THE FRUIT. 



143 



Fig. 200. 



Fig. 199. 



hard-walled woody cells closely packed together. That 



prickles are really trichomes is shown hy the fact that 



when the bark is stripped off they 



come away along with it. Spines, on 



the other hand (Fig. 200), are lateral 

 outgrowths of the stem. 

 They are, in fact, gener- 

 ally stunted branches, and 

 will be found to spring 

 originally from the axils 

 of leaves. Occasionally 

 the petiole of a leaf is 

 converted into a spine, which then becomes a 

 true phyllome. Ovules are generally regarded 

 as trichomes since they arise from the inner 

 surface of the carpels. 



228. The Fruit. In coming to the consideration of 

 the fruit, you must for the present lay aside any popular 

 ideas you may have acquired as to the meaning of this 

 term. You will find that, in a strict botanical sense, 

 many things are fruits which, in the language of common 

 life, are not so designated. For instance, we hardly speak 

 of a pumpkin or a cucumber as fruit, and yet they are 

 clearly so, according to the botanist's definition of that 

 term. A fruit may be defined to be the ripened pistil 

 togetlier with any other organ, such as the calyx or 

 receptacle, which may be adherent to it. This definition 

 will, perhaps, be more clearly understood after a few speci- 

 mens have been attentively examined. 



229. For an example of the simplest kind of fruit let 



Fi. 199. Prickles of Sweet Brier. Fig. 200. Spines of the Hawthorn. 



