PROCLAIMI.D PLANTS. I 85 



THF, PROCLAIMED PLANTS OF VICTORIA. 



7 he conditions by which a plant becomes a weed when 

 it leaves a restricted range and becomes disseminated over 

 wide areas by some unusually efficient agent for dissemina- 

 tion possesses much interest for the plant geographer. 



The opuntias can scarcely be said to be weeds in any 

 part of America, yet when taken to other countries propaga- 

 tion takes place so rapidly that much ground valuable for 

 agricultural purposes may be occupied. This appears to be 

 the case with the drooping prickly pear, Opitutia monacantha, 

 in the state of Victoria, Australia. Concerning it. Dr. A. J. 

 Ewart, the Government Botanist for that state, says in The 

 Journal of Agriculture of Victoria for June, 1908: 



"Every joint will strike root under favorable conditions, 

 and both the ripe and unripe fruits will do the same. The 

 joints may remain alive several months after cutting. They 

 can be destroyed by boiling, and may then be fed to stock 

 if care is taken to see that the spines, especially smaller ones, 

 have C(^me away. It is not, however, good food, being too 

 bulky and watery. Otherwise it can l)e buried in pits and 

 covered with soil, or piled in heaps and covered with quick 

 lime. In South Africa spraying with arsenite of soda is 

 recommended (2j/> to 4 per cent, solution), but this is costly 

 (probably £3 to £5 per acre in \'ictoria), and the plants 

 need to be burnt oft as soon as they have dried and before 

 new shoots appear. Spraying the standing plants with dilute 

 sulphuric acid in calm, dry weather is also fairly eftecti\'e but 

 less so than cutting. 



This plant appears to be increasing in Victoria, and 

 is spreading along the railways around the shores of Port 

 Phillip Bay, where it is likely to pro\e a great nuisance or 

 even danger if unchecked. The plant would without doubt 

 do great harm in the Mallee district if allowed to spread 

 there. Several other less common species grow in Australia, 



