Table 1.
Wild relatives of Brassica napus in the UK. (Species are ranked in three ways: according to their ease of hybridization (Scheffler & Dale 1994); by the number of associated species with conservational status (Rodwell 1991; Cheffings & Farrell 2005); and by combining the above two to give an overall rank based on the capacity to inflict harm to species of conservational importance. This combined ranking was performed first on the basis of conservational importance (scarcity) of the recipient itself (although none of the species is scarce), second on the number of known associates with conservational status and third on ease of hybridization with the crop.)
| recipient species | hybridization rankinga | associate ranking | combined ranking |
|---|---|---|---|
| Brassica oleraceab | 3 | 1 | 1 |
| Diplotaxis muralisa | 7 | 2 | 2 |
| Raphanus raphanistruma | 6 | 3 | 3 |
| Sinapis arvensisa | 8 | 3 | 4 |
| Brassica nigrab | 5 | 4 | 5 |
| Brassica rapab | 1 | 5 | 6 |
| Brassica junceaa | 2 | 5 | 7 |
| Brassica carinataa | 4 | 5 | 8 |
| Diplotaxis erucoidesa | 7 | 5 | 9 |
| Sinapis albab | 8 | 5 | 10 |
| Brassica tournefortiia | 9 | 5 | 11 |
| Diplotaxis tenuifoliaa | 9 | 5 | 11 |
| Eruca vesicariaa | 9 | 5 | 11 |
| Raphanus sativusa | 9 | 5 | 11 |
| Erucastrum gallicumc | — | 5 | 12 |
| Hirschfeldia incanab | — | 5 | 12 |