ELEMENTS OF STRfCTURAL UOTANY. 03 



instance, is the mistake of cousidoriug the entire 

 carpel to be merely a seed. It is a seed envel- 

 oped in an outer covering which we called the ovary 

 in the early stages of the flower, but which, now 

 that it is rii^e, we shall call the pericarp. This pericarp, 

 with the seed which it contains, is the fruit. The prin- 

 cipal difference between the fruit of Marsh-Marigold 

 and that of Buttercup is, that, in the former, the peri- 

 carp envelopes several seeds, and, wlien ripe, splits open 

 down one side. The fruit of Buttercup does not thus 

 split open. In the Pea, again, the pericarp encloses 

 several seeds, but splits open along hotfi margins. The 

 fruits just mentioned all result from the ripening of 

 apucarpoiis pistils, and they are consequently spoken cf 

 as apoca rpo us fru i fs. 



146. In Willow-herb, you will recollect that the 

 calyx tube adheres to the whole surface of the ovary. 

 The fruit in this case, then, must include the calyx. 

 When the ovary ripens, it splits longitudinally into four 

 pieces (Fig. 41), and, as the pistil was sijncarpnus, so 

 also is the fruit. 



147. In the I'each, Plum, Cherry, and .tfone-j'mlt.'i or 

 drupes generally, the seed is enclosed in a hard 

 shell called a putnmen. Outside the putamen is 

 a thick layer of pulp, and outside this, enclosing 

 the whole, is a skin-like covering. In these fruits 

 all outside the seeds is the pericarp. In one 

 respect these stone-fruits resemble the fruit of the 

 Buttercup : they do not split open in order to discharge 

 their seeds. All fruits having this pecuharity are said 

 to be indehiscent, whilst those in wliich the pericarp 

 opens, or separates into pieces (called lalres), are de- 

 hiscent. 



