Smith. — Plants naturalised in the County of Ashhurton. 207 



From numerous inquiries instituted among the early 

 settlers I have ascertained that every crop they sowed, be 

 it cereal or fodder, new plants appeared on cheir farms. Some 

 species would gi'ow vigorously for a few years, and in a few 

 more years they would decrease and disappear. It is gene- 

 rally difficult or impossible, from the vague descriptions the 

 old settlers give of these plants, to identify them accurately. 

 But probably they remained so long as the rich virgin soil 

 retained certain plant-food necessary to sustain them, and 

 when the land became impoverished by repeated and un- 

 scrupulous cropping without restoring the exhausted elements 

 of the soil they were replaced by more vigorous species better 

 adapted to the changed conditions. Nine years ago Scandix 

 pecten-veneris was very abundant and intrusive, and covered 

 acres of good land in some localities ; but it is now compara- 

 tively rare. Many other species of exotic plants have also 

 become less numerous within the same period. Warm sea- 

 sons or continuous periods of dry, warm weather are more 

 favourable to the development of some introduced plants than 

 to others. During the drought and hot weather experienced 

 on the Canterbury Plains in the years 1895-97 Solanum ni- 

 grum, Datura stramonium, and Atropa belladonna became very 

 abundant and aggressive on rich swampy lands and along the 

 banks of water-races in several districts in the county. These 

 dry years were succeeded by a wet and chilly period lasting to 

 the present time, and these plants have consequently become 

 rare. It would have been regrettable if these heat-loving but 

 dangerous plants had become numerous in this extensive 

 farming district. My observations on many species of natural- 

 ised plants during the last fifteen years has convinced me 

 that their comparative habits in all seasons is a safe guide in 

 tracing the source of their original home. 



It may be of interest to botanists of the future to give brief 

 notes on the condition of the naturalised flora of the county 

 at the beginning of the twentieth century. Of the 368 species 

 included in the following list — specimens of all having been 

 collected in the county — 95 per cent, belong to the Scandi- 

 navian flora; Australia is represented by 3 species. North 

 Africa 1, South Africa 1, Asia 3, South America 3, and North 

 America by 10 species. 



The three Australian species are well dispersed over the 

 hilly region of the county. Vittadinia australis and AccBJia 

 ovma are abundant on the hills and in the warmer inland 

 valleys. The latter grows vigorously, and is becoming a great 

 nuisance to sheep-owners by its burrs or seed-pods entangling 

 in the wool. Cotula australis inhabits the warm valleys of the 

 Gawler Downs, on the upper Hinds Kiver. 



The North African Gytisus albidus constituted for a de- 



