Arable fields: rye brome and swine's succory

Nowadays, arable fields tend to harbour few plant species. Numbers of arable weeds like rye brome and swine's succory have plummeted.

Trends

Fields used to harbour many weeds, but many of these have since become rare or have disappeared. Examples include orange lily, forking larkspur, corncockle, cornflower, corn marigold, rye brome and swine's succory.

This is illustrated by the figure, which shows the trend for the grass rye brome and the composite swine's succory. These two species used to occur in many of the 5 x 5 km grid squares before 1950, but nowadays rye brome is found in about 90 grid squares and swine's succory in only one.

The reasons why so many arable weeds have disappeared are that rye and oats have been replaced by maize, seed-cleaning and weed control (weedicides and mechanical treatments) have improved, more fertiliser is applied and fallow periods are shorter. Many weed species have disappeared because the crops they are associated with (flax, buckwheat, tobacco, hemp) are grown no longer, or only in small areas.

Many of the arable weeds are on the Red List of vascular plants. A plan has been issued to protect species of arable fields.