666 



SCIENTIFIC RECREATIONS. 



the plant, and it is then carried by tubes to the root, and so on throughout 

 the plant, and with air ducts serve to keep the plant alive. 



The stem emanates from the plumule, and in 

 a short time little knots develop upon it, which 

 are the incipient leaves. The knots are divided 

 into nodes and internodes, because they appear 

 on different sides of the stem and intermediate, so 

 as to alternate with each other, and are really buds. 

 The issues unite also into leaf-stalks or petioles, 

 and extend into the leaf-frame or skeleton as we 

 see it when the leaf has decayed. So thus we 

 have an upward and a descending growth, which 

 respectively constitute the stem and root of a 

 flowering plant. 



Some trees have roots growing from the stem, 

 as* in the banyan tree, and roots can produce 



Fig. 752. Tuberous (fasciculated) root. J 



stems as well as the latter can form roots. The 



uses of roots are so well understood that we need not particularize them. In 

 many trees we find what are termed lenticella, like holes in the bark. These 

 fissures will put forth roots under favourable circumstances. These stem 



Fig- 753. Banyan tree. 



roots are called adventitious, and by taking "cuttings" from plants we 

 make good use of them for propagation. 



But there are underground stems as well as those which flourish and 

 climb above it. "Bulbs" and "tubers" are common instances of these 

 underground stems, or "rhizoma," which are horizontal. The ordinary stems 



