Part 86. The natural system. As a contribution to the natural system which he firmly believed would be developed in course of time, Linnaeus published a series of sixty-seven groups of genera which he called "natural orders." He confessed his inability to define these groups by giving characters which would apply to all the genera of an order, and at the same time serve to separate the orders one from another; and left it for future botanists to discover how far the groups he had suggested really express the fundamental resemblances and differences found in nature. The fuller knowledge of later times has largely justified a good share of these groupings; not a few of Linnaeus' natural orders are substantially equivalent to families recognized to-day, and have a place in modern classification often under the same or similar names. As examples may be mentioned the Palmoe or palms, Gramina or grasses, Orchideoe or orchids, Compositoe or composites, Coniferoe or conifers, and Filices or ferns.

During the life-time of Linnaeus, the only other important attempt at a natural classification was made by Bernard de Jussieu, of France, who was a correspondent of Linnaeus, and was in charge of the royal botanic garden at Trianon. Here he grouped the plants as far as he could in natural orders, but he published nothing. In 1789, two years after the death of Linnaeus, Antoine Laurent de Jussieu, nephew of Bernard, published a classification of genera under natural orders, one hundred in number. These were carefully defined by suitable characters, and thus constituted the first thoroughgoing attempt at a natural system. Not only were the genera grouped into well-defined orders, but the attempt was made to group the orders into higher and higher series, expressive of their degrees of likeness.

On the foundation thus laid over a century ago the natural system now in general use has been slowly developing; the work of improvement is still going on, and more rapidly than ever before. Eventually the science of botany may boast of a systematic classification founded upon, and, in a way, expressing, a full knowledge of vegetable forms. Yet, as we shall hope to show in a future chapter, there are good reasons for believing that such an ideal classification will embody in very large part the distinctions at present recognized, or in other words, that the main features of a truly natural system are fairly well established. The next generation of botanists will doubtless have the advantage of a far better classification, especially of cryptogams, than that in use to-day; but we may well believe that their classification will be essentially the same in general principle and in its main features as that now used. To develop the present system has been a gigantic task, beset with many difficulties; and before we can rightly understand the outcome of all this botanical labor, we must consider still further the difficulties overcome. Until we have mastered certain of these ourselves we are not fitted either to appreciate or to use to best advantage the important results which botanists have achieved in systematic classification.