THE COMMON ARUM 



carpel, without any other floral parts. Above 

 these groups of simple male and female flowers 

 we find some other b6dies shaped hke the lower 

 female flowers, but from their surfaces appear long 

 bristles which stand out from the axis and point 

 downwards. These objects are really abortive 

 female flowers modified to serve another purpose 

 in the plant's economy — and of these more will be 

 said later. 



Now that we understand the various parts w^hich 

 constitute the quaint floral structure of the arum, 

 we may proceed to see what connection they 

 have with the tiny midges that so love to visit 

 them. 



The purple club is the sign-post that attracts 

 the midges, for it is, of course, quite a conspicuous 

 object as it stands against the pale green hood that 

 envelops it. So presently the arum-seeking flies 

 come along and espy the familiar sign-post. Not 

 a moment is lost. They steer quickly for it, alight 

 upon it, and gleefully descend until they reach the 

 narrow neck portion, where they meet the bristly 

 abortive flowers. These latter, with their bristles 

 pointing downwards, prove no obstacle to the 

 midges so they travel down to the base of the 

 flower. 



Many of the insects have just come from other 

 arum blooms in the near neighbourhood, and 

 about their wings, legs, and bodies they carry 

 traces of their previous feastings, in the form of 

 minute pollen grains. When, though, they reach 

 an arum at about the stage of that shown in 



39 



