30 BOTANY. 



gynizus. The individual carpels composing a pistil may be arranged like 

 leaves, either in a whorl, or along a spiral. When they remain separate 

 and distinct, the pistil is apocarpous ; when the carpels are all united, the 

 pistil is sijncarpous ; when the union of the carpels takes .place by the 

 ovaries alone, leaving the styles and stigmas free, the pistil is gamogastrous, 

 and the ovary compound. The number of parts in a syncarpous pistil may 

 be determined by the external venation, the grooves on the outside, and the 

 internal divisions of the ovary. When the grooves between the carpels are 

 deep, the ovary is said to be lohed. The carpels, although generally sessile, 

 are sometimes petioled and elevated above the surrounding Avhorls. The 

 union of these petioles constitutes a stipitate pistil ; or Avhen thickened and 

 somewhat succulent, a gynophore, or thccaphore ; when the axis is 

 produced beyond the ovaries, and the styles are united to it, we have a 

 carpophore. 



The ovules are developed on the inner side of the carpel, where the two 

 edges of the carpellary leaf unite. The attachment to the edge, according 

 to some authors, but doubted by others, is effected by vascular tissue, which 

 traverses the carpel and sends off a branch to each ovule. At the same 

 place there is a development of cellular tissue connected Avith the conducting 

 tissue of the style and with the stigma. The union of these two tissues 

 constitutes the placenta or projection to which the ovules are attached ; 

 those who restrict this term to the individual branch of each ovule, style it 

 the jilacentary, or the pist'dlary cord. Tlie placenta marks the ventral or 

 tinner suture of the carpel, the outer or dorsal suture corresponding to the 

 midrib of the carpellary leaf The placenta is formed on each margin or 

 edge of the carpel, and hence it is essentially double, although sometimes 

 appearing single ; in an apocarpous pistil there are generally separate 

 placentas on each margin. In the syncarpous, however, the edges of 

 contiguous carpels unite to form a septum or dissepiment. When the 

 dissepiments extend to the centre or axis, the ovary is divided into cavities, 

 cells, or loculaments : it may be bilocular, trilocular, quadrilocular, (fee, as 

 there are two, three, four, or more cells corresponding to as many carpels. 

 In these cases the marginal placentas meet in the axis, and unite so as to 

 form a central one. This kind of placentation is, perhaps improperly, 

 termed axile. When the dissepiments do not extend to the centre, but 

 merely form a projecting partition, the ovary is unilocular, and the placentae 

 parietal. Sometimes the placentae are not connected with the walls of the 

 ovary, but form a column, standing free in the centre ; in this case we have a 

 free central placenta. In some rare cases the phenomena of placentation 

 are such as to lead las to suppose that the placentae are not marginal, or on 

 the edges of the carpellary leaves, but rather a.rile, that is, prolongations of 

 the axis, the ovules being lateral buds, and the carpels verticillate leaves 

 united together around the axis. 



Divisions in ovaries, not formed by the edges of contiguous carpels, are 

 called spurious dissepiments. These, when horizontal, are termed phrag- 

 mata. The prolongation of the edges of the placentae in a rephmi sometimes 

 subdivides the ovary. 

 30 



