Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . orolla of the Linden; in which the same bunch of blossoms often furnishes in-stances of regular quincuncial imbrication, of the modification herereferred to, and of a similar disposition of the fifth petal, throwingone of its edges outwards also. If the first petal were also to par-take of this slight obliquity, the imbricative would be completelyconverted into what is variously named 498. The contorted, twisted, or con
Introduction to structural and systematic botany, and vegetable physiology, : being a 5th and revedof the Botanical text-book, illustrated with over thirteen hundred woodcuts . orolla of the Linden; in which the same bunch of blossoms often furnishes in-stances of regular quincuncial imbrication, of the modification herereferred to, and of a similar disposition of the fifth petal, throwingone of its edges outwards also. If the first petal were also to par-take of this slight obliquity, the imbricative would be completelyconverted into what is variously named 498. The contorted, twisted, or convolutive aestivation (Fig. 439,441, the corolla, and 442). In this mode, the leaves of the circle areall, at least apparently, inserted at the same height, and all occupythe same relative position: one edge of each, being directed ob-liquely inwards, is covered by the adjacent leaf on that side, whilethe other covers the corresponding margin of the contiguous leaf onthe other side. This is owing to a torsion or twisting of each memberon its axis early in its development; so that the leaves of the floralverticil, instead of forming arcs of a circle, or sides of a polygon. having for its centre that of the blossom, severally assume an obliquedirection, by which one edge is carried partly inward and the otheroutward. This contorted aestivation is rare in the calyx, but com- FIG. 440. Diagram of the plan and restivation of the flower of the Linden. FIG. 441. Diagram of the imbricated calyx of Wallflower (two outer and two inner sepals),and within the strongly contorted or convolute corolla. 442. Corolla of the latter more Cross-section of the plaited tube of the corolla of Campanula. 444. Similar section of theplaited and supervolute corolla of CoutoIvuIus. AESTIVATION OB PR;EFLORATION. 273 mon enough in the corolla. When this obliquity of position is stromr,the petals themselves are usually oblique, or unequal-sided, from thelesser growth of the overlapped side. This is
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Keywords: ., bookauthorgra, bookcentury1800, bookdecade1860, booksubjectbotany
