ESSENTIAL ORGANS — THE PISTIL, 237 



plained under fertilisation. Lindley has shown that in some instances 

 the style seems to derive its origin from the placenta. The presence 

 of the style is by no means essential to the perfection of the pistil. It 



Pig. 40S. 



Pig. 409. 



varies in its shape and position, being usually apicilar, but from altera- 

 tion in the direction of the central axis it occasionally seems to be' 

 lateral. Its form and appearance 

 also vary ; under ordinary cir- 

 cumstances it is rounded in shape, 

 but occasionally becomes flattened, 

 as in the Iris. In Clematis it is 

 furnished with hairs ; in Euphorbia 

 it is forked. 



The Stigma is a continuation of 

 the cellular tissue in the centre of 

 the style, and it may be either ter- 

 minal, when the canal opens at the 

 top only (figs. 407 «, 410, 1), or 

 lateral, when the splitting of the 

 canal takes place on one side (fig. 

 411 s), or on both sides (fig. 412 s s). 

 along the whole length of the style. 



Fig. 410. Fig. 411. Fig. 412. 



The stigma sometimes extends 

 In other instances the style is 



absent, and then the stigma is said to be sessile. In Orchideous plants 



Fig. 408. Tfansveree section of tlie style of Fritillaria imperialis, or Crown Imperial. 

 The style is composed of three united together, v v v, Three vascular bundles, each 

 corresponding to one of the three styles, p, Papillae or cellular bodies projecting into the 

 cavity of the canal. Fig. 409. Structure of the canal in the centre of the style of a 

 Campanula, c c. Cellular tissue forming its paiietes traversed by trachea, v. p p. Variously 

 formed cells, displaced as it were, and along with other elongated and filamentous ones, //, 

 obstructing the canal. Fig. 410. 1, Stigma, 5, of Daphne Laureola, terminating the st^le, 

 t. 0, Summit of the ovary. 2. A small portion of the surface of the stigma, much magnified 

 to show its papillas. Fig. 411. Unilateral stigma, s, of Asimina triloba, i, Style. Fig. 

 412. Bilateral stigma, s s, of Plantago saxatilis. o. Ovary. *, Style. 



