Some Records of the Seasonal Flora of Arable Land Under Cultivation

Abstract

For several years the writers have kept accurate records of the numerical and seasonal occurrence of the weeds of arable land under ordinary culture. The flora of any arable field is exceedingly scanty both as regards number and species, rarely more than 30-35 species commonly occurring on a farm lying over a single geological outcrop, that is, with only one fairly uniform type of soil. Special clay, sand, loam or chalk plant-associations develop according to the character of the soil, and by reason of the agricultural operations carried out through the year these associations are composed almost entirely of annuals, with seedlings and young plants of those perennials which have wind-borne fruits capable of rapid germination; such species form the first vegetation on waste land when abandoned by the farmer. The frequency of occurrence of arable land weeds and the flora types met with on different geological horizons have been worked out by Dr Winifred Brenchley1 who, however, only observed the relative frequency of summer flowering plants in growing crops without reference to their actual number and seasonal distribution. Plant counts of old pastures have been carefully made by S. F. Armstrong2 and others, but again only for special areas and in the summer. Seasonal records of arable land plants have also been recorded for certain western pastures and arable by R. G. Stapledon3 who counted the plants in several small areas (one sq. foot) at intervals throughout the year, the squares being selected haphazard from different parts of the same field and the counts added together. None of these methods, however, gives an idea of the number of plants surviving ordinary agricultural operations on arable land throughout the season, and the authors therefore arranged an experiment to determine the succession of plants on one plot of land over an entire year. Their method was as follows: A square wooden frame with an inside area of one yard was thrown down in a field at a fixed distance (two chains) from the headlands. The exact site was noted by measuring coordinates to pegs fixed in the hedgerows at right angles to the sides of the frame. Pegs were thrust down nearly flush with the ground at each corner and left there when the frame was lifted up so that it could be easily slipped back on the same place at the subsequent visits. The