STEM AXD BllANOIIES. 



11 



1 



■a 



by twining nhout some support ; prostrate, Ij'ing flat on the grouncl ; 

 trailing, runninpj alonf:^ over the surfaee of tlie <:jroiiii(l or other i)liiiits, etc. 

 Til us far we have studied the stem us it ordinarily appears to us al)ove 

 ground, but there are stems of vast importance which are wholly subter- 

 ranean and are commonly spoken of as roots. That of Solomon's-scal 

 (Fig. 15) will serve as an illustration of one form of such stems. Placed just 

 beneath the surface in a horizontal position, it "npears as a thickened, fleshy, 

 root-like body, bearing numerous I'ootlets, a terminal scaly bud at its 

 anterior extremity, and sending up a flower-stem, behind which are seal's 

 left by the falling awa^' of previous ones. Each year a new joint is added, 

 while commonly the oldest one rots away ; hence the stem is slowly, year by 

 year, creeping forward. Such au underground stem is called a rhizomei 



Fio. Ifi.— nviipinth l)nlb. 



FiO. 17. — Vorticnl scotion of a livarinth bulb. 



Rhizomes present many different forms. They are simple or In-anched, 

 horizontal or ascending, fleshy, etc., and are perennial. Podophyllum, 

 sanguiuarii, ami iris are among our active medicinal plants which have 

 stems of this chai'actei". 



In general, rhizomes contain the more active principles of the plants, 

 and in the greatest proportion. As such plants st<-re away a great amount 

 of nourishment in their fleshy stems for the succeeding year's needs, they 

 commonly make vigorous growth early In spring, and are mostly early 

 bloomers. 



Another common form of subteiTanean stem is the bulb ; that of thq 

 hyacinth (Fig. IG) affording a good illuatratiou. A vertical section (Fig. 17) 



