THE NATURAL SYSTEM. 67 



A Ge7ius (plural genera) comprises a number of species 

 having points of resemblance. Example : — Rosa. 



A Species is a plant belonging to a genus resembling the 

 plants that produced it, and bearing seed from which 

 similar plants spring. Example : — Burnet rose (Rosa 

 spinosissima). The apple and pear are separate species of 

 the genus Pyrus ; the plum and apricot of the genus Prunus. 



A Variety is a plant which by the influence of soil, 

 climate, or cultivation changes in shape, colour, taste of 

 fruit, or otherwise. Varieties (or hybrids) cannot be 

 depended on to reproduce similar plants from seed, as 

 they have a tendency in successive generations to return to 

 the original stock. Some, however, are consistent, produc- 

 ing seed from which spring plants resembling the original. 

 These are termed Races. Wheat and other cereals are 

 races. 



Thus, we should say : — Scotch roses are varieties of the 

 Burnet rose, which is a species of the genus Rosa, belong- 

 ing to the order or family of Rosacea, in the class of 

 Dicotyledons. 



Under the Natural System plants are arranged according 

 to the relative and subordinate importance of their different 

 organs ; whereas the Linnsean System is based upon an 

 examination of the flowers only. The three great divisions 

 already explained are further subdivided according to the 

 disposition of these organs. Hence while the student, from 

 the instruction already given, should be able to discriminate 

 between dicotyledons, monocotyledons, and acotyledons, 

 he must search under those several heads for the family to 

 which a specimen belongs. It would be impossible in a 

 work like the present to attempt even an outline of these 



