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; 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. I'he 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 unwn, one. 

 &n([foliolum, leaflet. 



Bifoliolate, of two leaflets, from the Latin bis, twice, andfoliolum, 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. 



