| | 1. Stamens opposite petals |
| M. pentandra |
| | 1' Stamens alternate petals |
| |
| | 2. Cauline leaves 1–3; inflorescence blooming top to bottom |
| M. caulescens |
| | 2' Cauline leaves generally 0 (sometimes 1); inflorescence blooming bottom to top |
| |
| | 3. Petal lobes generally 5 or more, pinnate; styles each 2-lobed at tip; hypanthium wider than long, bell- or saucer-shaped |
| |
| | 4. Leaf blade ± round, 3–8 cm wide, lobes indistinct, 7–11, teeth ± round; pedicel generally > 1.5 mm; petiole glabrous to ± hairy; montane, > 1500 m |
| M. breweri |
| | 4' Leaf blade ovate-elliptic, generally < 4 cm wide, lobes distinct, ± 5, teeth ± sharp; pedicel generally < 1.5 mm; petiole densely hairy; ± coastal n California, < 1000 m |
| M. ovalis |
| | 3' Petal lobes 3, ± palmate at lobe tip; styles unlobed; hypanthium longer than wide, cup-shaped |
| |
| | 5. Leaf blade ovate, lobes ± deep, generally ± entire; petal lobes narrowly triangular; sometimes 1 leaf cauline |
| M. diversifolia |
| | 5' Leaf blade ± round, lobes ± shallow, teeth generally round; petal lobes ± elliptic; leaves basal |
| M. trifida
|