2. “On some Naturalized Plants of Otago,” by G. M. Thomson.
Dr. Berggren, of the University of Lund, said that, although he had only been a short time in New Zealand, he was astonished to see how many introduced plants had spread and become naturalized, as it was so different from what he had been accustomed to in Europe. He had no doubt that
Mr. G. M. Thomson's list would soon be doubled; but some of the plants on that list he thought should be considered as New Zealand plants, such as Polygonum aviculare and Sonchus oleraceus. He had noticed in and near the rivers in Canterbury Nasturtium amphibium and Anacharis alsinastrum; these plants spread from America and Southern Europe into Northern Europe in exactly the same way. Most of these plants, he thought, would continue; and even the injurious ones would be more difficult to keep down by cultivation than they were in Europe, on account of good climate. With reference to the appearance and disappearance of thistles, he remarked that in Sweden, when the forest is cut down and burnt, Geranium bohemicum appears, no one knows whence; but in a few years it disappears, and never comes again. In the same way, when land is first broken up for cultivation, it comes, but soon goes again.