1 7 o AGRICULTURAL BOTANY 



the seed plants. The first three divisions include such 

 plants as are represented by bacteria, molds, mildews, 

 rusts, mushrooms, yeasts, mosses, and ferns. Many of 

 the plants in these divisions are of great importance in 

 agriculture, but, except mushrooms, none of them is 

 raised by the farmer as a food crop. 



Seed plants include all the great families that goto 

 make the crops of the farm. 



They may be divided into two subdivisions. Those 

 having their ovules naked, that is, not inclosed in an 

 ovary, are called Gymnosperms. The pine family, in- 

 cluding a large number of the evergreens, belongs here. 



Those having their ovules inclosed in an ovary are 

 called Angio sperms. The Angiosperms are again di- 

 vided into two classes, depending on the number of 

 cotyledons, or seed leaves, in the seed. Those Angio- 

 sperms having one cotyledon are called Monocotyledons 

 or Endogens. Besides being distinguished by having 

 but one cotyledon, monocotyledons have usually par- 

 allel-veined leaves and usually have parts of their 

 flowers in threes, never in fives. The corn plant is a 

 good illustration of a monocotyledon. 



Note. An earlier classification of plants makes two great divisions: 



f The algze and fungi and their allies. 

 I. Cryptogams ] The liverworts and mosses. 



[ The ferns, horsetails, and club mosses. 

 II. Phanerogams The seed plants. 



Angiosperms having two cotyledons in the seed are 

 called Dicotyledons or Exogens. They usually have 

 netted-veined leaves, and the parts of their flowers in 

 fives. Each of these subclasses is divided into numerous 

 families or orders, about one hundred of which are 



