152 



PRACTICAL COURSE IN BOTANY 



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K 



bane and bitterweed {Helenium 

 ienuijolium) , illustrate this relation. 



On the other hand, when the leaves 

 are large and rounded in outline, as 

 those of the sunflower, hollyhock, and 

 catalpa, they are usually separated 

 by longer internodes, or their blades 

 are cut and incised so that the sun- 

 light easily strikes through to the 

 low^er ones. 



170. Other external characteristics 

 to be observed in leaves are : — 



(1) General Outline : whether round, oval, heart-shaped, 

 etc. (Figs. 191-197). 



(2) Margins: whether unbroken {entire), or variously 

 toothed and indented. (Figs. 198-202.) 





Fig. 190. — Narrow leaves 

 in crowded vertical rows. 



Figs. 191-197. — Shapes of leaves : 191, lanceolate ; 192, spatulate; 193, o-val; 

 194,obovate; 195, kidney-shaped ; 196, deltoid; 197,lyrate. (191-195 a/<erGiwY.) 



(3) Texture: whether thick, thin, soft, hard, fleshy, 

 leathery, brittle. 



(4) Surface: smooth, shining, dull, wrinkled, hairy, or 

 otherwise roughened. 



