. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. 108 COMPOUND PISTILS. [section 10. Such a pistil is just what would be formed if the simple pistils (two, three, or five ill a circle, as the case may be), lilte those of a Paeony or Stonecrop (Fig. 224, 225), pressed together in the centre of the flower, were to cohere by their contiguous parts. In such a case the placentae are naturally axile, or all brought together in the axis or centre; and the ovary has as many Disse
. Gray's school and field book of botany. Consisting of "Lessons in botany," and "Field, forest, and garden botany," bound in one volume. Botany; Botany. 108 COMPOUND PISTILS. [section 10. Such a pistil is just what would be formed if the simple pistils (two, three, or five ill a circle, as the case may be), lilte those of a Paeony or Stonecrop (Fig. 224, 225), pressed together in the centre of the flower, were to cohere by their contiguous parts. In such a case the placentae are naturally axile, or all brought together in the axis or centre; and the ovary has as many Dissepiments, or internal Partitions, as there are carpels in its composition. Eor these are the contiguous and coalesceut walls or sides of the component carpels. When such pistils ripen into pods, they often separate along these lines into their elementary carpels. 311. One-celled, with free Central Placenta. The commoner case is that of Purslane (Fig. 272) and of the Pink and Chickweed families (Pig. 331, 332). This is ex- plained by supposing that the partitions (such as those of Fig. 329) have early vanished or have been suppressed. In- deed, traces of them may often be detected in Pinks. On the other hand, it is equally supposable that in the Primula family the free central is de- rived from parietal placentation by the carpels bearing ovules only at base, and forming a consolidated common placenta in the axis. Mitella and Dionsea help out this conception. 312. One-celled, with. Parietal Placentae. In this not uncommon case it is conceived that the two or three or more carpel-leaves of such a compound pistil coalesce by their adjacent edges, just as sepal-leaves do to form a gamo- sepalons calyx, or petfds to form a gamopetalous corolla, and as is shown in the diagram. Fig. 333, and in an actual cross-sec- tion, Fig. 334. Here each carpel is an open leaf, or with some introflexion, bearing ovules along its margins; and each placenta consists of the con-. FlG. 331, 332. Pistil
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