| 1 | Perennial with a thick woody rootstock; leaf-segments prominently reticulate-nerved below; fruit c. 4 mm long |
| 1' | Annuals or biennials, without a thick woody rootstock; fruit up to c. 3 mm long |
| 2 | Basal leaves usually withered at anthesis ; plants biennial, 50-100 cm high; umbels 12-60-rayed, usually drooping immediately before anthesis; fruits hispid with spreading bristles |
| 2' | Basal leaves usually present at anthesis, commonly undivided, suborbicular or labelliform; plants annual, 5-70 cm high; umbels 4-20-rayed, usually erect immediately before anthesis; fruits puberulous |
| 3 | Basal leaves coarsely and irregularly toothed; fruit pyriform, c. 3 mm long; umbels 10-20-rayed; petals not or obscurely radiant |
| 3' | Basal leaves crenate or bluntly crenate-dentate; fruit ovoid, c. 1.8 mm long; umbels 4-12-rayed; outer petals distinctly radiant |
