Ch. IV, 4; 



DEVELdFMKXT OF STEMS 



13.5 



anatom}- are very stable in heredity, thu? making them good 

 guide- to the evolutionary hi-tory and present relationships 

 of plants. This important pha-e of investigation is now in 



) r~, 



Fig. S9. — A single bundle in Corn (one from those shown in Fig. 7-i), 

 in cross section ; X 130. .s points to the strand of phloem : m and sp are 

 ducts which, with the intermediate cells, form the xjdem : Ms an air space 

 containing a ring, a. from a duct : ig indicates the sheath around the bundle. 

 (From .Strasburger.) 



active and successful development, but is somewhat too 

 special in method for further consideration in an introduc- 

 torv course. 



4, The Developmext of Stem.s .\xd Leaves from Bitds 



Stems and leaA'es originate together in buds, though it is 

 more exact to say that the embryonic condition of a stem 

 with its leaves constitute- a lnud. 



Alost familiar of all are the ■ndnter buds of trees, in which 

 the bud proper is en'wTapped -nithin corky brown scales, 

 often -ft-ith accessory Hnings of hairs or coatings of resin, as 



