| | 1. Leaf glabrous or ± hairy; filaments all densely purple-hairy; fruit glabrous to glandular-puberulent |
| |
| | 2. Leaf glabrous; lower pedicels 10–15(25) mm, 1 per node |
| V. blattaria |
| | 2' Leaf ± hairy; lower pedicels < 10 mm, 1–4 per node |
| V. virgatum |
| | 1' Leaf densely woolly-tomentose; upper 3 filaments white- or yellow-hairy, lower 2 glabrous to ± hairy; fruit densely tomentose |
| |
| | 3. Leaf not decurrent; inflorescence openly branched |
| V. speciosum |
| | 3' Leaf decurrent; inflorescence dense, generally unbranched |
| V. thapsus
|