AUTOGAMY BY MOVEMENTS OF STAMENS. 



34a 



namely, pseudo- hermaphrodite (c/. p. 294) male flowers (fig. 296 1) and true her- 

 maphrodite flowers (figs. 296 2-3.*). The latter open earlier than the former, 

 which, indeed, never come into play until the hermaphrodite flowers have cast 

 both stamens and petals. Directly the petals open in the hermaphrodite flowers 

 a finely-granulated honey-secreting disc and two short styles are revealed in the 

 middle of the flower. The stigmas at the extremities of the styles are already 

 mature, but the stamens are incurved like hooks and have their anthers still closed 

 (fig. 296 2). The day after, also, when the petals have opened further back and 



Fig. 297.— Autogamy effected by inclination of curved stamens. 



' drccea alpina. 2 a nen-ly-opened flower of Circcm alpina wiih the front petal removed. », * The same flower at a later stage 

 of development, s Fruit of Circcea alpina. « Agrvmonia Eupatoria. ^, 8, s, *" Successive phases of a flower of Agrinwnia 

 Eupatoria^ which is at first adapted to heterogamy (cross-pollination) and subsequently to autogamy, u Young fruit of 

 AgrvmoTua Eupatoria. ^, ^, ^^ natural size ; the rest of the figures magnified. 



the filaments have straightened out (fig. 296 ^), the anthers surrounding the stigma 

 in a circle are still closed, so that pollination can only take place at this period in 

 the event of insects bringing pollen from other flowers. The anthers and filaments 

 have, however, now entered upon an active phase. The curved stamens bend 

 successively at short intervals, one after the other (after one has started, the next 

 to follow is the stamen next but one to the left, and so on till all have done) 

 towards the centre of the flower, bringing their anthers, which have meanwhile 

 undergone dehiscence and are covered with pollen, into contact with the stigmas 

 precisely in the manner shown in flg. 296 *. Each stamen only stays a short time 

 in this position, and then executes a backward movement and makes way for the 

 next in order. When all the stamens have accomplished these evolutions, they as 

 well as the petals become detached and fall to the ground. The secretion of honey 



