26 



SEEDLINGS. 



[section 3. 



the cereal gi;iiiis) it raises the comparalively liglit seed iuto the air, the 

 tip still reuiamiug in the seed aud feeding upon the albumen. When 

 this food is exhausted and the seedling is well es- 

 tablished in the soil, tlie upper end decays and the 

 emptied husk of the seed falls away. 



43. In Maize or In- 

 dian Com (Fig. 66-70), 

 the embryo is more de- 

 veloped in the seed, and 

 its parts can be made out. 

 It lies against the starchy 

 albumen, but is not 

 enclosed therein. The 

 larger part of it is the 

 cotyledon, thickish, its 

 edges involute, and its 

 back in contact witli the 

 albumen ; partly enclosed 

 by it is the well-devel- 

 oped plumule or bud 

 ■wiiich is to grow. For 

 the cotyledon remains in 

 the seed to fulfil its office 

 of imbibing nourishment 

 from the softened albu- 

 men, which it conveys to 

 the growing sprout ; the 

 part of this sprout which is visible is the first leaf of the plumule rolled up 

 into a sheath and enclosing the rudiments of the succeeding leaves, at the 

 base enclosing even the minute caulicle. In germination the first leaf of 

 the plumule develops only as a sort of sheath, protecting the tender parts 

 within; the second and the third form the first foliage. The caulicle never 

 lengthens: the first root, which is formed at its lower end, or from any 

 part of it, has to break through the enclosing sheath ; and succeeding roots 

 soon spring from all or any of the nodes of the plumule. 



44. Simple-stemmed Plants are thus built up, by the continuous pro- 

 duction of one leaf-bearing portion of stem from the summit of the preced- 

 ing one, beginning witii the initial stem (or caulicle) in the embryo. Some 

 Uicotyls and many Monoootyls develop only in this single line of growth (as 

 to parts above ground) until the flowering state is approached. For some 

 exani[)les, see Cycas (Fig. 71, front, at the left) ; a tall Yucca or Spanish 

 Bayonet, and two Cocoa-nut Palms behind ; at the right, a group of Sugar- 

 canes, and a Banana behind. 



Fig. 71. Simple-stemmed vegetation. 



