120 PLANT LIFE ON THE FARM. 



seasonable growth of the plant using up the food intended 

 for his cattle or sheep, obviated. 



Plants cultivated for their foliage. Among these 

 are the various green crops and forage plants, cabbages, 

 mustard, clovers, sainfoin, lucerne, vetches and pasture 

 grasses. Apart from the special requirements of each par- 

 ticular plant, such as the special influence of nitrogenous 

 manures in promoting leaf-growth among grasses, and of 

 mineral manures in fostering the leafy development of legu- 

 minous plants, and the special demands made by particular 

 circumstances, the object, in all cases, is to ensure a rapid, 

 abundant and nutritious leaf-growth. In some cases where 

 otherwise too great acridity might be produced, it is desi- 

 rable to secure shade to the leaves, and thus prevent the 

 formation of the objectionable matters. Thus, in the case of 

 cabbages the grower prefers those which "heart" well, i.e., 

 those in which the leaves are tightly packed one over the 

 other, and do not readily separate ; and this tendency is 

 increased by constantly selecting for seed those varieties 

 in which this peculiarity is seen to be most marked. At 

 other times the production of objectionable secretions is 

 obviated by the process of " earthing up," as in the case of 

 celery, or by tying up the leaves as in lettuces. 



The development of leaves is of course largely dependent 

 on the well-being of the roots, so that, in a general way, all 

 those conditions of soil which are propitious to the develop- 

 ment of roots are so also to that of leaves. 



The requirements of particular plants are so varied, 

 according to their affinity and the very diverse modifica- 

 tions of form and structure presented by their roots, that 

 only generalities can here be alluded to. The cultivator 



