THE LATE OR MAIN-CROP VARIETIES 465 



development of the flowers and fruit. If flowers are needed 

 for hybridising purposes, plucking off the early-formed tubers 

 often produces the desired result. 



Varieties. — Considerable attention has been 

 paid to the improvement of the potato, and many 

 varieties are in existence differing in yield, ripening 

 period, shape, quality of tuber, and in many other 

 points. They may be classified in several ways, Fig. 146.— Trans- 



1 , 11 1 1 • ,■ . . verse section of 



but are usually placed in groups accordmg to their ovary of potato 



, • r • • ^1 ■ 1 1 flower, a Wall of 



time 01 ripening, their shape, or colour. ovary ; /placenta; 



The early varieties are consumed in an unripe 

 condition, and are adapted for forcing for early markets. To 

 this class belong Ashleaf, Beauty of Hebron, Snowdrop, Early 

 Regent, and others. 



The mid-season or second earlies are dug green for the 

 summer market, and may be left to mature with the later 

 varieties. Sir John Llewellyn, Reading Russet, British Queen, 

 and Windsor Castle belong to this class. 



The late or main-crop varieties ripen in autumn, and often 

 grow until cut down by frost. Abundance, Up-to-Date, Factor, 

 Duchess of Cornwall, King Edward VII. may be mentioned as 

 typical of this section. 



It is of little use to attempt to raise new varieties by selec- 

 tion of tubers only, as these are merely divisions of the parent 

 and cannot be expected to give rise to new offspring unless the 

 tubers chosen happen to be true bud-variations or 'sports.' 

 The latter are, however, of rare occurrence in the potato plant. 

 Marked variations are obtained in seedling plants, and it is from 

 these that selection is made in order to obtain new and im- 

 proved varieties. 



The chief points of a good variety are the following ; — 



(a) Strong disease-resisting power. 



(b) Good cooking quality ; when steamed or boiled, the 



tuber should break easily into a glistening floury condi- 

 2 G 



