THE CANADIAN HORTICTJLTtJRIST. 



257 



THISTLES. 



(From Colin Clout's Diary J. 



Nature, indeed, has been very prodi- 

 j^al to thistles ; she has given them 

 every advantage and no enemies on 

 earth, except farmers and donkeys. 

 Just look at such a head as this that I 

 have cut off clean with a switch of my 

 stick, and then consider what fraction 

 of a chance the wheat or the wheat-grow- 

 ers have got against it. Each stalk sup- 

 ports some dozen heads of blossom at 

 least, and each head contains a hundred 

 separate flowers, every one of them 

 destined to produce in due time a winged 

 and tufted seed. The thistles are mem- 

 bers of the great composite family, like 

 daisies and the dandelions, and tliey 

 have their little bells clustered together 

 after the common composite fashion 

 into close and compact flower-heads. If 

 you cutthehead through with your knife, 

 longitudinally — it is diflicult to tear it 

 open because of the prickly tips of the 

 bi-acts — you will see that it is made 

 up of innumerable distinct pur|)le 

 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 

 thistle down), which are in fact the 

 altered and modified relics of original 

 calyx. Even in its simplest form, the 

 composite flower bears the 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 per- 

 sistent and noxious an enemy to us 

 agricidturists. It is one of the most 

 higlily evolved and successful of living 

 jtlants ; and it pits itself against the 

 relatively simi)le and sickly wheat, an 

 artificial jjlant with a feeble constitu- 

 tion, which we ourselves have sedu- 

 lously 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 decade ; as Euro- 

 pean 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 

 fuither back in its history than that, 

 was already a very advanced sort of 

 plant, with a number of little tubular 

 blossoms, like miniature Canterbury 

 bells, crowded together comj^actly into 

 clustered many-flowex-ed heads. The 

 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 sev- 

 erally descended the daisies, the dande- 

 lions 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 producing 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 of the 

 daisies, and colored them uniformly 

 yellow throughout, on behalf of the 

 little yellow-loving flies by whom its 

 seeds are usually fertilized. But the 

 thistles, the central tribe of all, re- 

 tained more sim})ly the original habits 

 of the race, in that all their florets are 

 still tubular, instead of being split out 

 into sti'ap-shaped rays ; while the vast 

 majority of them keep as yet to the 

 primitive purple tinctures of their 

 race, which endear them to the higher 

 insects. Bees are the chief fertilizei'S 

 of thistle-heads ; but butterflies also 

 frequently pay them a visit, and in the 

 home-close at the present moment they 

 are being attended b) :liousands of 



