Arable weeds
Arable farming refers to the growing of annual crops such as potatos, turnips, oil-seed rape, barley, wheat, oats, maize, rye, flax etc. Arable farming makes up a much smaller portion of northern Ireland agriculture today than a century ago, having been largely supplanted by permanent grass for grazing, hay or silage.
Associated with arable fields are certain characteristic weed species, some of which were once quite abundant, but are now very rare or even practically extinct. Examples are:
| Corncockle | Agrostemma githago | practically extinct |
| Cornflower | Centaurea cyanus | practically extinct |
| Gold-of-pleasure | Camelina sativa | practically extinct |
| Shepherd's needle | Scandix pecten-veneris | practically extinct |
| Fool's parsley | Aethusa cynapium | practically extinct |
| Redshank | Persicaria maculosa | common |
| Fumitory | Fumaria spp. | common |
| Corn poppy | Papaver dubium | frequent |
| Shepherd's purse | Capsella bursa-pastoris | common |
| Pineapple weed | Matricaria discoidea | common |
| Black bindweed | Fallopia convolvulus | frequent |
| Corn marigold | Chrysanthemum segetum | frequent |