| | 1. Biennial or perennial herb (sometimes flowers 1st year); seeds lenticular and winged or fusiform and ribbed lengthwise |
| |
| | 2. Seeds ± fusiform, 3-ribbed lengthwise, not winged |
| M. torreyi |
| | 2' Seeds lenticular, winged |
| |
| | 3. Petal-like staminodes 5 |
| |
| | 4. Petal tips obtuse to rounded; sandy soils |
| M. multiflora subsp. longiloba |
| | 4' Petal tips acute; gypsum-clay soils |
| M. pterosperma |
| | 3' Petal-like staminodes 0 |
| |
| | 5. Petals > 30 mm; fruit generally > 25 mm |
| M. laevicaulis |
| | 5' Petals < 20 mm; fruit generally < 25 mm |
| |
| M. polita |
| | 6' Leaves toothed or lobed |
| |
| M. inyoensis |
| M. oreophila |
| | 1' Annual; seeds grain- or prism-like, or narrowed and folded near middle |
| |
| | 8. Fruit > 4 mm diam; seeds narrowed and folded near middle, end beak-like, ashy white; filament tip generally wide and minutely 2-toothed |
| |
| | 9. Petals 8, < 12 mm; filament tips acute, teeth 0 |
| M. reflexa |
| | 9' Petals 5, generally > 15 mm; filament tips 2-toothed, anther generally on thread-like stalk between teeth |
| |
| | 10. Flower bract white-scarious, margin green |
| M. involucrata |
| | 10' Flower bract green ± throughout (except sometimes base) |
| |
| | 11. Upper leaves and bracts ± cordate, clasping; fruit sessile, 14–25 mm, erect |
| M. hirsutissima |
| | 11' Upper leaves and bracts not clasping; fruit pedicelled, generally 9–15 mm, often reflexed |
| |
| | 12. Anther stalk generally < teeth; seeds narrowed at middle; e Sonoran Desert |
| M. tricuspis |
| | 12' Anther stalk generally > teeth; seeds narrowed above and below middle; c Mojave Desert |
| M. tridentata |
| | 8' Fruit generally < 4 mm diam; seeds grain- or prism-like; filament tip ± thread-like (except M. micrantha), not toothed |
| |
| | 13. Seeds 1-rowed above mid-ovary, prism-like, angles grooved |
| |
| | 14. Outer 5 filaments widened to 2-forked tip |
| M. micrantha |
| | 14' Outer filaments ± thread-like, tip not 2-forked |
| |
| | 15. Basal leaves lobed; sepals 2–7 mm; petals 3–10 mm; style 3–7 mm |
| M. affinis |
| | 15' Basal leaves entire or toothed; sepals 1–4 mm; petals 2–6 mm; style 1–3.5 mm |
| M. dispersa |
| | 13' Seeds 2–3-rowed above mid-ovary, grain-like, angles rounded or sharp, not grooved |
| |
| | 16. Flower bracts generally entire; axillary fruits often curved 90°+ |
| |
| | 17. Petals generally > 8 mm |
| |
| | 18. Seed not folded at 1 end, angles acute, surface pointed-papillate |
| M. jonesii |
| | 18' Seed with flap-like fold at 1 end, angles rounded, surface rounded-papillate |
| |
| | 19. Sepals > 8 mm; petals 12–24 mm; style 7–15 mm |
| M. eremophila |
| | 19' Sepals < 8 mm; petals 7–15 mm; style 4–8 mm |
| M. nitens |
| | 17' Petals generally < 8 mm |
| |
| M. desertorum |
| | 20' Seed surface papillate |
| |
| | 21. Seed angles acute, surface pointed-papillate |
| M. albicaulis |
| | 21' Seed angles rounded, surface rounded-papillate |
| M. obscura |
| | 16' Flower bracts toothed or lobed; axillary fruits straight, erect <|,"742"> |
| |
| | 22. Flower bracts green throughout, not whitish at base |
| |
| | 23. Petals 8–22 mm, tip obtuse to notched |
| M. pectinata |
| | 23' Petals > 20 mm, tip abruptly acuminate |
| |
| | 24. Petals 8–17 mm wide; c&s Sierra Nevada Foothills |
| M. crocea |
| | 24' Petals 16–33 mm wide; San Joaquin Valley, e San Francisco Bay Area, n Inner South Coast Ranges |
| M. lindleyi |
| | 22' Flower bracts whitish at base or ± white-scarious |
| |
| | 25. Flower bracts wide, ± concealing flowers and fruits, mostly white-scarious; inflorescence dense |
| M. congesta |
| | 25' Flowers bracts narrow, not concealing flowers and fruits, whitish below middle; inflorescence open to ± dense |
| |
| | 26. Petals generally > 8 mm |
| M. gracilenta |
| | 26' Petals generally < 8 mm |
| |
| | 27. Styles 1.5–3 mm; cauline leaves generally entire (or 2-lobed at base) |
| M. montana |
| | 27' Styles 3–6 mm; cauline leaves generally lobed |
| M. veatchiana
|