MONOCOTYLEDONS 263 



are called species. Therefore, a group of related species 

 forms a genus; and a group of related genera forms a family. 

 An acquaintance with the plants of a neighborhood should 

 begin by learning to recognize not merely important families 

 but also conspicuous and common genera and species. 



The technical name of a .plant is the combination of its 

 generic and specific names, the former always being written 

 first. For example, Quercus alba is the name of the com- 

 mon white oak, Quercus being the name of the genus to 

 which all oaks belong, and alba the specific name that 

 distinguishes this oak from other oaks. No other names 

 are necessary, as no two genera of plants can bear the same 

 name, and no two species of a genus can have the same 

 name. 



The so-called Manuals or Keys are books that contain 

 descriptions of plants, so arranged that one who knows 

 the meaning of the terms used can find the name of any 

 plant described. Ability to use such a manual is very 

 desirable to cultivate, for it is the most accurate and 

 effective method of forming a speaking acquaintance with 

 plants. 



156. Families of Monocotyledons. About forty mono- 

 cotyledonous families are recognized, containing numerous 

 genera and about twenty thousand species. Four fami- 

 lies will be selected, which include the great majority of 

 Monocotyledons; and these should be recognized at sight. 

 These families are conspicuous in numbers, or in appearance 

 or in usefulness; and for any or all of these characters they 

 deserve acquaintance. 



157. Grasses. The Grass Family (Graminece) is one of 

 the largest groups of plants. It is world-wide in its dis- 

 tribution, and is remarkable in its display of individual 

 plants, often growing so densely over large areas as to form 

 a close turf. 



The flowers are very simple having no calyx or corolla, 



18 



