348 



A TEXTBOOK OF BOTANY [Ch. VII, 2 



Fig. 239. — Pod of a 

 Poppy ; X {. 



It stands at the sum- 

 mit of a long stiff stalk. 



wise usuallj' dehisce by disuniting the 

 joined edges, though sometimes they 

 spht also down the carpellary midribs. 

 Frequentl}-, however, the dehiscence 

 follows no morphological line in the 

 ovar}', 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 anj^ regard to morpho- 

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

 Mustard familj^ the carpels mostly split 

 away as valves from the placentee, which 

 persist for a time as a framework (Fig. 

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

 prevail throughout famihes in waj's 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 bj^ the 

 little AKENES of the Straw- 

 berr}^ and Buttercu]i, com- 

 monly supposed to be seeds Fig. 240. — Honesty. Lunaria annua. 



(Fig. 241). They are in fact "' "'"''l' *^ Persistent partitions of 

 " . ^ the pods lorm smnniK plates; X j. 



functionally seeds, l)0th in (From Bailey.) 



