The subject of palaeontological botany (see [Palaeobotany]) has been advanced by the researches of both botanists and geologists. The nature of the climate at different epochs of the earth’s history has also been determined from the character of the flora. The works of A.T. Brongniart, H.R. Goeppert and W.P. Schimper advanced this department of science. Among others who contributed valuable papers on the subject may be noticed Oswald Heer (1809-1883), who made observations on the Miocene flora, especially in Arctic regions; Gaston de Saporta (1823-1895), who examined the Tertiary flora; Sir J.W. Dawson and Leo Lesquereux, and others who reported on the Canadian and American fossil plants. In Great Britain also W.C. Williamson, by his study of the structure of the plants of the coal-measures, opened up a new line of research which has been followed by Bertrand Renault, D.H. Scott, A.C. Seward and others, and has led to important discoveries on the nature of extinct groups of plants and also on the phylogeny of existing groups.
Botany may be divided into the following departments:—
1. Structural, having reference to the form and structure of the various parts, including (a) Morphology, the study of the general form of the organs and their development—this will be treated in a series of articles dealing with the great subdivisions of plants (see [Angiosperms], [Gymnosperms], [Pteridophyta], [Bryophyta], [Algae], [Lichens], [Fungi] and [Bacteriology]) and the more important organs (see [Stem], [Leaf], [Root], [Flower], [Fruit]); (b) Anatomy, the study of internal structure, including minute anatomy or histology (see [Plants]: Anatomy).
2. Cytology (q.v.), the intimate structure and behaviour of the cell and its contents—protoplasm, nucleus, &c.
3. Physiology, the study of the life-functions of the entire plant and its organs (see [Plants]: Physiology).
4. Systematic, the arrangement and classification of plants (see [Plants]: Classification).
5. Distribution or Geographical Botany, the consideration of the distribution of plants on the earth’s surface (see [Plants]: Distribution).
6. Palaeontology, the study of the fossils found in the various strata of which the earth is composed (see [Palaeobotany]).
7. Ecology or Oecology, the study of plants in relation to each other and to their environment (see [Plants]: Ecology).
Besides these departments which deal with Botany as a science, there are various applications of botany, such as forestry (see [Forests and Forestry]), agriculture (q.v.), horticulture (q.v.), and materia medica (for use in medicine; see the separate articles on each plant).