STRUCTURAL BOTANY. 55 



nolia, Strawberry, etc. 



Pistils are either simplb or compound. 



105. A SIMPLE PISTIL consists (as was stated in § 47) 

 of the transformed blade of a carpellary leaf. The inner 

 surface of the ovary answers to the upper surface of the 

 leaf, and the style or stigma to its apex, rolled together. 

 The line of the pistil, which was formed by the union of 

 the edges of the leaf, is called the inner or ventral suture, 

 a true seam, and always faces the axis of the flower. The 

 opposite line, answering to the midrib of the leaf, is 

 either obsolete (not at all, or scarcely perceptible), or con- 

 spicuous as a thickened stripe ; this we call, though im- 

 properly, the outer or dorsal suture. 



That part of the ventral suture within the ovary, to 

 which the ovules are attached, and which commonly 

 forms a projection, is called the jplacenta. The placenta 

 is the ovule-hearing jpart of the inside of the ovary, and 

 consists of two parts, one belonging to each edge of the 

 transformed leaf. Hence, it is usually two-lobed or two- 

 ridged. According as the union of the edges of the leaf 

 is more or less perfect, the double nature of the placenta 

 will be more or less obvious. When a pea-pod is laid 

 open, the ovules or peas will be found in alternate order 

 along each edge, so as to make but one row, when the 

 pod is closed. In Aquilegia, on the other hand, the pods 

 have their seeds arranged in two rows very conspicuously. 

 Sometimes only one ridge of the placenta is fruitful, as in 

 the one-seeded Cherry. 



A simple pistil can have hit one cell, one placenta, one 

 style, one stigma. The fact, that a simple pistil is one- 

 celled, does not imply that all single-celled pistils are 

 simple, since many compound pistils are one-celled. The 

 stigma may be 'two-crested, or even two-lobed. It is 



