132 RELATK >NSHIP < >F PLANTS 



ciated with outgrowths thai appear ;i- the burr in the chestnut 



and beech an<l a> a cup in the oak. On accounl of these and 

 other common characteristics these genera are supposed to be 

 related and arc therefore grouped together in one family. A 

 family is composed of allied or related genera. The name of 

 the family is derived from some characteristic genus in the group. 

 In this case ii happens to be the beech or Fagus. To distinguish 

 a family from a genus the termination oceae is added to the base 

 of the generic word, in this example making the family name 

 Fagaceae. So we have the three allied genera, oak. beech, and 

 chestnut forming the beech family or Fagaceae. In the same 

 way it will he found that families are related and joined to- 

 gether into a still larger group known as the order. The flowers 

 of the birch, alder, water heech, and ha/el genera are very simi- 

 lar and consequently form a family known as the birch family or 

 Betulaceae, Betula being the name of the lurch genus. It will 



also he noticed that there is a similarity between the flowers of 



the Betulaceae and Fagaceae. This relationship is expressed by 



placing them in the same order known as the heech or Fagales, 



the termination ales being employed to distinguish the order just 



as aceae characterized the family. So also orders are related 

 and grouped into classes. For example, the Fagales and many 

 other orders are characterized by having seeds with two cotyle- 

 dons. Several other orders have seeds with hut one cotyledon. 

 This relationship is expressed by grouping the orders into two 

 classes, Dicotyledones and Monocotyledones. In both of these 



classes the seeds are inclosed within the pistil, hut in the cone hear- 

 in- trees tin- seeds are exp< »sed i m a flat scale-like « >rgan. All seeds 



producing plants belong to one or the other of these two -roups. 



So we have two subdivisions, the A.ngiospermae, meaning seeds 

 inclosed, and the Gymnospermae, meaning naked seeds. If 

 now we Btop to consider Mill larger groups than subdivisions, 

 it will he noted that man) plants do not produce seeds, as in the 



nis and mo- So a final grouping of plants 



into divisions or subkingdoms ma) he made. All seed bearing 

 plants form the division Spermatophyta, meaning seed plants; 

 the ferns comprise the division Pteridophyta, meaning fern plants. 



