96 



LEAVES AND FOLIAGE 



l.i:>. I'ult.ite ka\eb ot ho-cilled 

 Egyptian lotus. 



Kentucky coffee tree. Remark- 

 able differences in forms are 

 seen by comparing seed-leaves 

 with mature leaves of any plant 

 (Fig. 143). 



202. THE LEAF AND 

 ITS ENVIRONMENT. — 

 The form and shape 

 of the leaf often have 

 direct relation to the 



place in which the leaf grows. Floating leaves 

 are usualli/ expanded and flat, and the petiole 

 varies in length with the depth of the water. 

 Submerged leaves are usually linear or thread- lil-e, 

 or are cut into very narrow divisions. Thereby is 

 more surface exposed, and possibly the leaves are 

 less injured by moving water. 



203. The largest leaves on a sun -loving plant 

 are usually those which are fulhj exposed to light. 

 Compare the sizes of the leaves on the ends of 

 branches with those at 



136. Linear- 

 acuminate 

 leaf of 



:> 



the base of the branches 



or in the interior of the , \ //c 



tree -top. In dense foli- f^ 



age masses, the petioles ^^- 



of the lowermost or ^^^ j 



undermost leaves tend to 

 ^'^^^' elongate — to push the 

 leaf to the light (Fig. 144). 



204. On the approach of win- ^^^^ 



ter the leaf ceases to work, and V 



often dies. It may drop, when it ^^t. Short-obiong leaves of box. 

 is said to be deciduous ; or it may remain on the plant, 

 when it is said to be persistent. If persistent leaves re- 

 main green during the winter, the plant is said to be 



