350 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



seen in the tendency of mignonette and annual stocks to become biennial and 

 some perennial, in the indigenous form of Cardamine hirsuta being 

 perennial, and in the fact that many weeds that seed but once with us, 

 seed during a greater part of the year in New Zealand. 



Another cause must be sought in the fact that more of their seeds 

 escape the ravages of birds and insects in New Zealand than in England, 

 the granivorous birds and insects that follow cultivation not having been 

 transported to the Antipodes with the weeds, or, at least, not in propor- 

 tionate numbers. 



" Still the fact remains as yet unaccounted for, that annual weeds, 

 which, except for the interference of man, would with us have no chance 

 in the struggle with perennials, in New Zealand have spread in incon- 

 ceivable quantities into the wildest glens, long before either white men 

 or even their cattle and flocks penetrate their recesses." * 



The latest instance recorded of a similar destruction by an intruder is 

 the following extract from the " Daily Telegraph " (1909) : — " Great mis- 

 chief is being wrought in Queensland by the prickly pear. In his recent 

 tour in the country to the north-west of Brisbane, the Minister for Lands 

 was appealed to by new settlers to defer payments during the early years 

 of settlement, as they have to wage a strenuous fight against the pest. 

 Mr. Denhani states that there are men in the Taroom district who 

 remember when the only clump of pear in the countryside was in a 

 garden at Eockdale. To-day there are thousands of acres of the plant, 

 and in some places roads are so hemmed in as to make the crossing of 

 vehicles difficult. The Minister severely condemns lessees who have, by 

 their indifference, practically watched the ruin of their holdings. A few 

 early steps would have saved thousands of acres now lost to cultivation. 

 Loose views on the part of settlers in regard to their responsibilities as 

 Crown tenants, and the holding of too much country, are conditions 

 which have favoured the pear's spread. Mr, Denham is of opinion that 

 closer settlement is now the only remedy, but this is impossible without 

 railway communication. Unless something is done speedily, large areas 

 of fertile country will be lost to the State. 



Of foreign plants more or less widely distributed over the British 

 Isles the following may be mentioned : — 



Lepidium Draba (Whitlow Pepper- Wort). — This is said to be abun- 

 dant in the Caspian region. I have found it in Malta, and it is believed 

 to have been introduced after the unfortunate Walcheren expedition in 

 1809, when Lord Chatham landed at Yeere and took Middelburg and 

 Flushing, but had to retire, having lost 7,000 men by fever. It has now 

 spread over the south and midland counties. 



Sencbiera didyma.—A. native of temperate South America. Hooker 

 says of it, " Waste ground from Fife southwards ; S. and W. Ireland." 

 It has of late years become very abundant in the Channel Islands. 



Galinsoga parviflora. — A native of Central and S. America, first 

 noticed in Europe about a century ago ; but is now abundant, especially 

 in Surrey and Middlesex. 



Erigcron canadcnsc.—- u This N. American plant has spread over all 



* " On the Struggle for Existence amongst Plants," Popular Science Review, 

 vol. vi. p. 138. 



