CLASSLFICATION. The general classification most in use among botanists at present, though doubtless to be mollified very soon, is as follows: The plant kingdom is divided into four great fundamental groups: (1) Thallophytes (Alga• and Fungi) : (2) Bryophytes (Liverworts and Mosses) ; (3) Pteridophytes (Ferns. Horsetails, and Club-mosses) ; and (4) Spermatophytes (Gynmosperms and Angiosperms). The Thal lophytes, as at present constituted, doubtless represent several groups coordinate with the other great groups: and probably the gymno sperms and angiosperms are each to be regarded as worthy of first rank. In any event, the general categories have become fairly well es tablished. The subordinate classification of an giosperms is of most general interest, as the group comprises the most conspicuous and best known forms, the true flowering plants. The two great subdivisions are Monocotyledons (grasses, palms, lilies, orchids, etc.) and Dicoty ledons (the ordinary trees, buttercups. roses, peas. heaths, mints. sunflowers, etc.). The over whelmingly large assemblage is the Dicotyledons, which are new grouped under two heads: (I) Arehichlarnydew, with calyx or corolla lacking or of distinct parts; and (2) Sympetah•, with corolla present and its petals more or less united.
All subordinate classification is constantly shifting, in order that it may keep step with the very rapidly aecumulating body of morpho logical data: for Classification. or Taxonomy, as it is more technically styled, must include the last expression of our knowledge of plants,.
.1botruous; Y. While the historic stand point taxonomy (classification) deserves first mention, probably the most fundamental sub of botany is Morphology, which treats of the structures of plants and their development, and upon whose data taxonomy must build. There was an older morphology which dealt mere ly with the forums of mature plants and their organs, and whose conception of organs was that everything about a plant could be referred to a very few categories, the favorite ones being root, stem, and leaf. Under this belief, every structure which was not evidently root, stem, or leaf was disguised, and the business of morphology was to strip off these disguises and reveal the real nature of the structure. This phase of morphology was dominated by Goethe's doctrine of metamorphosis—a doctrine which has been a serious impediment to botanical progress.
The present morphology, however, concerns it self more with the development of structures than with the mature forms, a point of view which dates at least from Hofmeister'selassic re searches of IS51. It is essentially an embryologi cal subject, therefore, whose purpose is to dis cover from developing structures every possible suggestion as to the relationships and origin of great groups. In such study the life-history of a plant is traced from the single cell with which it starts to its mature form, and this life histo•y at more than one point may give sug gestions of relationships. To develop a plant through all of its individual history, or to obtain all the stages ill the history of some kind of plant, is a long and difficult piece of work. When this is done for the hundreds of thousands of species of plants recorded, morphology will be in a position to supply the data for a real and relatively permanent classification.
At the present stage of morphological progress, however, large problems, such as the origin of the great groups, still confront us. In a general way, morphologists may he said to agree to the following statement: The represent the most primitive known forms from which the higher plants may be said to have been derived. The fungi are largely regarded as degenerate algae, which have made a certain amount of progress, but have developed no higher groups. The algae, therefore, represent the great ances tral group, and directly from them the liver worts seem to have arisen. The liverworts have certainly given rise to the mosses, and many claim that they have also given rise to the ferns. It certainly seems true that the ferns have come either through the liverworts or directly from the algte. Whatever may be the origin of the ferns. they have undoubtedly given rise to the seed-plants ( flowering plants). Just what seed-plants have come from what fern plants is a matter of discussion at present, but it is probable that several lines of seed-plants have arisen from as many branches of the fern stock. For a fuller statement of the modern development of morphology, see the articles AL TERNATION OF GENERATION and TIETEROSPORY.