. Introduction to structural and systematic botany, and vegetable physiology. Botany. K^^|, even in the same natural family of plants, where it cannot be doubt- ed that the blossoms are constructed upon a common plan in all the species. Even in the family Crassulaceai, for example, where the flowers are remarkably symmetrical, and from ^" which our pattern flowers, Fig. 334 and 353, are derived, a considerable number of these di- versities are to be met with. In Crassula, we have the completely symmetrical and simple pentamerous flower (Fig. 359, 360), viz. with a calyx of five sepals, a
. Introduction to structural and systematic botany, and vegetable physiology. Botany. K^^|, even in the same natural family of plants, where it cannot be doubt- ed that the blossoms are constructed upon a common plan in all the species. Even in the family Crassulaceai, for example, where the flowers are remarkably symmetrical, and from ^" which our pattern flowers, Fig. 334 and 353, are derived, a considerable number of these di- versities are to be met with. In Crassula, we have the completely symmetrical and simple pentamerous flower (Fig. 359, 360), viz. with a calyx of five sepals, a corolla of five petals alter- nate with the former, an androecium (418) of five stamens alternating with the petals, and a gynaseium (419) of five pistils, which are alter- nate with the stamens ; and all the parts are regular and symmetrical, and also distinct and free from each other ; except that the sepals are somewhat united at the base, and the petals and 360 stamens slightly connected with the inside of the calyx, instead of arising directly from the recep- tacle or axis, just beneath the pistils. Five is the prevailing or noi-mal number in this family. Nevertheless, in the related genus TillEea, most of the species, like ours of the United States, have their parts in fours, but are otherwise similar, and one common European species has its parts in threes (Fig. 353) ; that is, one or two members are left out of each circle, which of course does not in- terfere with the symmetry of the blossom. So in the more conspic- uous genus Sedum (the Stonecrop, Live-for-ever, Orpine, &c.), some species have their parts in fives ; others in fours ; and several, like our S. ter- natum, have those of the first blossom in fives, but all the rest in fours. But Sedum also illustrates the case of reg- ular augmentation (447, 1st) in its an- droecium, which consists of twice as many stamens as there are members in the other parts ; that is, an addi- ^" tional circle of stamens is
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Keywords: ., bookauthorgra, bookcentury1800, bookdecade1850, booksubjectbotany
