Classification.—The more noteworthy ancient writers upon plants were Hip pocrates (460-357 B. C.) , Theophrastus (372-287 B. C.) , Pliny (23-79 A. n.), and Dioscorides of the 2d century. The 14th to the 17th centuries produced many botanists of a type known as herbalists, whose often ponderous works contain crude complications of the known sorts of plants, with hints of their uses. Dur ing this period the idea of genera among plants was evolved with greater and greater clearness. Linnaus was the first to give to each kind of plant known to him a double designation, consisting of a generic name followed by a specific name, thus: Rosa lucida, Viola pedata, Claytonia Virginiana, Claytonia Caro Unicorn.
The arrangement of families most gen erally followed during the 19th century has been that developed by the Genoese botanist, Auguste Gyrame De Candolle, and his son, Alphonse De Candolle. The De Candollean system received its most perfect exposition in the "Genera Plan tarum" of the two English botanists, George Bentham (nephew of Jeremy Bentham, the philosopher) and Sir Joseph Dalton Hooker, and was followed in all the systematic writings of Prof. Asa Gray. This system, while undoubtedly possessing great merit in its details, un happily fails to coincide with what is be lieved to be the historic sequence in which the different families have been evolved during past geological ages. It is, for this reason, rapidly giving place to a more philosophic system, elaborated by the German botanist, A. W. Eichler (1839-1887) and subsequently developed with great perfection in an extended work upon the "Natural Families of Plants" prepared under the editorship of Professors Engler and Prantl. The
system, embracing all plants, begins with the simplest cryptogams and ends with the composite, the great family, to which belong the golden rod, aster, thistle, and dandelion.
The subject of vegetable physiology, al though dating its beginnings from the observations of Stephen Hales (1677 1761) upon the movement and pressure of sap, made but little advance before 1850. It was from that time greatly stimulated by the acute observation and close reasoning of Charles Darwin in England, and Prof. Julius von Sachs in Germany. Subsequent leaders in this line of investigation have been W. Pfeffer and Edward Strasburger. Anatomical botany is greatly indebted to Anton de Bary. The most meritorious works upon botanical geography, a subject which treats of floral conditions and the dis tribution of the plants in different coun tries, have been those of A. H. R. Grisebach, Adolph Engler, and A. F. W. Schimper.
The rapid growth of agricultural col leges in this country, fostered by Gov ernment and State aid, has given a great impulse to the study of botany. That branch of it which concerns itself with the diseases of plants, called pathol ogy, has been carried to a point of ef ficiency not yet reached in any other country. The methods of American bot anists have caused systematic botany or taxonomic botany to register great advances during the two decades of the present century. There is now under way a complete revision of North Ameri can flora in the light of the geographic relationships of plants. Future progress is likely to be based on the principles of heredity in plants and the correlation of plant functions with plant structure.