ENDOGENS. Cl 



the leaves, flowers, and fruit. Some plants are ap- 

 parently stemless, from tins part remaining very 

 short and undeveloped in proportion to the roots and 

 leaves, as in the primrose. The woody stem or ti*unk 

 characterizes trees and shrubs. A simple unbranchcl 

 trunk, as the palm, is called a candex. The scape >s 

 a leafless stem bearing only flowers, and belonging to 

 a so-called stemless plant. It may bear only a single 

 flower, as the tulip, or several, as the hyacinth and 

 lily of the valley. Sometimes stems send out run- 

 ners or branches which run above the ground, and 

 Bend out adventitious roots from their nodes or ex- 

 tremities which develop perfect plants, as the straw- 

 berry. The rhizome is an under-ground stem, send- 

 ing up branches into the air. The tuber is a thick- 

 ened, fleshy under-ground stem, as the potato, in which 

 we may find buds or eyes concealed in depressions. 

 The lull) is also fleshy, but has scales surrounding the 

 solid base or 'disk of the stem, or attached to its apex. 

 "When the disk is large and surrounded by only a few 

 leaves, as in the crocus, it is called a corm. Bulbs 

 may be squamose or scaly, tunicated as in the onion, 

 fibrous, etc. 



The length of life of the stem and roots may be 

 only a single year, or annual; two years, or biennial; 

 or a number of years, or perennial. 



The trunk or woody stem of Exogens, or outside- 

 growers, shows on a transverse section a number of 



