WIND POLLINATION 309 



negligible or non-existent. In fact, they may do more 

 harm than good by causing pollen to be scattered at 

 inopportune moments. Among the catkinate plants, 

 which are generally anemophilous, the Willows are ex- 

 ceptional. They are pollinated by insects .-'''^he Com- 

 mon Sallow, or Goat WiUow {Salix caprea) produces 

 upright catkins, which in Britain are collected by 

 children for use on Palm Sunday, and called " palms." 

 The sexes are represented on separate trees, the short, 

 thick male catkins being particularly conspicuous on 

 account of the bright yellow anthers. The pollen is 

 sticky, and is sought by bees on its own account, but 

 there is the additional attraction of honey secreted by 

 small scales at the base of each flower. This lures 

 moths as well as bees to the service of the species. The 

 flowers appear before leaves are developed — a very sig- 

 niflcant feature, seeming to indicate a transition from 

 wind to insect pollination. It is probable that in the 

 evolution of flowers wind pollination came before insect 

 pollination. It may be that in Salix caprea we have a 

 living example of a stage in the advance from anemo- 

 philly, but there are also plants which are now anemo- 

 philous that have clearly descended from insect-pollin- 

 ated ancestors. The evidence for descent is found in 

 vestiges of the more glorious days of the " good old 

 times." The Docks (Rumex), although wind pollinated, 

 stiU secrete a little honey. The small Meadow-Eue 

 {Thalictrum minus) exhibits traces of what in its remote 

 ancestors must have been showy and attractive corollas, 

 and the Salad Burnet {Poterium sanguisorba) , a member 

 of the Rose family foimd in limestone districts, secretes 

 a little honey, and its pollen is sticky. 



