INDEHISCENT FRUITS. 



429 



may be distinguished into Indehiscent fruits, Schizocarps, and dry Dehiscent fruits. 

 The indehiscent fruit never opens spontaneously. When ripe it comes away with 

 the inclosed seed and is concerned in the dispersal and establishment of this seed. 

 The indehiscent fruit is termed a Nut when it arises from a pistil constituted 

 of more than one carpel, as in the Lime (Tilia, figs. 321 2 and 321 3 ), an Achene when 

 produced from a monocarpellary pistil. When the contained seed is entirely fused 

 with the lining of the fruit-wall, as in Grasses (cf. vol. i. p. 599, fig. 141 3 ), the fruit 



Fig. 324. Flowering branch of Banksia serrata with thick-walled dehiscent capsules. (After Baillon.) 



is termed a Caryopsis. Sometimes the wall of the nut consists of an outer more 

 fleshy layer, and an inner harder layer after the manner of a drupe. Such a fruit, 

 as in the Fumitory (Fumaria, figs. 322 * and 322 2 ), is known as a drupaceous nut. 

 As a rule the nut is uni-loculate and contains but a single seed; and this notwith- 

 standing the terms of our definition, according to which a nut is the product of a 

 multi-carpellary ovary. Actually in development all the chambers but one (which 

 contains the ripe seed) atrophy. Only rarely are nuts multilocular, as in the Water- 

 star (Callitriche, figs. 322 3 and 322 4 ) which has a 4-chambered nut and forms a 

 transition to the schizocarp. 



The Schizocarp may be regarded as consisting of a number of Achenes unit- 

 together. Two or more carpels, each containing a seed, remain joined together during 



