ly-i- 



I'LAXT STIDIES 



leaves are in a tixed position, tliere are certain ones whose 

 leaves are able to perform movements according to the need. 

 Mention has been made already of such forms as Oxalis 

 (see Sl-t). ^vhosc leaves change their position readilj' in 

 reference to light. Motile leaves have been developed most 

 e.xtensively among the Legumiuos(B, the family to which 



;. in. 'rwo twi^iK of ;i Beneitivr jilant. 'T\i'- one to tlic luft shows the numerous 

 suiuU leaflets in llieir expanded position ; the one to the right shows the greatly 

 redticed surface, the leaflets foldetl together, the main leaf branches having 

 approached one another, and the main leaf-stalk having bent sharply downwards. 

 — After STKAsniiUiKii. 



belong peas, etc lu this ftiiiiily are the so-called "sen- 

 sitive phmts," wliii'li luive rciu'ived their popular name 

 from their sensitive response to light as well as td other 

 influences (sec l*'ig. 171). The acticiti and miinosa. forms 

 are the most notaljlc s('nsiti\"(! plants, and arc cspeciallv 

 dcvelopcil in arid regions. TIm^ leaves ai'e iisiiallv verv 

 large, but are so much lira.iichc(l tha.t each Ictif is c(un- 

 posed of very numerous snjtdl leaflets. Each lealiet has 



