u 



PLAKT STUDIES 



ally arranged in a delinite nnmber of vertical rows. It is 

 to the advantage of tlie plant for tliese leaves to sliade one 

 another as little as p(jssible. Therefore^ the narrower the 

 leaves, the more nuniei'ous may be the vortical rows (see 



Figs. 7. s) : and 

 ^ the broader the 

 leaves tlie fewer 

 tlie verti(-al rows 

 (see Fig. 1). A 

 relation exists, 

 t h e r e f o re. b e - 

 tween thcl)readth 

 of leaves and the 

 nnndjer of verti- 

 cal rows, and the 

 meaning of this 

 becomes plain 

 when the light-re- 

 lation is consid- 

 ered. 



IS. Relation of 

 length to the dis- 

 tance between 

 leaves of the same 

 row. — Tlic leaves 

 in a. vci'tical row 

 may Ije close togtfhcr or far ajiart. If they should lie close 

 together a.nd at the same time hmg. it is evident that they 

 will shade each other consideraldy, as tlie light cannot well 

 strike in between them and reacli tlic snrface of the lower 

 leaf. Therefore, flu; (closer together the Icavi's of a verti- 

 cal row, the shorter are the leaves ; and tlic farllicr apart 

 the leaves of a row. ilie longer iiiav thev be. ShdiM leaves 

 permit the light to strike between thcni even if llicv arc 

 close together on the stem ; and long leaves permit the 

 same thing only when tliey are fa.r apart on the stem. A 



Fig. 7. An Ea.ster lily, showing narrow Icavc's and 

 numerous vertical rows. 



