112 



PERICARP. 



then either dry, as the pea-pod, or succulent, as the currant- Dry peri- 

 carps are membranous, or coriaceous (leathery), or woody. Succulent 

 pericarps may be either wholly so, as the grape, or partly so, as the 

 peach and other stone fruit. 



548. Pericarp closed or open. With very few exceptions the 

 pericarp encloses the seed while maturing. In mignonette (322), 

 however^ it opens, exposing the seed, immediately after flowering. The 

 membranous pericarp of cohosh (Leontice) falls away early leaving the 

 seed to ripen naked. In yew (Taxus) the seed is never enclosed wholly 

 by its fleshy pericarp ; but in most of the other Coniferse, the close- 

 pressed, carpellary scales cover the seeds. One-seeded fruits, like thoSe 

 of butter-cups, etc., are liable to be mistaken for naked seeds. 



549. Dehiscence. The fleshy pericarp is always indehiscent. Its 

 seeds are liberated only by its decay, or bursting in germination. So 

 also itt many cases the dry pericarp, as the acorn. But more commonly 

 the dry fruit, when arrived at maturity, opens in some way, discharging 

 its seeds. Such fruits are dehiscent. 



550. Modes. Dehiscence is either valvular, porous, or circumscis- 

 sile ; valvular, when the pericarp opens vertically along the sutures, 

 forming regular parts called valves. These valves may separate quite 

 to the base, or only at the top, forming teeth, as in chickweed.. We 

 notice four modes of valvular dehiscence, viz. : 



1, Sutural, when it takes place at the sutures of any 1-celled peri- 

 carp, as columbine, pea, violet. 



429 430 481 



Dehiscence ; 429, sopticldnl ; 430, looullcidal ; 431, septifragal. 



2, Septicidal' (septum, partition, ccsdo, to cut), when it takes place 

 through the dissepiments (which are double, § 525). The carpels thus 

 separated may open severally by sutures, (Mallows), or remain inde- 

 hiscent, as in Vervain. 



3, Loculicidal {loculus, a cell, ccedo, to cut), when each carpel opens 

 at its dorsal suture directly into the cell (evening-primrose, lily). Here 

 the dissepiments come away attached to the middle of the valves. 



4, S^eptifragal {septum, and frango, to break), when the valves 

 separate from the dissepiments which remain still united in the axis 

 (Convolvulus). 



