96 



DISPERSAL OF SEEDS 



agency of the wind, the fruits or seeds are very small; or 

 they oppose a large surface to the wind. The large surface 

 may be merely due to the flattened form of the fruit or seed, 

 or it may be caused by the possession of wings 

 or tufts of hair. It is to be noted that when 

 fruits (or their carpels in the case of schizocarps) 

 are closed and indehiscent, they (or the meri-~ 

 carps) are the parts scattered, and adapted to 

 aid dispersal ; the seeds in this case are passively 

 borne inside the fruits. But if the fruit dehisces, • 

 or is open {e.g. Gymnosperms), the seeds are 

 the parts scattered, and, as a rule, it is they 

 and not the fruits which are adapted for transference to 

 distant spots. The following table shows the corresponding 

 mechanisms, or forms, in fruits and seeds to aid dispersal 

 by the wind : — 



Fig. 130. — Samara 

 of Elm. 



Dispersal by clinging to Animals. — Many fruits possess 

 hooks, or rough or sticky surfaces, which cause them to adhere 

 to animals which happen to brush against them. It is usually 

 the fruit, not the seed, which possesses hooks, etc. As examples 

 may be cited, the "burrs" of the infructescences of many 

 Compositse (Daisy-family), the hooked achenes of Geum, and 

 the fruits of Galium (Goose-grass). 



Seeds dispersed by being transported inside Animals. — 

 It is to be noted that when the seeds or fruits are scattered by 



