42 



MANUAL OF BOTANY 



its place, which also, by developing laterally, likewise con- 

 tinues near the surface of the ground, or burrows beneath it. 

 From these peculiarities in the direction and growth of stems 

 and branches, we have a number of modifications needing 

 description. These are best treated of under two heads, nanaely, 

 those which are aerial, and those which are suhterranean. "We 

 can, however, by no means draw a distinct line between the 

 modifications of stem \^7hich these two divisions respectively 

 contain, as certain forms occasionally pass from one into the 

 other, thus being subterranean and aerial at different points, or 

 at different periods of their course. 



Fi«. 60. 



Fig. 61. 



Fi(i. 60. Contorted rhizome of Bistort {Polygonum Bistorla). Fig, 61, 



PrEemorse rhizome of the Devil's-bit Scabious (Scabiosa succisa), 



1. Aerial MoDiricATioNs or the Stem and Branches. — Of 

 these the more important are the runner, the offsei, the stolon, 

 the sucker, some forms of the rhinome, the phylloolade, and the 

 thorn. Certain forms of tendril may be included here. The 

 flower is also a modified shoot. The rhizome is usually sub- 

 terranean. 



■a,. The Runner or Flagellum {fig. 53). — This is an elon- 

 gated, slender, prostrate branch, ci, sent off from the base of the 

 stem, and giving off at its extremity leaves, r, and roots, /, and 

 thus producing a new plant, which extends itself in a similar 

 manner. This is well seen in the common Strawberry. 



b. The Offset {fig. 54). — This is a short, prostrate, more or 

 less thickened branch, which produces at its apex small roots 



