MORPHOLOGY OF ANGIOSPERMS. 125 



carpels are united the number of dissepiments corresponds to the 

 number of carpels. It sometimes happens that a partition or wall 

 is intruded from the mid-vein of the carpel, dividing a unilocular 

 ovary into one that is bi-locular, as in species of Astragalus, and 

 such a partition is termed a false dissepiment. 



When no other than the true dissepiments exist in the s\n- 

 carpous gynaecium the placentas are borne along the axis of the 

 flower and are termed axial placentas. In the Caryophyllacese 

 the ovules are borne upon a central axis, and the dissepiments 

 having been absorbed the gynaecium is said to possess a free 

 central placenta. In other cases the placentas grow backward 

 from the central axis toward the mid-vein of the carpel, carrying 

 the ovules with them, when they are spoken of as parietal pla- 

 centas, as in colocynth fruit (Fig. 254). 



The Style not only varies in shape and size but in the manner 

 of attachment to the ovary (Fig. 79) ; it may be very short, as in 

 the clove; long and filiform, as in (Enothera; club-shaped (clav- 

 ate) as in the orange ; or broad and petalloid, as in Iris. It is usu- 

 ally situated at the summit of the ovary when it is said to be apical 

 or terminal ; it may, however, be laterally attached, as in the straw- 

 berry, or, as in a few instances, attached to the base of the ovary. It 

 is usually smooth, but may be hairy, as in the Compositae. The styles 

 like the carpels may be separate or united, and in the latter case 

 may have a central canal connecting the stigma with the ovary, as 

 in the violets. While usually deciduous, the style may be more or 

 less persistent forming a part of the fruit or even become much 

 elongated, as in the dandelion. 



The Stigma is an essential part of the pistil in that it is the 

 germinating ground of the pollen grains, it being viscid and espe- 

 cially adapted for this purpose (Fig. 79). The stigmas may be 

 separate, as in the Composite, or they may be united into a more 

 or less club-shaped or globular head, consisting of as many lobes 

 as there are stigmas, as in the poppy. The stigma, while usually 

 solid, may have an opening, as in the violets, which sometimes has 

 a lid-like appendage, as in Viola tricolor. 



The Ovules (Fig. 85), as we have already seen, are small 

 bodies which are borne on the placentas, and which, after fertiliza- 

 tion develop into seeds. The number of ovules varies considerably 



