370 



RELATION TO ENVIRONMENT. 



jects high enough to cHmb upon. In the prostrate type, there 

 is economy in stem building. The plants dcjjend on the ground 

 for support, and it is not necessary to build strong, woody trunks 

 for the display of the foliage which would lae necessary in the 

 case of an erect ])lant with a foliage area as great as some of the 



Prostrate t\'iie ril tluj watir U'rn {Uhirsilia). 



prostrate stems. This gain is offset, at least to a great extent, 

 by the loss in ability to display a great amount of foliage, which 

 can Ije done onh- on tlie upper side of the stem. 



Other advantages gained l)v the ]irostrale stems are protec- 

 tion from wind, from cold in tlie more rigonuis climates, and 

 some propagate themselves b\' taking root liere and there, as in 

 certain roses, the stra\v1)err\' jilanl, etc. Some plants have 

 erect stems, and thei"i send out runners lielow which lake root 

 and aid the jjlant in sjireading and niultipl\ing its niuiihers. 



720. The decumbent type.— In lliis type (lie stem is hrsl erect, 

 but later bends down in (he form of an arch, and strikes root 

 where the tip touches tlie gi-oimd. Some of the rasj)berries 

 and blackberries are of this l}pe. 



