DIVISION OF LABOR 



175 



perature, and sunlight, the 

 seedlings that develop will 

 each differ one from an- 

 other in a slight degree.^ 

 But in a general way they 

 will have many characters 

 in common, as the shape 

 of the leaves, the posses- 

 sion of tendrils, form of 

 the flower and fruit. A 

 species of plants or animals 

 is a group of individuals so 

 much alike in their char- 



A colony of trilliums, a flowering plant. 

 (Photograph by W. C. Barbour.) 



acters that they might have had the same parents. Individuals of 

 such species differ slightly ; for no two individuals are exactly alike. 



Species are grouped to- 

 gether in a larger group 

 called a genus. For ex- 

 ample, many kinds of peas 

 — the wild beach peas, the 

 sweet peas, and many 

 others — are all grouped in 

 one genus (called Lathyrus, 

 or vetchling) because they 

 have certain structural 

 characteristics in common. 

 Plant and animal genera 

 are brought together in still 

 larger groups, the classifica- 

 tion based on general like- 

 nesses in structure. Such 

 groups are called, as they 

 become successively larger, 



Rock fern, polypody. Notice the underground 

 stem giving off roots from its lower surface, 

 and leaves (C), (S), from its upper surface. 



Family, Order, and Class. Thus both the plant and animal king- 

 doms are grouped into divisions, the smallest of which contains 



1 Note to Teachers. — A trip to the Botanical Garden or to a Museum should 

 be taken at this time. 



