Scott, D. H., 1909. Studies in Fossil Botany, 2nd Edn. London, A. & C. Black Ltd. —— 1920. Studies in Fossil Botany, 3rd. Edn., vol. 1. London, A. & C. Black Ltd. —— 1923. Ibid., vol. 2. Wardlaw, C. W., 1944a. Experimental Observations on the Relation between Leaf Development and Stelar Morphology in Species of Dryopteris. Nature, 153, 377. —— 1944b. Bud Regeneration at Cut ParenchyAmatous Surfaces in Onocleoid Ferns. Nature, 153, 588. —— 1945. An Experimental Treatment of the Apical Meristem in Ferns. Nature, 156, 39. Zimmermann, W., 1930. Phylogenie der Pflanzen. Jena, Gustav Fischer. (Quoted from Bower, 1935, ch. 30.) P.S.—Recent work by Wardlaw (see above) would modify the figure given here for the fern apex, by a small-celled tissue (meristematic) stretching across from the ends of the procambia to form a concave zone below the apical cell. This may not be universal among the ferns.—I. V. N., June, 1948.

Evolution Of the Alien Flora of New Zealand. By A. J. Healy, Department S.I.R., Wellington. The alien flora may be defined as that group of non-native plants (in this paper confined to Dicotyledones, Monocotyledones, Gymnospermae and Pteridophyta) that exist in the non-cultivated state in New Zealand. The documented history of the evolution of the alien flora of New Zealand commences in 1788 with the publication of Forster's Florulae Insularum Australium Prodromus, wherein is recorded the first alien species—canary grass (Phalaris canariensis), giving a definite evolutionary period of 160 years. It is possible that the initial stage of the evolution commenced about 1150 A.D. with the arrival of Toi, the first of the Maori voyagers, and continued through the pre-pakeha period to 1769, the arrival time of Cook's first expedition. The taro, paper mulberry, etc., were intentionally introduced during that period, and it seems feasible to suggest that such cosmopolitan species as Oxalis corniculata, Calystegia septum, Solanum nigrum, and Sonchus sp. came in as “stowaways,” perhaps in the soil about the roots of the useful plants; some of these species were collected by Banks and Solander, and had every appearance of aboriginal species. Two essential factors for the development of an alien flora are that there exists the necessary commercial intercourse between the particular region under consideration and other countries by which seeds can be introduced, and that a suitable environment is present for the establishment of the species so introduced. In the case of New Zealand, contact with overseas was initiated by the English and French expeditions which came at the beginning of the pakeha period, and was continued by the increasing advent of whalers, sealers and timber seekers who established bases in New Zealand. Samuel Marsden introduced farm livestock and initiated general agricultural activities in 1814, and was followed by other missionaries and the establishment of more missionary stations, and by 1840 considerable overseas trade was taking place, and the Bay of Islands had become a commercial centre. After 1840, active colonization was the order of the day, and the area under settlement was increasing rapidly every year; large tracts of tussock grassland were taken up for pastoral purposes and were being sown with English grasses; land was being felled and/or burned out of forest and seed was sown on the ash. This widespread sowing of imported grass-seed mixtures with high content of extraneous seeds up to the time when local supplies of relatively high purity were available was responsible for the introduction, of a large number of aliens, and for their widespread dispersal. The imported seed of many agricultural crops accounted for more introductions and has even been operative in recent years.