ROOTS AND THEIK FUNCTIONS. 37 



a form of bud from which spring up, in some instances, 

 stout stems, bearing a cap containing fruit-like organs ; 

 while in others there is only a very minute ascending 

 axis. 



While authors differ very widely in their opinions as 

 to what part of certain plants should be considered as 

 roots, and what should not, nearly all agree that what- 

 ever is developed ^ejw^the^cotyledons, figure 13, .ojrjirst 

 pair of seed-leaves, in dicotyledonous plants, should at 

 first be considered as the root, or descend- 

 ing axis ; but this part soon undergoes a 

 change, or outgrows its normal functions, 

 and becomes merely an extension of the 

 true stem or ascending axis. The embryo 

 root, no doubt, when it first pushes out 

 from the seed, absorbs nutriment from the 

 elements with which it is surrounded, just 

 as the smaller rootlets do later in the life 

 of the plant ; but when this main or cen- 

 tral root ceases to absorb nutrients it would 

 be difficult to determine. The stem or 

 ascending axis, and the two cotyledons 

 (seed-leaves), with a central terminal bud 

 or leaf (plumule) is that part of the plant 

 which seeks the light and air ; while the ING COTYLEDONS. 

 part growing in the opposite direction, or downward, is 

 the root or descending axis or radix. In many of the 

 monocotyledonous plants (one cotyledon or seed-leaf), like 

 the Grasses, Asparagus, Yuccas, Palms, etc., there are a 

 number of roots, or a multiplication or division of the 

 radix from the first, and, in some instances this emission 

 of what may be properly called adventitious roots appears 

 to be the normal habit. 



But these rather anomalous characters need not sur- 

 prise the propagator of plants if he will keep in mind 

 that variation is a rule of nature ; and while there is suf- 



