24 



BOTANY 



PART I 



ROOT-STOCKS or RHIZOMES. By means of such subterranean shoots 

 many herbaceous perennial plants are enabled to persist through the 

 winter. A rhizome develops only reduced leaves in the form of 

 larger or smaller, sometimes scarcely visible, scales. By the presence 

 of such scale leaves, with their axillary buds, and by the absence of 

 a root-cap, as well as by its internal structure, a rhizome may be dis- 

 tinguished from a root. Rhizomes usually produce numerous roots ; 

 but in a few cases these are wanting and the rhizome itself functions 

 as a root. Rhizomes often attain a considerable thickness and store 



Fio. 24. Rhizome of Coralllorrhiza in- 

 nata. a, Floral shoot ; 6, rudiments 

 of new rhizome branches. (After 

 SHACHT, nat. size.) 



zk 



FIG. 25. Longitudinal section of Tulip 

 bulb, Ttdipa Gesnerwna. zk, Muililioi 

 stem ;i zs, scale leaves ; v, terminal 

 bud ; k, rudimentof a younj; bulb ; , 

 roots. (Nat. si/c.) 



up nutritive material for the formation of aerial shoots. In the 

 illustration on the preceding page (Fig. 23) is shown the root-stock of 

 Solomon's Seal (Polygonatum multiflorum). At d and c are seen the 

 scars of the aerial shoots of the two preceding years ; and at b may 

 be seen the base of the stem growing at the time the rhizome was 

 taken from the ground, while at a is shown the bud of the next 

 year's aerial growth. The rhizome of Coralliorrhiza innata, a sapro- 

 phytic Orchid, which grows in soil rich in humus, affords a good 

 example of a root-stock functioning as a root (Fig. 24). BULBS, also, 

 belong to the class of metamorphosed shoots. They represent a 

 shortened shoot with a flattened, discoid stem (Fig. 25 zk), the fleshy 



