292 INTRODUCTION 



of the divisions end in -phyta, commonly written -phyte, from 

 the Greek word phyton which means plant. The names of classes 

 commonly end in -ineae or -eae and are usually derived from some 

 important group included. Thus the Lycopodineae is the class 

 containing the Lycopods, and the Filicineae is the class contain- 

 ing the Ferns. 



The names of orders end in -ales, and orders are commonly 

 named from some prominent family included. Thus the Resales 

 are named from the Rosaceae, the Rose family. Names of families 

 usually end in -aceae and are commonly derived from some 

 prominent genus, as for example the Liliaceae, which is the Lily 

 family. The names of genera are Latin nouns in the nominative 

 case. Thus Quercus is the Oak genus, Pyrus, the Apple genus, 

 and Acer, the Maple genus. Species have two names, the name 

 of the genus and the name that distinguishes the species. For 

 example, Quercus alba is the White Oak, while Quercus rubra is 

 the Red Oak. Quercus is the name of the genus, and the terms 

 alba (the Latin term for white) and rubra (the Latin term for red) 

 name the species. In English we simply change the terms about 

 and say White Oak instead of Oak White. 



The Divisions of the Plant Kingdom. The phylogenetic 

 divisions of the Plant Kingdom arranged in phylogenetic 

 order are Thallophytes, Bryophytes, Pteridophytes, and Spermato- 

 phytes. 



The Thallophytes are the simplest plants and are regarded as 

 the lowest and most primitive from the standpoint of evolution. 

 The word means thallus plants. As previously stated the 

 ending -phyte always means plant. Thallus refers to the fact 

 that the plant body has a simple organization. It is not differen- 

 tiated into roots, stem, and leaves. Bacteria, Toadstools, and 

 Algae are familiar Thallophytes. The plant body of some of 

 them consists of a single cell, which is the simplest plant body 

 possible. 



The Bryophytes are so named because they are chiefly Moss 

 plants. Besides the Mosses, they also include the Liverworts. 

 The Bryophytes have better organized plant bodies than the 

 Thallophytes and are, therefore, considered higher in the scale 

 of evolution. 



The Pteridophytes are so named because they include the Fern 

 plants. Most Pteridophytes are Ferns, but this group includes 



