134 



DICOTYLEDONS 



with several chambers, each representing one carpel 

 and containing one ovule attached to the axile placenta. 

 Style (sf) one, which divides above into as many branches 

 as there are carpels and ovary - chambers : each branch 

 of the style is stigmatic on its inner and upper surface. 



Fruit (fig. 164) a schizocarp 

 splitting into one-seeded cocci 

 (cc). Pollination. — In both 

 these species of Mallows the 

 stamensripen before the carpels, 

 and their opened anthers form 

 a group round the closed erect 

 style-branches. As the stigmas 

 ripen and commence to separ- 

 ate, the filaments gradually 

 bend backwards and outwards. 

 In M. sylvestris the anthers are 

 carried completely out of reach 

 of the stigmas, so that the 

 But in M. rotundifolia the 

 anthers are not borne so far backwards, whilst the style- 

 branches gradually curl over and bring the stigmas into contact 

 with the open anthers : thus the flower can regularly pollinate 

 itself. The flowers oi M. sylvestris axe more showy, and are 

 visited more frequently by insects which cause cross-pollination. 

 Thus we see that of these two flowers which are so much alike, 

 the more conspicuous is more frequently visited by insects, and 

 consequently more extensively cross-pollinated. This tends to 

 prove that conspicuousness of flowers aids in attracting insects. 

 On the other hand, the less conspicuous flower of M. rotun- 

 difolia is more often self-pollinated. This fact goes to show 

 that the more perfectly cross-pollination by insects is ensured, 

 the more precautions are taken to avert self-pollination; and 

 that, on the other hand, when cross-pollination is not ade- 

 quately secured, the flower makes provision for the formation 

 of seeds by self-pollination. Putting both results together, we 

 see that flowers are conspicuous in order to attract insects 

 which shall effect cross-pollination. 



Fig. 164. — Fruit of Malva sylvestris : 

 j/= sepals ; cc= cocci. 



flower cannot pollinate itself 



