ESSENTIAL ORGANS. THE PISTIL. 



213 



axis is produced beyond the ovaries, and the styles become united to 

 it, as in Geraniaceae and Umbellifera. In this case the prolongation 

 is called a carpophore (*g7ro$, fruit, and Qogsu, I 

 bear). 



438. The ovules are developed on the inner side 

 of the carpel where the two edges of the carpellary 

 leaves unite, and they are connected to it by vas- 

 cular bundles which proceed from below upwards, 

 traverse the carpel, and send a branch to each of 

 the ovules. At the same place there is a develop- 

 ment of cellular tissue in connection with the con- 

 ducting tissue of the style and with the stigma. By 

 the union of these tissues is formed the placenta, 

 or projection to which the ovules are attached. 

 Some restrict the term placenta to the point of 

 attachment of a single ovule, and call the union of 

 placentas, bearing several ovules, placentaries or 

 pistillary cords. The part of the carpel where the 

 placenta is formed, is the inner or ventral suture, cor- 

 responding to the margin of the folded carpellary 385 

 leaf, while the outer or dorsal suture corresponds to the midrib of the 

 carpellary leaf The placenta is hence sometimes called marginal. 

 The placenta is formed on each margin of the carpel, and hence is 

 essentially double. This is seen in cases where the margins of the 

 carpel do not unite, but remain separate, and consequently two pla- 

 centas are formed in place of one. In fig. 386, the two carpels are 

 folded, so that their margins meet, and the placenta is apparently 

 single; whereas in fig. 387 the margins of each carpel do not meet, 



and the placenta of each is double. Again, in fig. 388, the two carpels, 

 after meeting in the centre or axis, a, are reflected outwards towards 

 the dorsal suture, s d, and their margins separate slightly, each being 

 placentary and bearing ovules, o. 



439. When the pistil is formed by one carpel, the inner margins 

 unite in the axis, and form usually a common marginal placenta. 



Fig. 385. Section of monstrous Rose, as figured at section 324, the axis of which is prolonged 

 beyond the flower, and the envelopes removed to show the abortivei stamens, r. The carpels 

 are attached alternately along the axis in the form of leaves, p, Abortive floral envelopes, 

 c, Stamens in imperfect flower at the apex. 



Figs. 386, 387, 388. Horizontal sections of ovaries, composed of two carpellary leaves, the edges 

 of which are folded so as to meet in the axis, a, in fig. 387 ; are reflected inwards into the locu- 

 laments after meeting in the axis in fig. 388 ; and do not reach the axis in fig. 387. 



