Distribution patterns of plants associated with arable field edges.
Distribution records of the flora within arable field boundaries and the associated crop indicated that most species in field boundaries did not occur in the crop area. About 30% of the species recorded in the boundary were found also at varying distances into the crop. Many of these were found only within 2.5 m of the undisturbed field edge, though some important field weeds appeared to originate in the margins, including Bromus sterilis, Elymus repens and Galium aparine. Four types of plant distribution were found on 2 farms, one in Cambridgeshire and the other in Hampshire. Plants were (i) limited to the margin, (ii) limited to the crop but occasionally found in the hedge-bottom, (iii) occurred at the boundary and at decreasing density into the crop, or (iv) distributed through the headland with highest densities between 1 and 5 m from the field edge. A number of annual arable weeds including Veronica persica were recorded at low densities within the field boundary and were present in the boundary seed bank. The distribution of the viable buried seed flora from soil samples taken at different distances from the field boundary were similar to those of the plants above ground.