STRUCTURE OF FRUITS 



215 



are called samaras. Other examples are the Maple, Ash, 

 Elm, and Birch. 



Another common type which splits into two half-fruits 

 is found in the Hogweed, Chervil, and other umbelliferous 

 plants. A ripe fruit of the Hogweed (Fig. 148) is easy to 

 dissect. It consists of two flattened carpels, which readily 

 separate into two half-fruits (mericarps), and remaining 

 attached by a slender stalk, the carpophore (c), each 



Fig. 150. 1, Siliqua of Shep- 

 herd's Purse ; 2, siliqua de- 

 hiscing ; r, replum with seeds 

 attached. 



Fig. 149. 

 Follicles of Columbine. 



mericarp containing one seed. Such fruits are called 

 cremocarps. Caraway ' seeds ' are half-fruits of this kind. 



Dry dehiscent fruits. In all the above, when the fruit is 

 dispersed, the thick protective coat does not burst until 

 germination begins, such seeds usually having only a thin 

 testa. Dry fruits of a second class have a fruit-coat which 

 splits, and so allows the seeds to escape. These, not having 

 the protection of the fruit-coat, are usually surrounded by 

 a thick testa. They include many common fruits, and 

 several should be examined, and the different modes of 

 splitting (or dehiscence) compared. 



The Columbine (Fig. 149), Monkshood, and Marsh 



