ESSENTIAL ORGANS. THE STIGMA. 



221 



ought to subsist between 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 directly 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 

 fall off after fertilization is accomplished, and 

 thus be deciduous. 



456. 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 in- 

 stances, be considered as the placentiferous 

 portion of the carpel prolonged upwards. In 

 Armeria and some other plants, this connec- 

 tion with the placenta cannot be traced. * 05 



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

 some cases, as Asimina triloba, where it is unilateral (fig. 377), and in 

 Plantago saxatilis (fig. 378), 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. It consists of loose cellular tissue, and secretes a viscid 

 matter which detains the pollen, and causes it to protrude tubes. 

 This secreting portion is, strictly speaking, the true stigma, but the 

 name is generally applied to all the divisions of the style on which the 

 stigmatic apparatus is situated, as in Labiatae. The stigma usually 

 alternates with the dissepiments of a syncarpous pistil, or corresponds 

 with the cells ; but in some cases, it would appear, that half the stigma 

 of one carpel unites with half that of the contiguous carpel, and thus 

 the stigma is opposite the dissepiments, or alternates with the cells. 

 This appears to be the case in the Poppy, where the stigma of a single 

 carpel is two-lobed, and the lobes are opposite the septa. 



457. If the stigma is viewed as essentially a prolongation of the 

 placenta, then there is no necessary alternation between it and the 

 placenta, both being formed by the margins of carpellary leaves, which 

 in the one case are ovuliferous, in the other stigmatiferous. There is 

 often a notch in one side of a stigma (as in some Rosace*), indicating 

 apparently that it is a double organ like the placenta. To the division 

 of a compound stigma the terms bifid, trifid, &c., are applied according 

 to the number of the divisions. Thus, in Labiataj (fig. 299) and in 

 Composite (figs. 301, 404 s), the stigma is bifid ; in Polemonium, trifid. 

 When the divisions are large, they are called lobes, and when flattened 



Fig. 405. Female flower of Emblica officinalis, one of the Euphorbiaceae. c, Calyx, p p 

 Petals, t, Membranous tube surrounding the ovary, o, Ovary crowned by three styles, s, each 

 being twice bifurcate. 



