248 



ESSENTIAL OEGANS — THE STIGMA. 



the style, come into contact with the already ripened pollen, and carry 

 it up along with them, ready to be applied by insects to the mature 

 stigma of other flowers. In Vicia and Lobelia the hairs frequently 

 form a tuft below the stigma. 



The styles of a syncarpous pistil may be either separate or united ; 

 when separate, they alternate with the septa. When united com- 

 pletely, it is usual to call the style simple (fig. 433) ; when the union 

 is partial, then the style is said to be bifid, trifid, muUifid, according 

 as it is two-cleft, three-cleft, many-cleft ; or, to speak more correctly, 

 according to the mode and extent of the union of two, three, or many 

 styles. The style is said to be bipartite, tripartite, or multipwrtite, 

 when the union of two, three, or many styles only extends a short 

 way above the apex of the ovary. The style of a single carpel, or of 

 each carpel of a compound pistil, may also be divided. In fig. 346, 

 2, each division of the tricarpellary ovary of Jatropha Curcas has a 

 bifurcate or forked style, s, and in fig. 439 the ovary of Emblica 

 ofiicinalis has three styles, each of which is divided twice in a bifurcate 

 manner, exhibiting thus a dichotomous division. 



The length of the style is determined 

 by the relation which ought to subsist be- 

 tween the position of the stigma and that 

 of the anthers, so as to allow the proper 

 application of the pollen. In some cases 

 the ovary passes insensibly into the style, 

 as in Digitalis, in other instances there is 

 a marked transition from one to the other. 

 The style may remain persistent, or it may 

 faU. off after fertilisation is accomplished, 

 and thus be deciduous. 



The Stigma is the termination of the 

 conducting tissue of the style, and is usually 

 in direct communication with the placenta. 

 It may, therefore, in most instances, be considered as the placental 

 portion of the carpel, prolonged upwards. In Armeria, and some 

 other plants, this connection with the placenta cannot be traced. Its 

 position may be either terminal or lateral. The latter is seen in some 

 cases, as Asimina triloba, where it is unilateral (fig. 411), and in 

 Plantago saxatilis (fig. 412), where it is bilateral. Occasionally, as 

 in Tasmannia, it is prolonged along the whole inner surface of the 

 style. In Iris it is situated on a cleft on the back of the petaloid 

 divisions of the style. Some stigmata, as those of the Mimulus, 

 present sensitive flattened laminse, which close when touched. The 



Fig. 439. 



Fig. 439. Femaleflowerof Bmtlica officinalis, one of the Enphorbiaceffi. c, Calyx, pp. 

 Petals, tt Membranous tube surromiding the ovary, o. Ovary, crowned by three styles, s, 

 each being twice bifurcate. 



