98 



STRUCTURAL BOTANY. 



vening tissue. 



The prefix pinnated is obviously used in contrast 

 with palmated among palmate-veined forms. 



293. Pinnatifid (pinna, feather, findo, to cleave), feather-cleft, 

 the tissue somewhat sharply cleft between the veinlets about 

 half-way to the midvein, forming oblong segments. When the 

 segments of a pinnatifid leaf are pointed and curved backward, 

 it becomes runcinate, i. e., re-uncinate. When the terminal seg- 

 ment of a pinnatifid leaf is orbicular in figure and larger than 

 any other, presenting the form of the ancient lyre, the form is 

 termed lyrate. 



342 



341 



Feather-veined leaves, approaching the compound. 338, Quercus imbricaria undulate. 339, Q. alb* 

 (White Oak) lobate-sinuate. 340, Q. macrocarpa lyrate. 341, Mulgedium (Milkweed). 342, Bipin- 

 natifld lenf of Ambrosia artemisifolia (Ilogweed). 



294. Pinnately parted implies that the incisions are deeper 

 than pinnatifid, nearly reaching the midvein. In either case the 

 leaf is said to be sinuate when the incisions (sinuses) as well as 

 the segments are rounded and flowing in outline. Such segments 

 are lobes, and the leaves lobate or lobed, a very generic term. 



295. Palmate forms. The palmate venation presents us 

 with a set of forms which are, in general, broader in proportion 

 than the pinnate, having the breadth about equal to the length. 

 Such a leaf may be rarely broadly ovate, or broadly cordate, 

 terms which require no further explanation. Or it may be 

 JReniform, kidney-shaped, having a flowing outline broader than 

 long, concave at base ; or Peltate, shield-form, the petiole not 

 inserted at the margin, but in the midst of the lower surface of 

 the blade. This singular form evidently results from the blend- 



