258 THE SEED PLANTS : FORMS AND LIFE HISTORIES 



the terminal bud is produced between the two cotyledons. 

 This consists of an apical (primary) shoot meristem 

 bearing the rudiments of leaves on its sides. It grows 

 out into the main shoot of the seedUng (epicotyl), the 

 stem elongating and the leaves developing and unfolding. 

 The levels of the stem from which a leaf (or a pair or 

 whorl of leaves) actually arise are called nodes, and 

 the bare stretches of stem between the nodes are inter- 

 nodes. Branches of the shoot are developed from 

 lateral buds, which are nearly always developed in the 

 angle between a leaf and the internode above the leaf 

 {axil of the leaf), and are hence called axillary buds. 

 Each axillary bud repeats the structure and develop- 

 ment of the terminal bud. A bud is maintained at the 

 tip of the main axis and at the tip of each branch 

 (terminal buds of the branches), the meristem being 

 constantly renewed by cell division as its products 

 develop into mature tissue. 



Eventually flowers are produced. These are parts 

 of the shoot or separate shoots (i.e. the whole product 

 of a lateral bud) bearing specialised leaves (floral 

 leaves), some of which produce the gametes. Sometimes 

 one flower is produced from the terminal bud, generally 

 a larger number from various axillary buds. A bud 

 which is forming floral leaves is called a flower bud. 

 After the flowers have opened, conjugation of the 

 gametes produced by the floral leaves has taken place, 

 and the zygotes have grown into embryos within the 

 seeds, which are contained in the modified remains of 

 the flower called the fruit, the whole of the vegetative 

 part of an annual plant — the entire root and shoot — 

 dies, the life of the species being continued solely in 

 the seeds, which under favourable conditions in due 

 course germinate to form new plants. 



