ITS 



I'LANT STUDIES 



whole plant body is exposed to the wider sttpplv, and there- 

 fore absorption may take place tlirough the whole surface 

 rather than at any pa.rticular region sucli a„s tlie root. In 

 order that this may lie done, however, it is necessary for 

 tlie epidermis tn have thin walls, wliicli is nstially not tlie 

 case in epidermis exposed 

 to the air. whcr<' a. certain 

 amount of }iriitecf ion is 

 needed in the way <if 

 thickening. 



(2) Roots vuich reduced 

 or loantiiKj. — It must l)e 

 evident that if water is 

 being aiis(U'bcd bv the 

 whole free sui'face of tlie 

 ]ilant, there is net so 

 much need fi>i' a special 

 root region fur absorp- 

 tion. Therefore, in such 

 water plants tlie rout sys- 

 tem may be mucli re- 

 duced, or may even disaji- 

 ])ear entirely. It is often 

 I'ctaincd, howcvci', to act 

 as a lioldfa.st, I'atlier tlian 

 as an a))Sorl)cnt Di'gan. fcr 

 most water plants ancdioi' 

 themselves to seme sup- 

 jiort. 



(o) Reduction of teuter-coitdurf iiKj fisxHea. — In tlie (U'di- 

 nary soil-related plants, not only is an aliserliing rout sys- 

 tem necessai'y, liiit. also a conducting system, to carry tlie 

 water absorjjed from I In; roots to tlie lea^'cs and elsewhere. 



It has already 1 n noted that this conducting system takes 



the form of woody stra.nds. It is evident that if water 

 is being absorlied by the whole surface of the plau^ the 



Fic. ITill. t'i-;iL2:iiiriit of a comnmu ftcnxvecd 

 iFiiriix], slMiwilii: tlu- h.iily uilh I'drkins.'- 

 lirini.-lih;- ;iii,l bhia.liT-liki' air rai itir>. - 

 Aftrr Lri;i;s-i:N. 



