114 



STRUCTURAL BOTANY. 



t97, 98. 



291. Again: if the lowest pair of veinlets are length- 

 ened and more or less recurved, the leaf will be vari- 



4 6 5 7 11 10 9 8 



320-330, Diagrams of pinnate-veined leaf-forms. 



ously modified in respect to its base, becom- 

 ing (334) cordate, or heart-shaped, an ovate 

 outline with a sinus or re-entering angle at 

 base; (331) auriculate, with ear-shaped lobes 

 at base; (337) sagittate, arrow-shaped, with the lobes 

 pointed, and directed backward; (332) hastate, halbert- 

 shaped, the lobes directed outward. 



336 



Forms of leaves. 330, Silene Virginica. 331, Magnolia Fraseri. 336, Arabis dentata. 337, Polygonum 

 sagittatum. 332, Hepatica acutiloba. 333, Asarum Virginicum. 334, Hydrocotyle Americana. 335, H. 

 umbellata. 



292. Pinnatifid forms. The following pinnate- 

 veined forms, approaching the compound leaf, depend 

 less upon the proportion of the veinlets than upon the 



