40 REPORT — 1860. 



flowering head in the following season, which would thus give us the following 

 sum as the seeding capabilities of a single Thistle plant, namely — 



150 x 10 X 8= 12000. 

 These figures then will account for the " Plague of Thistles " which one 

 sometimes hears of, and points out most forcibly the importance of not 

 allowing these plants to perfect their seed, and hence waste places and 

 neglected waysides should carefully be watched in this respect ; but as this 

 cannot adequately be done without compulsory enactments, it is interesting 

 to find that some of our colonies have already instituted state laws with 

 reference to this subject, and during the last Session of Parliament an attempt 

 was made to get an act applicable for this object for Ireland. The destroying 

 of such thickets of Thistles as we have described has ever been an object of 

 interest with the farmer ; and it is not a little curious to remark that the 

 operations connected therewith have so much been regulated by rhyming 

 directions, as follows : — 



" Thistles cut in April, 



Come up in a little while ; 



If in May, 



They grow the next day; 



If in June, 



They '11 grow again soon ; 



If in July, 



They '11 hardly die; 



If in August, 



Die they must." 



These words, uncouth as they are, are still meant to express some important 

 facts in the natural history of the plant. It may be observed that, with the 

 preparation we have described of underground buds, there can be no wonder 

 at the quick reappearance of the plant on early cutting ; at the same time, 

 if we consider that the whole of the aboveground parts of the plants 

 would naturally die at the first approach of cold, we may conclude that the 

 decree of 



" If cut in August, 

 Die they must " 



is more apparent than real. For while the tertiary buds are advancing to 

 flower, they are also active in providing a still newer growth of rhizomata and 

 buds to perpetuate the continuance of the plant; and hence we have no hesi- 

 tation in saying that never can this thistle be destroyed by late cutting off its 

 aboveground stems. However, even at this time much good may be done 

 in keeping down the reproduction of the plant; for by the August mowing 

 seeding is prevented, though even for this object we should prefer an earlier 

 cutting, as one head of flowers usually ripens at a time, and not all at once. 



Carduus acaulis. — We last year reported upon our experiments with the 

 true acauline form and the slightly cauline examples of this species ; we have 

 now to remark that the acauline examples maintain their normal condition, 

 whilst the cauline ones, from being only about 3 inches high when selected 

 for the experiment, have this year advanced to a complete thicket of stems 

 nearly a yard high, some of which have as many as a dozen heads of flowers, 

 and is a very showy and handsome plant. 



Carduus tuberosus. — The specimens originally discovered by us at Ave- 

 bury Druidical Circle have now advanced to immense masses, both as regards 

 their summer development of flowers and their tuberous rootstocks ; the 

 flowers are above 3 feet high, much branched and very showy, very different 

 from the single, or at most two-headed flower-stems of the ' English Flora,' 

 pi. 2562, which, however, is a faithful representation of the plant we trans- 

 ported to our garden. The tubers with us are as large as those of Dahlias. 



