sect, ii PHAKEROGAMIA 459 



The Fruit 



The fruit of Angiosperms has a more varied and complicated 

 structure than in the case of Gymnosperms, whose flowers suffer but 

 slight modification in formation of the fruit. 



The fruit possesses a different structure according as it is derived 

 from an apocarpous or a syncarpous gyncecium. In the first case the 

 ripe carpels are separate and are termed FRUITS ; in the second the 

 carpels continue united, at least until the maturity of the fruit. A fruit 

 of a more complicated structure occurs when other members of the 

 flower than the gyncecium take part in its formation. Aggregated 

 fruits of this nature have been already described (p. 433). 



That part of the fruit enveloping the seeds, consisting sometimes of 

 the carpels alone, sometimes of the carpels and the adherent receptacle, 

 is termed the pericarp or fruit-wall. The pericarp frequently 

 appears to be differentiated into zone-like layers of tissue. The 

 outer layer is then termed the exocarp, the innermost the ENDOCARP, 

 and the layer sometimes lying between them the MESOCARP. 



According to the character of the pericarp and its condition at 

 maturity, several varieties of fruit have been distinguished, of which 

 the following are the most important. 



I. The Capsule. — Fruit with a dry pericarp, dehiscing at maturity. 

 Most frequently the carpels separate 

 from one another by longitudinal 

 slits (septicidal dehiscence), or 

 each carpel is split in half longi- 

 tudinally (loculicidal dehiscence, 

 Fig. 391). In more rare cases the 

 seeds escape through pores (pori- ■"■ 



CIDAL DEHISCENCE, e.g. PapaVCr). Fio- 394.— Diagrammatic sections of capsules, 



The following distinctive forms *owmg ^epticidal U) and loculicidal (S) 



of capsules have been recognised. 



(a) The follicle, consisting of a single carpel, which dehisces along 

 the ventral suture (Paeonia, Aconitum). 



(b) The legume or POD, consisting of a single carpel, which, 

 however, dehisces along both the ventral and dorsal suture (Pea, Bean, 

 and many other Leguminosae). 



(c) The SILIQUA, consisting of two carpels, which separate at 

 maturity, leaving a persistent partition wall (the majority of the 

 Cruciferae, e.g. Capsella bursa pastoris). 



(d) The pyxidium, opening at maturity with a lid-like valve 

 (Anagallis, Hyoscyamus). 



II. Dry Indehiscent Fruit. — This type comprises fruits with a dry 

 pericarp, which neither dehisce at maturity nor break up into separate 

 carpels. Indehiscent fruits with a hard dry pericarp are termed NUTS. 

 An indehiscent fruit containing one seed and having a leathery pericarp 





