304 ORGANOGRAPHY. 



Fig. 648. Fig. 649. 



Fig. 650. 



Fig. 648. Fruit of Lychnis 



Fig. 649. TTuit of Dianthua 



Fig. 650. Fruit of . Mignonette 

 {^Reseda). 



and many other Caiyophyllaceoiis Plants, the dehiscence only 

 takes place at the upper part of the fruit, which then appears 

 toothed, the number of teeth corresponding to that of the 

 valves. A somewhat similar mode of partial dehiscence occurs 

 in certain Saxifrages, and in the Mignonette {fig. 650), &c. ; in 

 the latter plant one large orifice may be observed at the summit 

 of the fruit at an early stage of its growth, and long before the 

 seeds are ripe. All these modes of partial dehiscence are by 

 some botanists placed under the head of porous dehiscence, but 

 from which, in most cases at least, they are readily distin- 

 guishable. At other times, the separation of the fruit into 

 valves is more or less complete, so that the nature of the de- 

 hiscence is at once evident. We now pass to consider the 

 various modifications of such forms of valvular dehiscence. 



In fruits which are formed of but one carpel, the dehiscence 

 may take place by the ventral suture only, as in the Hellebore, 

 Columbine {fig. 651), and Pgeony {fig. 683); or by the dorsal 

 suture only, as in some Magnolias {fig. 652); or by both dorsal 

 and ventral sutures, as in the Pea {fig. 653), Bean, and many 

 other Leguminous Plants. This form of dehiscence is com- 

 monly known as sutural. 



In compound fruits having two or more cells with axile pla- 

 centation, there are three leading forms of dehiscence, which 

 are called respectively, septicidal, loculicidal, and septifragal. 



A. Septicidal Dehiscence. — In this form, the fruit is sepa- 

 rated into its component carpels by a division taking place 

 between the two halves of each dissepiment {fig. 654). It is 

 seen in the Colchicum, in the Scrophularia, and the Rhododen- 

 dron, &c. In this dehiscence each valve corresponds to a 

 carpel, and the valves arc said to have their margins turned 

 inwards. In tliis form of dehiscence, the placentas with the 

 seeds attached, arc either carried away with the valves {fig. 

 655), as in the Colchicum, Sec. {fig. 654) ; or the valves break 



