260 



LESSONS WITH PLANTS 



that one -seeded fruits are indehiscent, but many- 

 seeded fruits are usually dehiscent. That is, the 

 seed of the akene and drupe is lib- 

 erated from the outer covering by 

 rupture or decay of the pericarp. 



304. The dehiscence, or open- 

 ing, of the fruits of the colum- 

 bine takes place along the inner 

 edge, as in i. We have seen that 

 carpels are akin to leaves. It 

 requires little imagination to sug- 

 gest that the carpel of the col- 

 umbine may represent a leaf 

 rolled inward, and that it splits 

 along the union of the two 

 edges; and this supposition is borne out by much 

 direct evidence. The front or upper side of the 

 leaf- carpel faces inward and the back or under 

 side, or mid -rib, faces outward. The front is 

 known as the ventral side, and the back as the 

 dorsal side. 



Fig. 247. 

 Follicles of columbine. 



304a. The beginner cannot expect to prove that the carpel has 

 actually been developed from a leaf, although he has seen much 

 evidence to show that the parts of the flower may be transformed 

 foliage leaves (recall Obs. xxxvii). The important point to remem- 

 ber here is that floral members and leaves are comparable, and 

 that the best way in which to define and to understand the carpel 

 is to liken it to a transformed leaf. 



