50 



THE FLOWEll. 



§8. OF ESTIVATION. 



108. ^Estivation (cestivus, of summer) is a term used by- 

 botanists, to denote tlie relative arrangement of the several 

 organs of the flower while yet undeveloped in the bud. It is 

 the same to the flower-bud as vernation {vernus, of the spring) 

 is to the leaf-bud. 



a. The different modes of aestivation may be best observed in sections of the 

 bud, made by cutting it in a horizontal direction. The most common varieties 

 are the following. 



1. Valvate; applied to each other by the margins only; as the 

 petals of the Umbelliferse, the valves of a capsule, &c. 



2. Convolute ; when one is whoUy rolled in another, as in the 

 petals of the wall-flower. 



3. Quincuncial; when the pieces are five in number, of which 

 two are exterior, two interior, and the fifth covers the interior 

 with one margin, and has its other margin covered by the ex- 

 terior, as in E-osa. 



4. Contorted; each piece being oblique in figure, and over- 

 lappmg its neighbor by one margui, its other margin being, in 

 like manner, overlapped by that which stands next it, as 

 the corolla of Apocynum. 



5. Alternative; when, the pieces being in two rows, the inner 

 is covered by the outer in such a way that each of the exterior 

 rows overlaps half of two of the interior, as in the Lihaceae. 



FIG. 15.— Estivation of the corolla; 1, Hydrangea; 2, Cheiranthus; 3, Rose (single); 

 4, Oxalis ; 5, Lilium ; 6, Pisum ; 7, Lysiraachia ; 8, Solanum ; 9, calyx of the Rose. The 

 last form, with 4 and 5, are also termed imbricate. 



