132 THE FRUIT. [LESSON 20. 



358. Dehiscence of a pod resulting from a compound pistil, when 

 regular, takes place in one of two principal ways, which, are best 



shown in pods of two or three cells. Either the pod 

 splits open down the middle of the back of each 4ceH? 

 when the dehiscence is loculicidal, as in Fig. 305 ; or 

 it splits through the partitions, after which each cell 

 generally opens at its inner angle, when it 

 is septicidal, as in Fig. 306. These names 

 are of Latin derivation, the first meaning 

 " cutting into the cells " ; the second, " cut- 

 ting through the partitions." Of the first 

 sort, the Lily and Iris ( Fig. 305) are good 

 examples ; of the second, the Rhododen- 

 dron, Azalea, and St. John's-wort. From 

 the structure of the pistil (305-311) the 

 student will readily see, that the line down 

 the back of each cell answers to the dorsal suture of the carpel ; so 

 that the pod opens by this when loculicidal, while it separates into 

 its component carpels, which open as follicles, when septicidal. 

 Some pods open both ways, and so split into twice as many valves 

 as the carpels of which they are formed. 



359. In loculicidal dehiscence the valves naturally bear the par- 

 titions on their middle ; in the septicidal, half the thickness of a 

 partition is borne on the margin of each valve. See the diagrams, 

 Fig. 307-309. A variation of either mode sometimes occurs, as 



shown in the diagram, Fig. 309, where the valves break away from 

 the partitions. This is called septifragal dehiscence ; and may be 

 seen in the Morning-Glory. 



360. Three remaining sorts of pods are distinguished by proper 

 names, viz. : 



FIG. 305. Capsule of Iris (with loculiciilal dehiscence), below cut across. 



FIG. 306. Pod of a Marsh St. Jolm's-wort, with septicidal dehiscence. 



FIG. 307. Diagram of septicidal ; 308, of loculicidal ; and 308, of septiftagal dehisconc*. 



