58 



LEAVES. 



[SECTION 7. 



feather-veined (i. e. pinnatety '-veined) simple leaf; as will be seen at once 

 on comparing the forms. The leaflets of the former answer to the lobes or 

 divisions of the latter ; and the continuation of the petiole, along which the 

 leaflets are arranged, answers to the midrib of the simple leaf. 



150. Three sorts of pinnate leaves are here given. Fig. 156 is pinnate 

 with an odd or end leaflet, as in the Common Locust and the Ash. Fig. 

 157 is pinnate with a tendril at the end, in place of the odd leaflet, as in 

 the Vetches and the Pea. Fig. 158 is evenly or abruptly pinnate, as in the 

 Honey-Locust. 



151. Palmate (also named Digitate) leaves are those in which the leaf- 

 lets are all borne on the tip of the leaf- 

 stalk, as in the Lupine, the Common 

 Clover, the Virginia Creeper (Fig. 93), 

 and the Horse-chestnut and Buckeye 

 (Fig. 159). They evidently answer to 

 the radiate-veined or palmately -veined 

 simple leaf. That is, the Clover-leaf of 

 three leaflets is the same as a palmately 

 three-ribbed leaf cut into three separate 

 leaflets. And such a simple five-lobed 

 leaf as that of the Sugar-Maple, if 

 more cut, so as to separate the parts, 



would produce a palmate leaf of five leaflets, like that of the Horse-chestnut 

 or Buckeye. 



152. Either sort of compound leaf may have any number of leaflets ; yet 

 palmate leaves cannot well have a great many, since they are all crowded 

 together on the end of the main leaf-stalk. Some Lupines have nine or 

 eleven ; the Horse-chestnut has seven, the Sweet Buckeye more commonly 

 five, the Clover three. A pinnate leaf often has only seven or five leaflets, 

 or only three, as in Beans of the genus Phaseolus, etc. ; in some rarer cases 

 only t"o; in the Orange and Lemon and also in the common Barberry 

 there is only one ! The joint at the place where the leaflet is united with 

 the petiole distinguishes this last case from a simple leaf. In other species 

 of these genera the lateral leaflets also are present. 



153. The leaflets of a compound leaf may be either entire (as in Fig. 

 12G-128), or serrate, or lobed, cleft, parted, etc. ; in fact, may present all 

 the variations of simple leaves, and the same terms equally apply to them. 



154. When the division is carried so far as to separate what would be 

 one leaflet into two, three, or several, the leaf becomes doubly or twice 

 compound, either ^innately or palmately, as the case may be. For example, 

 while the clustered leaves of the Honey-Locust are simply pinnate, that is, 

 once pinnate, those on new shoots are bipinnate, or twice pinnate, as in 

 Fig. 160. When these leaflets are again divided in the same way, the leaf 



Fia. 159. Palmate (or digitate) leaf of five leaflets, of the Sweet Buckeye. 



