THE FRUIT. 97 



calyx-limb dries and decays, but the receptacular tube persists and becomes fleshy. 

 In the ripe Mulberry (fig. 571), the female flowers of which form a dense spike, the four 

 sepals are succulent, and enclose the pistil; they may thus themselves be regarded 

 as belonging to the fruit. Involucres, which we have described in the paragraph 

 on bracts, usually persist around the fruit and grow with it ; such is the case with 

 the involucres of Composite, the cups of the Acorn (fig. 232), of the Nut (fig. 233), and 

 of the Chestnut (fig. 234). 



Dehiscence. Dehiscence is the act by which the ripe pericarp opens to let the 

 seeds escape. Fruits which thus burst spontaneously are called dehiscent (dehiscens : 

 Tulip, Iris, fig. 531) ; the term indehiscent (indehiscens) is applied to 1, fleshy fruits 

 which do not open, but decay, and thus free the seeds (Apple, figs. 448, 449 ; Peach, 

 fig. 519 ; Melon, Pumpkin] ; 2, dry fruits, whose pericarp is pierced by the embryo 

 in germination (Wheat, Buckwheat, Oat, fig. 526 ; Anemone, fig. 523). 



Valves (valvce, valvulce) are the pieces into which the pistil separates when ripe, 

 to allow the seeds to escape ; according to the number of these, the fruit is said to 

 be univalved, bivalved, &c. (univalvis, bivalvis, &c.) ; sometimes the separation is 

 incomplete, the valves only opening to a half or a quarter of their length, or at the 

 top only. Apocai'pous fruits dehisce by the ventral suture (Columbine, fig. 497 ; 

 Larkspur, fig. 512 ; Caltha, fig. 511), or by the dorsal nerve (Magnolia), or by both at 

 once (Pea, fig. 516, and other Leguminosce) ; in the latter case, there are two valves 

 to one carpel. 



The dehiscence of plurilocular syncarpous fruits is septicidal (d. septicida) when 

 the septa split into two parallel plates, and the united carpels separate (St. John's 

 Wort, fig. 527 ; Colchicum, fig. 529 ; Mullein, Scrophularia, fig. 528) ; each valve then 

 represents a carpel. The placentas may fall away with the valves, or form a solid 

 central column (Salicaria, fig. 530). In all cases, the edges of the valves are said 

 to be inflexed. The dehiscence of plurilocular syncarpous fruits is loculicidal (d. locu- 

 licida) when it takes place by the dorsal suture ; this results from the septa being 

 more firmly united than the median fibro-vascular bundles of the carpels; each 

 valve then represents the halves of two carpels, and the valves are described as sep- 

 tiferous in the middle (v. medio-septiferce). Sometimes the placentas are continued 

 along the septa (Lily, Iris, fig. 531), at others they remain consolidated into a 

 central column ; sometimes, again, the placentas may retain a portion or the whole 

 of each septum, and the central column then presents as many wings or plates as 

 there were septa in the ovary before its dehiscence (Rhododendron, Datura, fig. 532) ; 

 this variety of loculicidal dehiscence is called septifragal. 



The same fruit may be both septicidal and loculicidal ; thus, in Foxglove, which 

 is two-carpellary, the septa first separate, then the dorsal nerve of each carpel splits, 

 and each of the four resulting valves represents half a carpel. 



Syncarpous fruits with parietal placentas usually dehisce by placental sutures, 

 when each valve represents a carpel, and has placentiferous margins (val. marginibus 

 placentiferce, Gentian, fig. 533), or by the dorsal sutures, when each valve represenls 

 the halves of two contiguous carpels, and is placentiferous in the middle (v. medio- 

 placentiferce, Heartsease, fig. 534; Willow, fig. 535), or by the separation of the valves, 



H 



