70 THE TREE BOOK 



accommodate themselves in their close quarters. 

 Little walnut and hickory plantlets cannot lift 

 their fat, heavy seed-leaves above ground. 

 Their shoots rise straight into the sunshine, till 

 they are well above the surrounding plants and 

 herbs, and their first three or four pairs of 

 leaves are mere scales. They do not need to 

 put their earliest strength into making leaves as 

 most seedlings do, for they have a good supply 

 of food in their buried "pantries." 



Seed-leaves are called cotyledons. They are 

 in truth little storage plants, and their sole busi- 

 ness is to nourish the seedling until it is ready 

 to support itself. The walnut and hickory coty- 

 ledons are typical of most of the nut seed-leaves. 

 They are so heavily stored with nourishment 

 that they are quite unfit to act as leaves, and so 

 never make their appearance above ground. 

 .Most seedlings, however, push up their seed- 

 leaves, and these do service until the real leaves 

 have developed and are ready for action. 

 When they are no longer needed, the cotyledons 

 shrivel and drop off. The majority of tree 

 seedlings are di-cotyledonous, that is they have 

 two cotyledons or seed-leaves. The pine fam- 

 ily are exceptions. Their little seedlings boast 

 many seed-leaves, and so are poly-cotyledon- 

 ous. 



