THEIR STRUCTURE AND FORMS. 



101 



prolongation, the RHACHIS, which answers to the midrib of a pin- 

 nately veined simple leaf. There are three principal sorts, and 

 some subordinate ones. That is, a pinnate leaf may be 



Impari-pinnate, or pinnate with an odd leaflet, i. e. a terminal 

 one, as in Fig. 203 ; and this is the commoner case. 



Cirrhiferous Pinnate, or pinnate with a tendril (Fig. 204), as 

 in the proper Pea tribe and Bignonia. Here either the termi- 

 nal leaflet only, or the upper lateral leaflets also, are replaced 

 by tendrils. 



Pan-pinnate, or Abruptly Pinnate, destitute of a terminal leaflet 

 or of any thing answering to it, as in Fig. 205. 



Interruptedly Pinnate denotes merely a striking inequality of 

 size among the leaflets : Lyrately Pinnate, one in which the termi- 

 nal leaflet is largest and the lower small. 



196. Palmate or Digitate Leaves (Fig. 206, 93) are those in 

 which the leaflets all stand on the 

 summit of the petiole. Digitate 

 (fingered) was the old name, when 

 the term palmate was restricted to 

 a simple but palmately lobed leaf 

 of this type. But since the time 

 of DeCandolle the two names have 

 been used interchangeably. Pal- 

 mate leaves have no primary dis- 

 tinction into sorts, except as to 

 the number of leaflets. These can 

 never be very numerous ; but there are full}' a dozen in some 



FIG. 203. A7i impari-pinnate or odd pinnate leaf. 204. Pinnate with a tendril 

 205. Abruptly pinnate leaf of a Cassia. 



FIG. 206. Palmately or digitately 5-foliolate leaf of a Buckeye, YEsculus. 



