STRUCTUEAL BOTANY. 



[45, 46. 



127. The placentae are usually prominent lines or 

 ridges extending along the ventral suture within the 

 cell of the ovary, and bearing the ovules. They are 

 developed at each of the two edges of the carpellary 

 leaf, and are consequently closely parallel when those 

 edges are united, forming one double placenta in the 

 cell of each ovary. 



128. The simple carpel, with all its parts, is completely exemplified in the 

 Pea-pod. When this is laid open at the ventral suture, the leaf form becomes 

 manifest, with the peas (ovules) arranged in an alternate order along each 

 margin, so as to form but one row when the pod is closed. In the pod of 

 Columbine (127), the ovules form two distinct rows, in the simple Plum car- 

 pel, each margin bears a single ovule ; and in the one-ovuled Cherry, only one 

 of the margins is fruitful. 



117, Simple pistil of Strawberry, the style lateral. 118, Simple pistil of Crowfoot, cut to show the 

 ovule. 119, Simple pistil of the Cherry. 120, Vertical section showing the ovule (o), style (s), stigma (a). 

 121, Cross-section of the same. 122, Compound pistil of Spring-beauty. 123, Cross-section of the same, 

 showing the three cells of the ovary. 124, Expanded carpellary leaf of the Double Cherry. 125, The same 

 partly folded, as if to form a pistil. 



129. The stigma is the glandular orifice of the 

 ovary, communicating with it either directly or 

 through the tubiform style. It is usually globular 

 and terminal, often linear and lateral, but subject to 

 great variations in form. It is sometimes double or 

 halved, or 2-lobed, even when belonging to a single 

 carpel or to a simple style, as in Linden, where these 

 carpels are surmounted by three pairs of stigmas. 



130. The compound pistil consists of the united 

 circle of pistils, just as the moruopetalous corolla con- 



