222 



FOUNDATIONS OF BOTANY 



FIG. 166. Akenes of a Buttercup. 



A, head of akenes ; B, section of a single 



akene (magnified) ; a, seed. 



that is, they remain closed after ripening. Dehiscent 

 fruits when ripe open in order to discharge their seeds. 



The three classes which im- 

 mediately follow Sect. 237 

 belong to this division. 



235. The Akene. The 

 one-celled and one-seeded 

 pistils of the buttercup, 

 strawberry, and many other 

 flowers, ripen into a little 

 fruit called an akene (Fig. 

 166). Such fruits, from 

 their small size, their dry 

 consistency, and the fact that they never open, are usually 

 taken for seeds by those who are not botanists. 



In the group of plants to which the daisy, the sunflower, 

 and the dandelion belong, the akenes consist of the ovary 

 and the adherent calyx tube. The limb of the calyx is 

 borne on the summit of many akenes, sometimes in the form 

 of teeth, sometimes as a tuft 

 of hairs or bristles (Fig. 267). ^ 



236. The Grain. Grains, 

 such as corn, wheat, oats, bar- 

 ley, rice, and so on, have the 

 interior of the ovary com- 

 pletely filled by the seed, and 

 the seed-coats and the wall of 

 the ovary are firmly united, as 

 shown in Fig. 6. 



237. The Nut. A nut (Fig. 167) is larger than an 

 akene, usually has a harder shell, and commonly contains 



FIG. 167. Chestnuts. 



