.ESTIVATION. 79 



palled irregvJar, as the pea, catmint, violet, are regular, like other flowers, in the 

 early bud ; that is, the several petals are at first seen to be precisely similar, becom- 

 ing dissimilar and distorted in their after growth ; so in the stamens and other or- 

 gans. 



380. Cases m aetipicial development or teratoloot (jlpa, a monstrosity, 

 Uyo^), where organs of one kind are converted into those of another kind by cul- 

 tivation, afford undeniable evidence of the doctrine in question — (he homology of 

 ail the floral organs with the leaf. Such cases are frequent in the garden, and how- 

 ever much admired, they are monstrous, because unnatural In all double flowers, 

 as rose, pseony, Camillia, the stamens have been reconverted into petals, either 

 wholly or partially, some "yet remaining in every conceivable stage of the transition. 

 In the double butter-oup (242) the pistUs as well as stamens revert to petals, and in 

 the garden cherry, flowering almond, a pair of green leaves occupy the place of the 

 pistils. By still further changes all parts of the flower manifest their foliage affini- 

 ties, and the entire flower-bud, after having given clear indications of its floral char- 

 acter, is at last developed into a leafy branch. (Fig. 243.) 



381. In Claekia, Celastbus, damask rose, and other garden plants, cases have 

 been noted wherein the petal asserts its foliar nature by producing a secondary 

 flower-bud in its axil 1 Thus in a thousand instances of abnormal growth, we find 

 evidence proving the leaf to be the type whence all other forms of appendages are 

 derived, andwhithor all tend to return. 



382. PuBTHEE evidence of this view, equally conclusive, is found in the essen- 

 tial agreement of the aestivation of the flower-bud with the phyllotaxy of the branch. 



.a:STIVATION. 



^"^'383. Definition — impoktanoe. This term (from cestivus, of sum-" 

 mer) refers to the arrangement of the floral envelops while yet in the 

 bud. -It is an important subject, since in- general the same mode of 

 sestivation regularly characterizes whole tribes or orders. It is to the 

 flower-bud what vernation (vernus, spring) is to the leaf-bud.' 



384. The taeious modes of aestivation aee best OBSEEviED in sections of the 

 bud made by cutting it through horizontally when just ready to open. Proin such 

 sections our diagrams are copied. 



885. Sepakatelt considered, we find each organ here folded in 

 ways similar to those of the leaf bud ; that is, the sepal or the petal 

 may be convolute, involute, revolute., etc, terms already defined. 



386. Collectively considered, the sestivation of the flower occurs 

 in four general modes with their variations ; the valvate, the contorted, 

 imbricate, and plicate. 



* 387. In valvate ^estivation the pieces meet by their margins with- 

 out any overlapping ; as in the sepals of the mallow, petals of Hydran- 

 gea, valves of a capsule. The following varieties of the valvate occur : 



388. .Induplicatb, where each piece is involute ; i. e., has its two 

 margins bent or rolled inwards, as in Clematis ; or reduplicate, when 

 each piece is revolute— having its margins bent or rolled outwards, as 

 in the sepals of Althea rosea. (Figs. 245, 246.) 



