ADHESION 



51 



be continued into a terminal ])oint. They may be concave, as in Thco- 

 hroma (Fig. 71); the margin may be toothed and the a})ex tootlied or 

 fim])riated, as in Siletic (Fig. 72); the toothing of the margin may extend 

 into a ])imiatifid condition, as in the calyx 

 lobe of Rosa canina (Fig. 73), and that of 

 a toothed or fimbriate apex into the cleft 

 or divided state of chorisis. 



The Pappus. — The peculiarly di\ided 

 calyx illustrated in Fig. 79, a, is denomi- 

 nated a rai)pus, and this term has been 

 extended to all forms of the calyx (Figs. 

 74 to S3) existing in that family (the 

 Com positae) and in some others. Fig. 80 

 illustrates the action of median, as well as 

 of lateral chorisis, in the development of 

 a double pappus, the outer circle being 

 much shorter and different in kind. 



The se^•eral forms of perigone i)arts 

 corresj)onding to those of leaves (see leaf-forms) and numerous inter- 

 mediate ones not illustrated, should be carefully considered by the 

 student, as they ha^e a most important bearing ui)on the forms of the 

 corolla produced by cohesion, which we shall shortly consider. 



FiK. 71. ConoMVc petiil of Tlicohronut. 

 72. FlowtT of .SiVi/K, the i)etals loothod 

 at apex and bearing a crown at junction 

 of limb with claw; also a conspicuous 

 anthophore in base of calyx. 73. Pinna- 

 tifid sepal of Jiusa. 



IS. 76. n. 



Figures illustrating forms of the pappus; Fig. 71. Pappus little changed from ordinary superior 

 calyx-limb. 75. That of Tanareium, reduced to a short cup. 70. That of Absinlhiuiri, practically 

 obsolete. 77. That of yVycthia, 2 of the calyx-teeth awned. 78. That of Griiidelia, the two remaining 

 calyx-teeth aristiform. 79. That of Aruica, the ordinary setose form. SO. The double pappus of 

 £ri(/(To;i, the outer series very short. 81. Plumose bristle from pappus of Lasiopoffon. 82. Scaly bristle 

 from pappus of Eriosphaern. H',i. Serrate bristle from pappus of Cineraria. 



Adhesion. — Both adhesion and cohesion are exceedingly common in 

 the case of the })erigoiic. The foiiner has already been pretty fully 

 considered. \Vry rarely is it so coiniilete that there is not at least a 

 ])()rtioii of the parts remaining free. Since the adherent ])arts are 



