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TEXTBOOK OF BOTANY 



the sheath, there is a short, thin outgrowth. The blade 

 is long, drooping at the tip, narrow in proportion to its 

 length, and has a long, slender point. Its edge bears many 

 very fine teeth. On its upper surface a shallow groove 

 runs lengthwise above the midrib. The arrangement of 

 the veins looks quite unlike that in the bean leaf. Many 

 veins start from the base and run nearly parallel with one 

 another to the upper end of the leaf. The middle vein 

 (midrib) is much the largest. The midrib and the veins 

 that run parallel with it do not seem to be branched, as are 

 the veins in the bean leaf. There really are many slender 

 branch veins, which form a network ; but these interlacing 

 branches are so delicate that they are not easily seen, and 

 therefore the leaf is said to be parallel-veined. 



181. Roots. — The primary root does not become very 

 long. Early in the life of the young plant, other roots begin 

 to grow from the lower part of the stem (Fig. 103, C, D, E); 

 indeed, some of these roots were already present in the seed 

 as very small swellings upon the sides of the plumule. Both 

 the primary root and the roots that grow from the stem give 

 rise to fine branch roots. The mature com plant, there- 

 fore, has a cluster of slender branching roots (Figs. 97, 98) 



Fig. 98. — The root system of a corn plant at the time of flowering. 



