STRUCTURE OF MONOCOTYLEDONOUS STEMS 187 



Structure of Monocotyledonous Stems 



The most useful of the Monocotyledons are the Grasses of 

 which the Bamboos are the largest representatives. The Lilies, 

 Asparagus, and Palms are some other Monocotyledons that are 

 familiar. Nearly all Monocotyledons are herbaceous, although 

 there are a few, notably the Palms and Bamboos, that are woody. 



The characteristic arrangement of the tissues of monocotyle- 

 donous stems, as they appear to the naked eye, can be seen in the 



FIG. 165. -Cross section of a Corn stem, a, rind; v, vascular 

 bundles; p, pith; e, epidermis. After Hayden. 



cross section of a Corn stem, as shown in Figure 165. In this sec- 

 tion three features are prominent. First, there is the rind-like 

 portion, forming the outer region of the stem and affording pro- 

 tection and strength. The cells of this outer region contain 

 chlorophyll and also function to some extent like leaves in the 

 manufacture of food. Second, there is the pith, left white in our 

 drawing and filling the entire cavity within the rind. Third, there 

 are the vascular bundles (shown by dots) which, although scattered 

 throughout the pith, are more numerous near the rind, thus tend- 

 ing to form a hollow column, which, as previously pointed out, is 

 the best arrangement for strength. In monocotyledonous stems 

 the tissues are run together and consequently are not so grouped 



