. A class-book of botany; designed for colleges, academies, and other seminaries ... illustrated by a flora of the northern, middle, and western states; particularly of the United States north of the capitol, lat. 38 3/4 o. Botany; Plants -- United States; Plants -- Canada. OVULES. 43 87. The placentas are developed at each of the two edges of the carpellary leaf If these edges be in their normal condi- tions, that is, united, there will be apparently but one placenta to the carpel, and that central. But if the edges be separate, there will necessarily be two placent^e to each carpel, the one
. A class-book of botany; designed for colleges, academies, and other seminaries ... illustrated by a flora of the northern, middle, and western states; particularly of the United States north of the capitol, lat. 38 3/4 o. Botany; Plants -- United States; Plants -- Canada. OVULES. 43 87. The placentas are developed at each of the two edges of the carpellary leaf If these edges be in their normal condi- tions, that is, united, there will be apparently but one placenta to the carpel, and that central. But if the edges be separate, there will necessarily be two placent^e to each carpel, the one to the right and the other to the left of the dorsal suture and style. They are then said to be parietal {paries, a wall).. FIG. 11. — 1, Cross section of a one-celled, three-carpelled ovary with parietal placentas, the dissepiments partially obliterated ; 2, dissepiments wholly obliterated; 3, dissepiments obliterated, showing a free central placenta; 4, a five-celled ovary with 5 false dissepiments, as in the flax; 5, vertical section of an ovary with parietal placentoE; 6, with free central pla- centae ; 7, an amphitropous ovule; 8, vertical section of the same; a, funiculus; 6, raphe; c, chalaza; </, nucleus ; e, secundine ; f, primine ; g, micropyle ; 9, anatropous ovules at- tached to the ovar)'. 88. But the placenta? are sometimes found in the common centre when there are no dissepiments (Fig. 11; 3,6). This anomaly, which is called a free central placenta, is thus ex- plained. The dissepiments were at first actually formed in the usual manner, but afterwards, by the rapid expansion of the shell, they were torn away and obliterated. a. As the ovules are always developed by the placentoe, they, of cotirse, grow out of the margins of the carpellaiy leaf, and are, therefore, understood to be analogous to buds. For, in the Bryophyllum, and some other plants, the true leaves do habitually develop buds at their margins (Fig. 10; 8), and in the mign- ionette the ovules the
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Keywords: ., bookcentury1800, bookdecade1840, bookpublisher, booksubjectbotany
