class 24, Cryptogamia1 or cryptogams, which includes all plants such as seaweeds, mushrooms, mosses, and ferns, that are either destitute of parts such as we find in flowers, or if anything corresponding to such parts are present they are hidden from our unaided sight. The other twenty-three classes include all plants in which floral parts essential to the formation of seed, are manifest,-such plants as are now often known as Phenogamia 2 or phenogams. Each class was again divided into several "orders" mostly according to the number, etc., of the other essential organs (stamens) of the flower. Under these orders Linnaeus grouped all the genera and species of plants known in his day.

1 Cryp-to-ga'-mia - Gr. kyryptos, hidden.

2 Phe-no-ga'-mi-a (written also Phaenogamia and Phanerogamia) - Gr. phaino, to be manifest; gamos, marriage: because the floral organs essential to the production of seed are manifest.

The distinctions upon which Linnaeus depended were so easy to understand and remember, and afforded such a convenient means of classifying any plant, that the system soon gained an immense popularity, especially in England, and led to a widespread study of plants. Moreover, in his time, explorations in various parts of the world were bringing to light a great many kinds of plants and animals, previously unknown; and as Linnaeus had also published a convenient classification of animals, most of those new discoveries were sent to him to name and classify. On the foundations so broadly laid systematic botany progressed much more rapidly and better than ever before, and during more than half a century the system of Linnaeus remained practically the only one in use.

We have said that although deliberately artificial, the Linnaean system was remarkably natural in many respects. This is shown in the separation of the cryptogamic from the phenogamic plants; also in the fact that the species of a genus were always kept together, and in the association of many of the genera into orders corresponding to certain of the families recognized to-day.

To understand why this is, we must remember that plants which resemble each other in one particular have very generally other points of resemblance as well; hence, almost any artificial system is bound to be natural to some extent, and to what extent will depend on how far the characters chosen imply other points of resemblance. The reason why the Linnaean system was so natural, was that its founder had the sagacity to choose his characters primarily from the essential parts of the flower; for likeness in these parts involves a great deal of similarity in other respects. Thus, the possession of true flowers implies the formation of seeds, and this in turn generally involves an elaborateness of structure in the plant as a whole far greater than is found in cryptogamic plants, which, as we know, lack true flowers and seeds; while among flowering plants it constantly happens (as the reader has doubtlessly already noticed in such familiar examples as the apple, pear, and quince) that close resemblance in the form of the seed-producing parts of the flower goes with fundamental similarity in all other parts of the plant.

With all these advantages it is no wonder that this remarkable system should have exerted the wide influence which it did; but after all it was too artificial to serve permanently as a final solution of the great problem of systematic botany. Thus, for example, the group with two stamens and one pistil includes such widely different plants as olive and sage, while sage is kept far removed from other mints because they have four stamens. No one realized more fully than Linnaeus that his system was at best but a makeshift, fit only to serve the temporary needs of the science until botanists should be more extensively and more thoroughly acquainted with plants than would be possible for many years to come; and he regarded his work only as a stepping-stone to the final achievement of an adequate classification.