THISTLEDOWN BLOWS. 149 



gather compactly into a clustered many-flowered head. 

 Its petals were probably purple, and its calyx had even 

 then assumed the form of long floating hairs to the ripe 

 seed. But at an early stage of their life as composites, the 

 group broke up into three minor tribes, from which are 

 severally descended the daisies, the dandelions, and the 

 thistles ; for under one or other of those general heads 

 the many thousand known species may be roughly 

 classified. The daisy tribe, as we all know, took to pro- 

 ducing mostly yellow florets, with white or pink outer 

 rays, to allure their special insect allies. The dandelion 

 tribe turned all its florets throughout the entire head 

 into long rays, like the external row in the daisies, and 

 coloured them uniformly yellow throughout, on behalf 

 of the little yellow-loving flies by whom its seeds are 

 usually fertilised. But the thistles, the central tribe of 

 all, retained more simply the original habits of the race, 

 in that all their florets are still tubular, instead of being 

 split out into strap-shaped rays ; while the vast majority 

 of them keep as yet to the primitive purple tinctures of 

 their race, which specially endear them to the higher 

 insects. Bees are the chief fertilisers of thistle-heads ; 

 but butterflies also frequently pay them a visit ; and in 

 the Home Close at the present moment they are being 

 attended by thousands of little black and red burnet 

 moths, which prefer the long bell-shaped blossoms even 

 to that favourite flower with them, the bird's-foot trefoil. 

 Almost every head in the field is covered by half a 

 dozen moths at once, all drinking nectar from the re- 

 cesses of the deep long tube, and all unconsciously 

 carrying pollen from stem to stem on their uncoiled 

 proboscis. 



