THE PERIGONE. 



21 



Flc. 5S . 



n^.i>i. 



FLcr. t^. 



F,g. fa's 



FlCP . oJ 



Flg.(?^. 



Fcoi.to 



suffix "phyllous"— thus, Moiiopbyllous, 

 Diphyllons, Tripbylloiis, and so on. 



The parts of the calyx commonly pre- 

 sent themselves to us in the form of a cir- 



cle, though sometimes as two (Mustard). 



The strictly typical state calls for a gen- 

 eral resemblance between the form of the 

 perigone parts and tbat of tbe foliage 

 leaves of the plant which bears them. 

 They sometimes display a keel correspond- 

 ing to tbe mid-rib of the leaf, and, as in 

 the leaf, this may be continued into a ter- 

 minal point. 



They may be concave, as in Tbeobroma 

 (Fig 93); the margin may be toothed and 

 the apex toothed or fimbriated, as in 

 Silene (Fig. 18). The toothing of the 

 margin may extend into a pinnatifid con- 

 dition, as in the calyx lobe of Rosa canina 

 (Fig. 60), and that of a toothed or fimbri- 

 ate apex into the cleft or divided state of 

 chorisis. The peculiarly divided calyx 

 illustrated in Fig. 64 is denominated a 

 Pappus, and this term has been extended 

 to all forms of the calyx (61 to 68) ex- 

 isting in that family (the Compositae) 

 and in some others- Fig. 68 illustrates 

 the action of median, as well as of lateral, 

 chorisis, in the development oi a double 

 pappus. The several forms of perigone 

 parts corresponding to those of leaves 

 (see leaf-forms) and numerous interme- 

 diate ones not illustrated, shijiikl be care- 

 fully considered by the student, as they 

 have a most important bearing upon 

 the forms of the corolla produced by co- 

 hesion, which we shall shortly consider. 



Both adhesion and cohesion are ex- 

 ceedingly common in the case of the peri- 

 gone. The former has already been pretty 

 fully considered. Very rarely is it so 

 complete that there is not at least a por- 



