66 



MORPHOLOGY OF LEAVES AS FOLIAGE. [LESSON 9. 



Some Lupines have nine or eleven ; the Horsechestnut has seven, 

 the Sweet Buckeye more commonly five, the Clover three. A pin- 

 nate leaf often has only seven or five leaflets, as in the Wild Bean 

 or Groundnut j and in the Common Bean it has only three ; in 



some rarer cases only two ; in 

 the Orange and Lemon only 

 one! The joint at the place 

 where the leaflet is united with 

 the petiole alone distinguishes 

 this last case from a simple 

 leaf.* 



170. The leaflets of a com- 

 pound leaf may be either entire 

 (as in Fig. 126-128), or ser- 

 rate, or lobed, cleft, parted, 

 &c. : in fact, they may pre- 

 sent all the variations of simple 

 leaves, and the same terms 

 equally apply to them. 



171. When this division is 

 ^ carried so far as to separate 



what would be one leaflet into 

 two, three, or several, the leaf 

 becomes doubly or twice com- 

 pound, either pinnately orpal- 

 mately, as the case may be. 

 For example, while some of the leaves of the Honey-Locust are 

 simply pinnate, that is, once pinnate, as in Fig. 128, the greater part 





* When the botanist, in describing leaves, wishes to express the number of 

 leaflets, he may use terms like these : 



Unifoliolate, for a compound leaf of a single leaflet ; from the Latin unum, one, 

 andfoliolum, leaflet. 



Bifoliolate, of two leaflets, from the Latin bis, twice, anftfoliolum, leaflet. 



Trifoliolate (or ternate), of three leaflets, as the Clover ; and so on. 



When he would express in one phrase both the number of leaflets and the way 

 the leaf is compound, he writes : 



Palmately bifoliolate, trifoliolate, plurifoliolate (of several leaflets), &c., or else 



Pinnately bi-, tri-, quadri-, or pluri-foliolate (that is, of two, three, four, five, or 

 several leaflets), as the case may be. 



FIG. 130. A twice-pinnate (abruptly) leaf of the Honey -Locust. 



