| 1. Petal generally < 3 mm, ± = calyx lobe; stipules inconspicuous |
| B. rotundifolia |
| 1' Petal > 3 mm, >> calyx lobe; stipules obvious |
| |
| 2. Stipule ± 1 cm or more, generally toothed; inflorescence dense; petal generally > 5 mm |
| B. major |
| 2' Stipule ± 24 mm, bristly; inflorescence open; petal generally < 5 mm |
| B. occidentalis
|