SECTION 8.] ARRANGEMENTS IN THE BUD. 



97 



275. In Violets (Fig. 238, 276), the odd sepal is posterior (next the 

 axis) ; the odd petal is therefore anterior, or next the subtending leaf. In 

 the papilionaceous flower (Fig. 261, and diagram, Fig. 275), the odd sepal is 

 anterior, and so two sepals are posterior; consequently, by the alternation, 

 the odd petal (the standard) is posterior or upper, and the two petals form- 

 ing the keel are anterior or lower. 



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$ 5. ARRANGEMENT OF PARTS IN THE BUD. 



276. .^Estivation was the fanciful name given by Linnseus to denote 

 the disposition of the parts, especially the leaves of the flower, before An- 

 thesis, i. e. before the blossom opens. Prcefloration, a better term, is some- 

 times nsed. This is of importance in distinguishing different families or 

 genera of plants, being generally uniform in each. The aestivation is best 

 seen by making a slice across the flower-bud ; and it may be expressed in 

 diagrams, as in the accompanying figures. 



277. The pieces of the calyx or the corolla either overlap each other in 

 the bud, or they do not. When they do not overlap, the aestivation is 



Valvate, when the pieces meet each other by their 

 abrupt edges, without any infolding or overlapping; 

 as the calyx of the Linden or Basswood (Fig. 277). 

 Induplieate, which is valvate with the margins of 

 each piece projecting inwards, as in the calyx of a 

 common Virgin's-bower, Fig. 278, or 



Involute, which is the same but the margins rolled 

 inward, as in most of the large-flowered species of 

 Clematis, Fig. 279. 

 Reduplicate, a rarer modification of valvate, is similar bat with margins 

 projecting outward. 



Open, the parts not touching in the bud, as 

 the calyx of Mignonette. 



278. When the pieces overlap in the bud, it 

 is in one of two ways ; either every piece has 

 one edge in and one edge out, or some pieces 

 are wholly outside and others wholly inside. In 

 the first case the aestivation is 



Convolute, also named Contorted or Twisted, as in Fig. 280, a cross-sec- 

 tion of a corolla very strongly thus convolute or rolled up together, and in 

 the corolla of a Flax-flower (Fig. 281), where the petals only moderately 

 overlap in this way. Here one edge of every petal covers the next before 



277 



Fig. 277. Diagram of a flower of Linden, showing the calyx valvate and corolla 

 Imbricate in the bud, etc. 



Fig. 278. Valvate-induplicate estivation of calyx of common Virgin's-bower. 

 Piu. 279. Valvate-involute aestivation of same in Vine-bower, Clematis Vitialla. 



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