356 AUTOGAMY. 



both filaments and styles are sharply bent over towards the floral receptacle. After 

 the expansion of the petals, the filaments straighten out and together constitute a 

 sheaf of filiform stalks, each of which bears an anther covered with pollen. A little 

 later it is the turn of the styles to become erect. They perform the same move- 

 ments as have previously been executed by the stamens, and push themselves into 

 the midst of the stamens. By these evolutions the stigmas of the longer styles are 

 placed a little above the anthers, whilst those of the shorter styles are brought into 

 direct contact with the anthers, and take from them some of the pollen of which 

 there is always a certain quantity left so that autogamy invariably ensues. 



The method of self-fertilization adopted by the Sun-dew (Drosera) is somewhat 

 like that just described. In Drosera the spherical ovary supports three styles, each 

 of which divides into two spatulate lobes bearing the stigmatic tissue on their 

 upper surfaces. The open flower is cup-shaped, and in it these lobes may be seen 

 spread out horizontally like the spokes of a wheel (see fig. 279^*^, p. 279). The 

 stamens, on the other hand, are erect, and cross the lobes at right angles, holding 

 the anthers above the stigmatic tissue. As soon as the petals begin to close, the 

 stigmatic lobes rise up until they touch the anthers. 



In several Labiates and Lentibulariacese autogamy is dependent on inflections, 

 not of the style but of the stigma. This occurs, for instance, in the Hemp-Nettle 

 (Galeopsis ochroleuca, G. Tetrahit, &c.), where the flowers are protandrous, and so 

 adapted as to ensure cross-fertilization in the event of insects visting them. 

 Towards the end of the flower's period of bloom the stigmatic extremity of the 

 lower arm of the style bends downwards and backwards until it touches the pollen- 

 coated anthers of the longer stamens; in the case of many species of the Wound- 

 wort genus (Stachys palustris, S. sylvatica, &c.) both stigmatic arms bend down 

 a short time before the flower fades and take the pollen from the anthers. The 

 flowers of the Butterwort {Pinguicula; already described at vol. i. p. 142), which 

 face sideways, contain two ascending stamens terminating in patelliform antliers, 

 and above them an egg-shaped ovary surmounted by a large lobate sessile stigma. 

 The lower border of the stigma which bears the receptive tissue hangs down like 

 a curtain over the anthers. Insects, in the act of inserting their probosces into the 

 honey-containing spur, brush first against this stigmatic border, and next against 

 the anthers behind it. Thus they dust the stigma with the pollen they bring from 

 other flowers, and the next moment load themselves with a fresh store which they 

 carry ofl" to yet other plants. The conditions are, in the first instance, adapted to 

 cross-fertilization, and very frequently this form of reproduction occurs in the 

 plants in question; but if no insects visit a flower the pendent stigmatic border rolls 

 up sufficiently to bring the receptive tissue against the anthers. There being still 

 plenty of pollen on the anthers, autogamy is then certain to ensue. The same 

 phenomena may be observed in flowers of the Bladder- wort {Utricular ia), and 

 probably in those of the majority of Lentibulariacese. 



A comparatively rare method of autogamy is for both filaments and style to coil 

 up in spirals and become entangled just before the flower fades, the stigmas being 



