CHAPTER VI 

 THE STRUCTURE OF SEEDS 



Vocabulary 



Immature, not fully developed. 

 Primitive, simple or early form of an organ. 

 Transmit, carry (similar to transport). 

 Modified, changed for different use. 



It is so common a fact that a seed reproduces the whole plant 

 that the wonder of it is often overlooked. In the seed must exist, 

 alive, all the beginnings for the full-grown plant, together with 

 nourishment to start growth and adequate protection. 



The seed, then, is a plant organ which consists of three parts: 

 the immature plant (embryo), stored food, and protective coverings. 



Seed Coats. The outer covering of most seeds is called the 

 testa, and is usually thick enough to protect from injury by contact, 

 moisture, or insects. It may also have special adaptations for 

 dispersal. A second inner thin coat (tegumen) is present in some 

 seeds. 



Since the seed was once a part of the parent plant, it bears a 

 scar on the testa, called the hilunt, which marks this point of 

 previous attachment. Near this scar is usually visible a tiny 

 opening called the micropyle, from two Greek words meaning 

 " little door." This little door has two uses; it lets the pollen 

 enter the seed when it is fertilized (see Chapter XIV), and it lets 

 the young plant out when it begins its growth. 



Kernel. Within these coats is the kernel or, seed proper. It 

 may consist wholly of the undeveloped plant (embryo); or may 

 have, outside the embryo, a store of nourishment called the 

 endosperm. 



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