60 THE FLOWER. 



§8. OF iESTIVATION. 



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

 botanists, to denote the 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 wholly rolled in another, as in the 

 petals of the wall-flower. 



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

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

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

 terior, as in Rosa. 



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

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

 hke manner, overlapped by that wliich 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 Lihacese. 



FIG. 15. — -SIstivation of the corolla; 1, Hydrangea; 2, Cheiraiithus ; 3, Rose (single); 

 4, Oxalis ; 5, Lilium ; 6, Pisum ; 7, Lysimachia ; 8, Solauum ; 9, calyx of the Rose. Tha 

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



