34 



ELEMENTS OF BOTANY. 



Bearing in mind, however, that all the floral organs are but trans- 

 formed leaflets of leaf-buds, it is not difficult to understand the structure 

 of the pistil. Let us take, for example, a pea-pod, which is only a simple 

 pistil that has been fertilized and undergone subsequent development, 

 without any essential change of form. Split it open on the side to which 

 the seeds are attached and spread it out as nearly flat as possible. We ob- 

 serve, then, that it has the general form of a leaf with a stalk like a petiole 

 and a mid-vein which continues to the apex, while on the margins are placed 

 the seeds. Now this pod is but an altered leaflet, which was folded in- 

 ward and united at the margins, and had developed along this line of 



Fig. 62.— A pistil. 



o is the ovary, sty. 



the etyle, stig. the 

 Fig. 61 .-A ray floret of a head Bt] . gma> The Qvary 



(compound flower). regtg npon the re _ 



ceptacle (r), which 

 terminates the pe- 

 duncle O). 



Fig. 60.— A disk or tubular floret of a head (compound flower), showing the anthers united into one set 

 (syngenesious). Magnified. 



union a number of ovules. At the apex the stigma was placed, and 

 through this fertilization was effected, as will be seen later. Such is the 

 general plan upon which the simple pistil is constructed ; but as the 

 leaves of plants exhibit an endless variety of forms, so naturally would the 

 leaflets whose transformations produce pistils, and hence the pistils also. 

 Again, the pistils are very often compound— that is, made up of from two to 

 many simple ones grown together. Suppose, for example, a circle of five 

 leaflets stand in the centre of a bud, which are to be transformed into a 

 compound pistil. The margins of each would be folded in and united, to 

 form simple pistils ; then the sides of each, coalescing with those of its 



