European cardoon which broke out of some garden on the banks of the River 

 Plate, acquired a gigantic structure, and rapidly spread, in impenetrable 

 thickets, over thousands of square miles of the Pampas. The Anicharis 

 alsinastrum, a water plant not much inclined to spread in its native American 

 habitat, has found its way into English rivers, and in some instances has not 

 only greatly retarded their currents, but has formed a serious impediment to 

 navigation. The water-ci*ess introduced into the River Avon, in Christchurch, 

 has spread to such an extent as to obstruct the flow of the river and greatly to 

 raise its natui'al level, evils only counteracted by the annual expenditure of 

 large sums of money. The Scotch thistle is spreading over both islands, and 

 has already entailed ujoon the farmer and the squatter a serioiis addition to his 

 expenses. 



So far as New Zealand is concerned, there can be no doubt that what is 

 taking place miisfc be at the expense of the native flora, and must, even alone, 

 have sooner or later led to the extirpation of many of the native plants. 

 But when, in aid of these operations, we find the whole country roamed over 

 by man himself, and by countless herds of animals which he has introduced, we 

 may feel assured that the native life has but little chance against the invaders. 

 Wherever we fire the forest or cut a track, we make room for the invader, and 

 where the hardy European vegetable once begins to grow it usually retains its 

 hold. I noticed recently, at sub-alpine elevations in the Middle Island, that 

 Trifolium pratense was gradually displacing native herbaceous vegetation, a 

 process the more certain in proportion to the treading which the soil I'eceives 

 from cattle and sheep. But, perhaps, one of the most noticeable facts is, that 

 along our lines of highway, especially in the Canterbury Province, you scarcely 

 see, for miles together, a single native plant in the hedge rows or fences, whilst 

 the familiar wayside weeds of Europe are found as abundantly as they are in 

 the mother country. 



The author concluded his lecture by observing (in the words of an eloquent 

 author), " that the mysterious but undeniable movements which he had 

 attempted to elucidate were ever going on, progressing on a grand and imposing 

 scale, and altering the vegetable chai-acter of the whole coimtry, showing, in 

 indelible signs, the silent but ii'resistible force with which humble plants may 

 prescribe a path to man, and that strange relation between them which makes 

 plants of equal importance to his existence and to his welfare." 



The author then apologized for not having extended his lecture to the case 

 of the fauna as well as that of the floi-a, but pleaded his pressing engagements 

 as his excuse. He, however, expressed a hope that on some future occasion 

 he should be able to deal with the subject. 



