ESTIVATION. 279 



purpose by Linnseus ; for no obvious reason except that he had 

 already applied the name of Vernation (the spring state) to express 

 the analogous manner in which leaves are disposed in the leaf-bud. 

 The same terms are employed, and in nearly the same way, in the 

 two cases, but with some peculiarities. As to the disposition of 

 each leaf taken by itself, the corresponding terms of vernation 

 (257) wholly apply to eestivation ; and there are no forms of any 

 consequence to be added, perhaps, except the corrugate or crum- 

 pled, where each leaf is irregularly crumpled or wrinkled, longi- 

 tudinally or transversely, one or both, as happens in the petals of 

 the Poppy and the Helianthemum, a case that is not met with in 

 the foliage ; the induplicate, where the edges are folded inwards, 

 as those of the sepals of Clematis (Fig. 357), but this, as com- 

 pared with vernation is only a modification of the involute ; and 

 the reduplicate, where the margins are bent outwards instead of 

 inwards, as in the corolla of the Potato, which is a mere modifi- 

 cation of the revolute in vernation. 



491. The arrangement in the bud of the several members of the 

 same floral circle in respect to each other is of much importance 

 in s}'stematic botany, on account of the nearly constant characters 

 that it furnishes, and still more in structural botany, from the aid it 

 often affords in determining the true relative superposition or suc- 

 cession of parts on the axis of the flower, by observing the order in 

 which they overlie or envelope each other ; for every enveloping 

 part is almost necessarily external to, or of lower insertion than, 

 the part enveloped. The various forms of aestivation that have 

 been distinguished by botanists may be reduced to three essential 

 kinds, namely, the imbricative, the contorted or convolutive, and 

 the valvular.* 



492. Imbricative aestivation, in a general sense, comprises all 

 the modes of disposition in which some members of a floral circle 

 are exterior to the others, and therefore overlie or inclose them in 

 the bud. This must almost necessarily occur wherever the parts 

 are inserted at distinguishably different heights, and is the natural 

 result of a spiral arrangement. The name is most significant 



* We should properly say of the (Estivation that it is imbricativc, convolu- 

 tive, valvular, &c., and of the calyx and corolla, or of the sepals, &c., that 

 they are imbricate, or imbricated, convolute, valvate, &c., in estivation ; but 

 such precision of language is seldom attended to. 



