22 



THE PH^NOGAMIA HOW DEVELOPED. 



CHAPTEE III. 



THE PH^NOGAMIA HOW DEVELOPED. 



103. The embryo. The plant in its earliest stage of life is an em- 

 bryo, contained in a seed. It then consists essentially of 

 two parts, the radicle and the plumule. We may discern 

 both in many seeds, as the pea, bean, acorn. 



104. Growth of the embryo. After the seed begins 

 to grow or germinate, the embryo extends itself in two 

 directions, to form the axis of the plant. The radicle or 

 root-end grows downward, penetrating the dark damp earth 

 as if to avoid the light, and forms the root or descending 

 axis. The plumule, taking the opposite direction, ascends, 

 seeking the light, and expanding itself as much 

 as possible to the influence of the atmosphere. 

 This constitutes the stem or ascending axis, 

 bearing the leaves. 



105. Growth of the terminal bud. 

 first the ascending axis is merely a hud, 

 that is, a growing point, clothed and 

 protected by little scales, the rudiment- 

 ary leaves. As the growing point ad- 

 vances, and its lower scales gradually 

 expand into leaves, new scales suc- 

 cessively appear above. Thus the 

 axis is always terminated by a bud. 



106. Axillary buds. By the 

 growth of the terminal bud the 

 axis is simply lengthened in one 

 direction, an undivided stem. 

 But besides this, buds also 

 exist, ready formed, in the 

 axils of the leaves, one in 

 each. 



107. How BRANCHES 



ARE FORMED. Thcsc axil- 

 lary buds, a part or all of them, may grow and develop like the ter- 

 minal bud, or they may always sleep, as in the simple-stemmed mullein 

 or palm. But in growing they become branches, and these branches 



Acorn (seed of Quercus pahut- 

 </'i«) germinating ; 6, section sliow- 

 ing the ratliclo (r) which is to be- 

 come thft root, and the two cotyledons (c) which are to 

 nourish it; 7, the radicle r, descending ; 8 and 9, tlie 

 radicle, »', descending, and the pluuiule (p) ascending. 



