BUTTERCUP EVOLUTION 



degeneration. When flowers begin to lose their 

 petals there is always the danger of their de- 

 generating into habits of wind-fertilisation. In- 

 deed, there is some considerable reason for think- 

 ing that even now the clematis is developing that 

 habit ; while the Meadow Rues (Thalictrum), in 

 some of their species, already depend upon the 

 wind as their pollen-carrier. 



The meadow rues have, like the anemone and 

 the marsh marigold, lost their petals and nectaries, 

 but they have gone farther than this ; their sepals 

 have dwindled into greenish scales which are now 

 only tinted with the pink and yellow colours they 

 once possessed. In the Lesser Meadow Rue 

 (Thalictricm minus) the flowers are arranged in a 

 loose panicle, and each one is suspended on a 

 slender stalk, so that the wind can readily shake 

 its pollen from the long stamens that project 

 beyond the calyx ; indeed, the whole floral 

 arrangement has become well adapted to the 

 requirements of wind-fertilisation. 



In some of the Meadow Rue species the 

 stamens have become large and showy, like those 

 of the willow catkins previously considered, and in 

 this way insects are attracted to their pollen. 

 Also, as if to assist this purpose, when at the 

 height of their showiness the sepals are thrown 

 completely off, whereby the coloured filaments of 

 the stamens are exposed. The familiar Columbine- 

 leaved Meadow Rue ( Thalictriim aqidlegifoliiim) 

 shown in Fig. 105 (Plate '](y)y and common in 

 country gardens, exhibits these features. Thus 



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