STEMS 



79 



Jblu. 47. Bulb of Hyacinth. 

 (Exterior view and split lengthwise.) 



however, a good many cases in which the stem takes on 



a more strikingly leaf-like form. The common asparagus 



sends up in spring shoots 

 that bear large scales which 

 are really reduced leaves. 

 Later in the season, what 

 seem like thread-like leaves 

 cover . the much-branched 

 mature plant, but these 

 green threads 

 are actually mi- 

 nute branches, 

 which perform 

 the work of 



leaves (Fig. 50). The familiar greenhouse 



climber, wrongly known as smilax (properly 



called Myrsipliyllum), bears a profusion of 



what appear to be delicate green leaves 



(Fig. 51). Close study, however, shows that 



these are really short, flattened branches, 



and that each little branch springs from 



the axil of a true leaf, ?, in the form 



of a minute scale. Sometimes a flower 



and a leaf-like branch spring from the 



axil of the same scale. 



1 Branches which, like those of Myrsi- 



phyllum, so closely resemble leaves as to 



be almost indistinguishable from them are 



called cladophylls. 



94. Modifiability of the Stem. The stem may, as in the 



tallest trees, in the great lianas of South American forests, 



sea 



FlG. 48. Longitu- 

 dinal Section of 

 an Onion Leaf. 



sea, thickened base 

 of leaf, forming a 

 bulb-scale; s,thin 

 sheath of leaf ; bl, 

 blade of the leaf ; 

 int, hollow inte- 

 rior of blade. 



