326 



LESSONS WITB PLANTS 



often have a distinct central pith, which some- 

 times disappears, leaving the stem hollow. The 

 parts of the flowers are most com- 

 monly in fives or fours, and the leaves 

 are, for the most part, distinctly 

 netted-veined. 



397a. Dicotyledonous plants oomprise all the 

 irees o£ northern countries, and such tribes as 

 the mustards, legumes, roses, composites, cacti, 

 pigweeds, honeysuckles, and the orchard fruits of 

 the North. In some eases there are more than 

 two cotyledons. 



398. The monocotyledonous plants, 

 on the other hand, increase in diam- 

 eter by means of new woody bun- 

 dles scattered in the stem, and there 

 may be no distinct and separable bark, 

 as there is in the dicotyledons; they 

 are, therefore, sometimes called endo- 

 gens ("inside growers"). The flowers 

 are built mostly upon the plan of 

 three (220a), and the main veins of 

 the leaves are generally essentially parallel to each 

 other (but the secondary veins are usually inter- 

 woven or netted). As a rule, the leaves do 

 not fall away with a clean scar, as they do in 

 the dicotyledons, a point which we have already 

 discovered (39a). 



FiQ. ,347. 



(termination com- 

 pleted. 



