82 



A TEXTBOOK OF BOTANY [Ch. Ill, 10 



a kind of branching 

 of the face of the 

 leaf. Such seems the 

 case in the lid of the 

 Nepenthes pitcher 

 earlier mentioned, 

 and in the corona, 

 or crown, of the 

 petals of some 

 flowers, notably the 

 Daffodil (Fig. 230). 

 Thus we see that 

 the leaf, though 

 having a definite 

 and typical primary 

 function and struc- 

 ture, is yet highly 

 plastic in all of its 

 features, and can be 

 led along many dif- 

 ferent lines of de- 

 velopment. Such 



Fig. 57. — Special forms of stipules ; X |. morphological plas- 

 Euphorbia, paired spines : Galium, with two ticitv is character- 

 opposite leaves simulating a 6-leaved whorl : , . ' .. . 

 Tulip Tree, bud scales : Polygonum, united in a IStiC 01 all parts 01 

 sheath (ochrea) around the stem : Violet, acces- living beings and is 

 sory foliage. ' . ' 



one oi their distinc- 

 tive properties (page 39). The tracing of such lines of 

 development is the distinctive province of morphology. 



10. The Nutrition of Plants Which Lack 

 Chlorophyll 



While most plants possess chlorophyll and make their 

 own food, there are some which do not. If, now, all plant 

 food is based on grape sugar made in green tissues, how 

 do these chlorophyll-less kinds secure their supply? The 



