| 1. Heads discoid (or rays rarely 13) |
| W. invenusta |
| 1' Heads radiate, rays 521+ |
| |
| 2. Basal leaves 0 at flowering (or generally < cauline leaves) |
| |
| 3. Outer phyllaries many, generally < 6 mm wide; involucre hemispheric; plants generally > 50 cm |
| |
| 4. Plant densely soft-hairy; fruit 1012 mm, glabrous or short-hairy above; pappus 13 mm |
| W. elata |
| 4' Plant scabrous and sparsely bristly; fruit 56 mm; pappus 0 or minute |
| W. reticulata |
| 3' Outer phyllaries few, leaf-like, generally 617 mm wide; involucre bell-shaped; plants 1030 cm |
| |
| 5. Head 1; leaves glabrous; pappus 0 |
| W. bolanderi |
| 5' Heads generally several; young leaves tomentose; pappus a crown of low triangular scales |
| W. ovata |
| 2' Basal leaves present at flowering, generally > cauline leaves |
| |
| 6. Outer phyllaries wide, leaf-like, generally >> inner; head generally 1, large |
| |
| 7. Plant shiny green, glabrous to sparsely short-hairy, glandular; phyllaries glabrous or glandular; fruit 1012 mm |
| W. glabra |
| 7' Plant densely tomentose, becoming glabrous; phyllaries persistently tomentose; fruit 1215 mm |
| W. helenioides |
| 6' Outer phyllaries narrow, generally barely > inner; heads 1few |
| |
| 8. Plants ± tomentose, becoming glabrous; phyllaries generally few |
| W. mollis |
| 8' Plants short-hairy; phyllaries generally many |
| |
| 9. Phyllaries ± soft-hairy, ciliate; head generally 1 |
| W. angustifolia |
| 9' Phyllaries puberulent, not ciliate; heads 14 |
| W. longicaulis
|