Botanical Aspects of Hay Fever in Wellington.

By Doris W. Filmer and W. F. Harris, Botany Division, D.S.I.R., Wellington.

During the hay-fever seasons 1945–6, 1946–7, investigations were made in Wellington of the occurrence, distribution and flowering seasons of known hay fever and anemophilous plants; and atmospheric pollens were studied by the examination of specially prepared microscope slides exposed at three stations. At two of these stations new devices were employed for the exposure of slides by both the gravity and impact methods. Pollen counts were consistently higher on the slides exposed by the impact method, so these gave a better idea of the species of pollen in the air and their relative abundance. The atmospheric surveys showed which species of plants shed large quantities of buoyant pollen, and the relative abundance of their pollens in the air; and also indicated, by the recorded duration of the pollen showers, the flowering seasons of the different species.

Plants which are abundant and produce large quantities of buoyant, allergenic pollens are the principal factors in the hay-fever season. The correlation of the results obtained by the field studies and the atmospheric surveys showed which are the most important causes of hay fever in Wellington. Of those listed below, the grasses are the most important.