6 



sysrKMATir rn m (>/.<><, y 



the tree, or the utaiii root in a syslrni (Fif^. 1). More com- 

 monly, especially in |)()niolo<rical subjects, the main root divides 

 early in the life of the |)lanl and is soon lost in its hranehes. 

 Early in the life of the tai)-root branches si)rin«r from it, similar 

 but thinner, which instead of frrowinnr downward extend almost 

 at riprht anprles to it; these are secoudar\i or hifrral roots. Fj-om 

 these and the lower part of the tap-root irrcfxular whorls of still 



smaller and much branched root- 

 lets form a network of fibrous roots. 

 All of these roots, collectively, make 

 up the root sj/stem. Some plants 

 have swollen more or less succulent 

 roots which contain stored up food ; 

 these are described as fleshy or tu- 

 herous, though the latter term is a 

 poor one as it suggests tubers which 

 are underground stems. The Vini- 

 fera grape is the only pomological 

 plant of temperate regions that 

 has fleshy roots. 



11. Adventitious roots. — In many 

 plants roots spring from the stem, 

 or from such modifications of it 

 as tubers, corms, rootstocks and 

 bulbs, or even from the leaves; all 

 roots that do not arise from seeds 

 or as branches of seed roots are adventitious (Fig. 2). The 

 roots of monocotyledonous plants, as the onions, lilies and 

 cereals, are mostly adventitious, growing out of lower nodes or 

 joints of the shortened stems. Many dicotyledonous plants, 

 among them some of the common fruits, are dependent for propa- 

 gation on adventitious roots. These differ little in appearance 

 from seed roots but are usually thinner and more fibrous. 



Quinces, dwarf apple stocks, gooseberries, currants, grapes, 

 and strawberries depend on the development of adventitious 

 roots as a means of propagation. Some cranberries, raspberries, 

 blackberries, and plums are so propagated and nearly all other 

 fruit-plants may be induced to throw out adventitious roots. 

 In general, with but few exceptions, any part of the stems of 



Fig. 1. Young cherry show- 

 ing root-system, stem, coty- 

 ledon and leaves. 



