GEnXIXOGAMY. oil 7 



p.illini by insect* ocnn-s but soUioni iu this plaint, so that from the xiiaiiy ovaries in 

 tJie infloivsoenoe of Eremurus usually only a few fruits are matured. This is the 

 inoiv remarkable as these flowei-s have remarkably long-lived stigmas, a peculiarity 

 which is generally very advaut^igeous in bringing about oross-pollinatiou. The 

 sii::fnis is already niatuiv when the perianth opens: when the tips of the perianth 

 roll back and assimie the form of aphides tseo p. 1TT\ and when the style moves 

 like the hand of a TvatcJi towards the axis of the iutloreseence. the stigma is still 

 receptive, and remains so even when the style has ag;iin straightened and assumed 

 an oblique xipwjird direction. 



A peculiar instance of geitoitog-amy is observed in AUiu m Victorialir'. Each umbel 

 is comjvsed of flowers of very dilfex^nt ages. Before the lirst liowers bend over. 

 wither, and shrivel up. their pollen-covered axithers project well over the edge of the 

 perianth. In the younger flowers, at the same time, the anthei-s are still closed and 

 ccivercii by the perianth-leaves, but the stigmas are ripe and project beyond tliem. 

 These young and hitherto short-stalked tiowers ai^ now i-aised by the elong;\tion of 

 their pedicels and inserted between the older tlowers. so that, as a matter of coui-se. 

 their stigmas are brushed by the pollen of the older flowers, if it does not indeed fall 

 <»i thenu 



The geitonog-;imy in the Bistort {Polygonum Biftcr-U} ^ is very strauiire. It is 

 rendered rather complex, as a pecnliar distribution of the sexes is combined with a 

 prcmounoed dichog;vmy and a pecnliar way of opening. The inl3orescence. which 

 looks like a spike, is really composed of numbei-s of tiny two-flowered groups 

 erewded together. One of the two dowers of each little group is long-styled and 

 Tjiily hermaphi\xlit*, while the other contains a short style, well-formed stamens. 

 and a rudimentary ovary which develops no further. It is therefore a pisendo- 

 hennaphrodite statninate flower. In each gi>o\ip the long-styled hei-maphi>xlite 

 flovrer opens iirst. beginning at the base of the apparent spike and gradually 

 woiking tip to the top. The staminate riowers do not get their turn until the 

 highest of the long-styled flowers has opened: but after this they behave exactly 

 like their neighbours, i>, the lowest develops tirst The long-styled flowers are pro- 

 teuadrwas. At the commencement of flowering the pollen-covei-ed anthei-s project 

 a millimetre from the perianth: the styles, however, are still short and hidden iu the 

 interior. At this time pollen can only be removed from the flowers. Then the 

 .withers fall off and the styles elongt^te so as to protrude some 8 mm. beyond the 

 perianth. The whole spike is at this stage beset with receptive stigmas which can 

 ooh- he fertili.?ed by insects with pollen from other plants. But this state of thing-s 

 does not last loni:. for now the staminate iiowei-s open one after another in quick 

 stiecession. Their anthers, containing abtmdance of pollen, protrade 3 mm. beyond 

 thepoianth and come into contact with the still receptive stigmas of their neigh- 

 bciurs. s,~ that ireitonogamy results;. As soon as this is eltected the statninate flowei-s 

 beocsne detached from the a^iis of the spike and fall to the ground. . This geitono- 

 gsmy is of course tiseless to the stigmas which have already received pollen from 

 other plants by insect airencv, hut it is of the ^a-eatest import«ance to the flowers 



