348 



A TEXTBOOK OF BOTANY [Cn. VII, 2 



/ 



FIG. 239. Pod of a 

 Poppy ; x 1. 



wise usually dehisce by disuniting the 

 joined edges, though sometimes they 

 split also down the carpellary midribs. 

 Frequently, however, the dehiscence 

 follows no morphological line in the 

 ovary, but occurs in new and independ- 

 ent positions connected with a par- 

 ticular method of dissemination. Thus, 

 in the capsules of Poppies new openings 

 arise around the tops of the fruits and 

 in Purslane the capsule splits right 

 across without any regard to morpho- 

 logical lines (Fig. 239) ; in some of the 

 Mustard family the carpels mostly split 

 away as valves from the placenta, which 

 persist for a time as a framework (Fig. 

 240) ; and other arrangements also occur, some of which 

 prevail throughout families in ways to show that large 

 structural and hereditary factors enter along with adapta- 

 tion into the construction of fruits. On the basis of their 

 aggregate structural fea- 

 tures, the dry fruits are 

 classified and named as FOL- 



LICLES, LEGUMES, SILICLES, 

 etc., these distinctions hav- 

 ing importance in connection 

 with the taxonomy of plants. 

 The only dry fruits which 

 do not dehisce at all are 

 those which contain but a 

 single seed, as typified by the 

 little AKENES of the Straw- 



>erry and Buttercup, com- 

 monly Supposed to be Seeds FIG. 240. Honesty rLunariaannua, 

 CFiff 241") Thpvflrpin faot in which the persistent partitions of 



tiey are in tact the pcds form shining plates . x ^ 



functionally seeds, both in (From Bailey.) 



