1 4 INTRODUCTION. [13. 



accustom himself early to the use of the more accu- 

 rate names employed in science. 



26. The Latin name of a plant is always double 

 generic and specific. Thus Fragaria is generic, or the 

 name of the genus of the plant vesca is specific, or 

 the name of the species. 



27. A Species embraces all such individuals as 

 may have originated from a common stock. Such 

 individuals bear an essential resemblance to each other 

 as well as to their common parent, in all their parts. 

 For example, the White Clover (Trifolium repens) is a 

 species embracing thousands of contemporary individ- 

 uals scattered over our hills and plains, all of common 

 descent, and producing other individuals of their own 

 kind from their seed. 



28. To this law of resemblance in plants of one 

 common origin there are some apparent exceptions. 

 Individuals descended from the same parent often 

 bear flowers differing in color, or fruit differing in 

 flavor, or leaves differing in form, etc. Such plants 

 are called Varieties. They are rarely permanent, often 

 exhibiting a tendency to revert to their original type. 

 Varieties occur chiefly in species maintained by culti- 

 vation, as the Apple, Potato, Rose, Dahlia. They also 

 occur more or less in native plants (as Hepatica tri- 

 loba), often rendering the limits of the species ex- 

 tremely doubtful. They are due to the different cir- 

 cumstances of climate, soil, and culture to which they 

 are subjected, and continue distinct until left to mul- 

 tiply spontaneously from seed in their own proper soil, 

 or some other change of circumstances. 



29. A Genus is an assemblage of species closely 

 related to one another in the structure of their flowers 



