124 COMPOUND ORGANS OP PLANTS. 



each other, which have the appearance of a continuous primary 

 axis ; but the flowers which appear lateral are in reality all 

 terminal. 



As might be expected, all these forms of inflorescence pass 

 into each through endless intermediate gradations. In nature 

 they are not so absolutely fixed as in our written definitions, 

 and whether this or that name should be used in a particular 

 case, is often a matter of fancy. 



The manner in which the leaves of the flower are arranged 

 in the bud, before the expansion of the flower, is called their 

 aestivation, (sestivus belonging to summer,) or prsefloration, 

 (pree, before, and flos, flower.) These terms bear the same 

 relation to the flower bud that vernation does to the leaf bud ; 

 and indeed, since the flower bud is only a modified leaf bud, as 

 might be expected, the corresponding terms applied to vernation 

 are used in reference to praefloration or aestivation. A few 

 new terms are however added, descriptive of certain peculiar 

 modifications in the general forms described in vernation. 

 Fig. 31. Fig. 32. 



Fig. 32. The flower bud of Althsea rosea, showing the valves of the calyx, c, opened, 

 and the contorted praefloration of the petals of the corolla, p. 



The following are the principal forms of aestivation to which 

 the others are generally reducible.* 



