THISTLEDOWN BLOWS. 141 



the prickly tips to the bracts you will see that it is 

 made up of innumerable distinct purple florets : each 

 with five petals united into a long deep tube, and each 

 with a little seed-like fruit at the bottom, crowned by a 

 ring of hairs (the future thistledown), which are in fact 

 the altered and modified relics of the original calyx. 

 Even in its simplest form, the composite flower bears 

 marks of being an extremely developed floral type ; and 

 the thistle, though relatively simple, is very far from 

 being the simplest among the composite plants. A 

 glance at the past history of the race will show why it 

 now proves so persistent and noxious an enemy to us 

 agriculturists. It is one of the most highly evolved and 

 successful of living plants ; and it pits itself against the 

 relatively simple and sickly wheat an artificial plant 

 with a feeble constitution, which we ourselves have sed- 

 ulously created for our own special use. The natural 

 consequence is that if we did not give every advantage 

 to the wheat and put every obstacle we can in the way 

 of the thistles, they would live it down in a single de- 

 cade ; as European weeds are living down the native 

 weeds of New Zealand, or as English vermin are living 

 down the aboriginal marsupials of isolated Australia. 



The primitive ancestral composite to go no further 

 back in its history than that was already a very ad- 

 vanced sort of plant, with a number of little tubular 

 blossoms, like miniature Canterbury bells, crowded 

 together 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 



