144 ELEMENTS OP STRUCTURAL BOTANY. 



us revert to our Buttercup. As the carpels ripen, the 

 style and stigma are reduced to a mere point. On cutting 

 open one of these carpels when fully ripe, we iind it 

 contains a single seed, not quite filling the cavity, but 

 attached at one point to the Avail of the latter. What you 

 have to guard against, in this instance, is the mistake of 

 considering the entire carpel to be merely a seed. It is a 

 seed enveloped in an outer covering which .we called the 

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

 that it is ripe, we shall call the pericarp. This pericarp, 

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

 principal difference between the fruit of Marsh Marigold 

 and that of Buttercup is that, in the former, the pericarp 

 envelopes several seeds, and, when 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 both margins. The fruits just mentioned 

 all result from the ripening of apocarpous pistils, and they 

 are consequently spoken of as apocarpous fruits. 



230. 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 syncarpous^ so also is the 

 fruit. 



231. In the Peach, Plum, Cherry, and stone-fruits or 

 drupes generally, the seed is enclosed in a hard shell 

 called aputamen. 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 resemMo the 



