6 THE STUDY OF PLANTS 



certain ones of which the leaves instead of being curved 

 merely at the tip, as in the majority of black willows, are 

 "falcate" or curved throughout like a scythe blade. All 

 the individuals having this peculiarity are accordingly re- 

 garded as forming a distinct variety, and when we wish to 

 speak particularly- of these we use the name Salix nigra 

 variety falcnta. 



Cultivated varieties which are known, or supposed, to have 

 arisen in comparatively recent times, and show only minor 

 peculiarities, are commonly distinguished from varieties of 

 wild plants and from certain ver}' well-marked varieties in 

 cultivation by being named in English, French, or some 

 other modern language. Thus we speak of the "Baldwin" 

 and the "Spitzenburg" varieties of apple. As subordinate 

 kinds or subvarieties of cauliflower we have similarly the 

 "early .snowball" and the "autumn giant." 



The question as to whether a certain group of individuals 

 should be ranked as a species or as a variety is one which is 

 often difficult to decide, and different l)otanists sometimes 

 reach different conclusions. In all cases, however, a variety 

 is understood to he a group of individuals included within a 

 species and consequently connected with the other members of 

 the species by a series of intermediate forms. 



10. The genus. In the same way that those individuals 

 which possess some special .set of peculiarities constitute a 

 variety, and just as there may be several varieties in which 

 the individuals are enough alike to form a species, .so different 

 species possessing in common certain features of a more 

 general nature are grouped into a genus (plural genera).^ 



The name of the genus to which a given species belongs appears 

 as the first component of the botanical name. In the examples 

 already mentioned Gijpftophilo, Morus, Quercus, Salix, or Brassica 

 is the generic part; fastigiata, nlha, nigra, rubra, aquatica, or oleracea, 



' The beginner can hardly be expected to grasp more than vaguely 

 the distinctions here presented between genus, species, and variety; 

 and the same may be true as well of certain other distinctions to be con- 

 sidered presently. His conceptions are likely to grow more definite, 

 however, as his acquaintance with plants increases, and his efforts to 

 gain such wider acquaintance will be much facilitated by starting with 

 some conception, vague though it be, of what botanists mean by the 

 groups of different rank which they distinguish. 



