AUTOGAMY BY A CO-OPERATION OF MOVEMENTS. 



385 



Allium Ghamoemoly (see fig. 311 ^) is an example of the plants, in whose flowers 

 autogamy is effected by concurrent movements of the pedicel and the style, the 

 former undergoing inflection, whilst the latter is inclined in the direction of the 

 spots where the pollen has been deposited. The small white flowers are lifted but 

 a very little way above the ground; at first they face the sky, and are half hidden 

 amongst the long green ribbon-shaped foliage-leaves. Nevertheless, they are 

 assiduously sought out by small insects, the honey, which is secreted in little depres- 

 sions on the surface of the ovary, being in great request. During the first stage of 

 flowering cross-pollination alone is possible; the stigma is posted in the middle of 



Fig. 310.— Autogamy resulting from an inflection of the pedicel accompanied by spiral torsion of the filaments: Cobcect 



scandens. 



1 Side view of a newly opened flower. 2, 3, 4 Flowers in the three successive stages of their development which lead to 



autogamy. All the figs, somewhat reduced. 



the mouth of the flower, and its tissue is already receptive whilst the anthers are 

 still closed and appressed to the walls of the perianth (see fig. 311 ^). Later on all 

 the filaments undergo inclination towards the middle of the flower; the anthers 

 burst open, become covered all over with the pollen which issues from their loculi, 

 and together form a yellow knob which occupies the centre of the entrance to the 

 interior of the flower, and is brushed by all intruding insects. The stigma is at that 

 stage hidden behind the anthers (see fig. 311 ^), and is not touched by insects. If, 

 for any reason whatever, insects do not visit a flower, autogamy takes place in the 

 third stage of its development. The pedicel curves over downwards and presses the 

 flower against the ground, and, as a consequence, the delicate white perianth-leaves 

 and filiform stamens are displaced, and some of the pollen falls out of the anthers 

 on to the lower perianth-leaves now resting upon the ground. The style undergoes 

 slight lateral, i.e. in these circumstances downward, inclination and the final result 

 of all these movements is that the stigma is brought into contact either with the 



Vol H. 



76 



