| 1. Annual (may germinate in winter); < 2500 m; styles generally << 0.2 mm |
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| 2. Petals divided > 1/4 to base, white; leaves basal |
| D. verna |
| 2' Petals entire or divided < 1/8 to base, white or light yellow; leaves basal and generally also cauline |
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| 3. Lowest pedicel > 2 × fruit; petals light yellow, not markedly smaller in lateral inflorescences |
| D. nemorosa |
| 3' Lowest pedicel < 2 × fruit; petals white, often smaller or 0 in lateral inflorescences |
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| 4. Leaf generally dentate; fruits lanceolate to oblong, often loosely clustered; inflorescence axes generally hairy |
| D. cuneifolia |
| 4' Leaf generally entire (to slightly dentate); fruits ± linear, densely clustered; inflorescence axes glabrous |
| D. reptans |
| 1' Biennial to perennial herb; generally > 2000 m; styles generally conspicuous, generally > 0.2 mm (if shorter, go to 22. and 22') |
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| 5. Longest styles > 1 mm; corolla yellow |
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| 6. Stem hairs coarse; basal leaves generally > 10 mm; cauline leaves generally several; fruits generally > 30 per inflorescence, sometimes densely clustered |
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| 7. Fruit (3)46 mm wide, not twisted, tip obtuse; Klamath Ranges, High Cascade Range |
| D. aureola |
| 7' Fruit (1.5)23(4) mm wide, generally twisted, tip acute; Transverse Ranges, Peninsular Ranges |
| D. corrugata |
| 8. Cauline leaves 315, often crowded; fruits densely clustered |
| var. corrugata |
| 8' Cauline leaves 03, not crowded; fruits sparsely clustered |
| var. saxosa |
| 6' Stem hairs generally 0 above or fine (except some D. howellii); basal leaves generally < 10 mm (except some D. howellii); cauline leaves generally 0 (or 13, bract-like); fruits generally < 30 per inflorescence, not densely clustered |
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| 9. Leaf narrowly ovate, tip generally acute; fruit lanceolate, strongly twisted; seed wing 0; s High Sierra Nevada |
| D. sharsmithii |
| 9' Leaf oblanceolate to obovate, tip generally rounded; fruit elliptic to ovate, little twisted; seed winged (except D. howellii); Klamath Ranges, n Sierra Nevada |
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| 10. Leaf with tangled, generally irregularly branched hairs on lower surface, hairs on margin long |
| D. pterosperma |
| 10' Leaf with non-tangled, generally 27-branched, generally stellate hairs (or glabrous) on lower surface, hairs on margin 0 or seldom long |
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| 11. Seed wing 0; cauline leaves generally 13, bract-like; fruit generally hairy |
| D. howellii |
| 11' Seed wing wide; cauline leaves (or bracts) generally 0; fruit generally glabrous |
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| 12. Leaf surface hairs generally 47-branched-stellate, margin glabrous; stems fewmany from below; n High Sierra Nevada |
| D. asterophora var. macrocarpa |
| 12' Leaf surfaces glabrous, margin hairs 24-branched; stems 1few from base; Klamath Ranges |
| D. carnosula |
| 5' Longest styles < 1 mm; corolla white to yellow |
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| 13. Corolla yellow; leaves basal; stems ± cushion- or mat-forming; seeds generally > 1 mm |
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| 14. Leaves entire to minutely dentate, not persistent, not densely overlapped; fruit narrowly lanceolate, hairs generally 0 or sparse, short |
| D. cruciata |
| 14' Leaves entire, persistent, densely overlapped; fruit generally ± ovate, hairs 0 or often some long |
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| 15. Leaf obovate, thick, ± fleshy, generally > 3 mm wide |
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| 16. Leaf hairs generally 4-branched-stellate, margin glabrous; seed winged |
| D. asterophora var. asterophora |
| 16' Leaf hairs simple or forked, generally prominent on margin; seed wing 0 |
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| 17. Herbage glabrous or sparsely hairy; fruit generally not wavy, not twisted |
| D. incrassata |
| 17' Herbage hairy; fruit often wavy or twisted |
| D. lemmonii var. lemmonii |
| 15' Leaf linear to oblanceolate, ± thin, 0.53 mm wide |
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| 18. Leaf margin prominently stiff-hairy |
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| 19. Leaf lower surface glabrous or sparsely short-branched-hairy |
| D. densifolia |
| 19' Leaf lower surface with long, branched hairs |
| D. paysonii var. treleasei |
| 18' Leaf margin glabrous (or hairs not very prominent) |
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| 20. Stem hairs 0 or stellate; leaf hairs not bush-like, main axis obvious |
| D. oligosperma var. oligosperma |
| 20' Stem hairs bush-like; leaf hairs ± bush-like or stellate, main axis not obvious |
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| 21. Fruit strongly compressed, generally twisted |
| D. sierrae |
| 21' Fruit swollen at base, not twisted |
| D. subumbellata |
| 13' Corolla generally white to cream-colored (except D. albertina); leaves basal and generally also cauline; stems sometimes ± tufted (not mat-forming); seeds generally < 1 mm |
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| 22. Stellate hairs with 4 or fewer branches |
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| 23. Leaf lower surface with forked and cross-shaped hairs; corolla yellow; stem 140 cm; fruits 420 mm, not in umbel-like clusters; seed 0.71 mm |
| D. albertina |
| 23' Leaf lower surface with simple and forked hairs; corolla white; stem < 10 cm; fruits 35 mm, in umbel-like clusters; seed 0.60.8 mm |
| D. monoensis |
| 22' Some stellate hairs with > 4 branches |
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| 24. Fruit linear, generally > 10 mm, 12 mm wide |
| D. lonchocarpa var. lonchocarpa |
| 24' Fruit narrowly lanceolate to oblong or ± ovate, generally < 10 mm, generally > 2 mm wide |
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| 25. Leaf lower surface with 48-branched, stellate hairs, generally gray-green; lower pedicels > 3 mm, ascending; fruit not twisted, glabrous or hairs simple and forked |
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| 26. Stem < 10(15) cm, with fruit ± throughout; cauline leaves overlapped |
| D. californica |
| 26' Stem 1035 cm, with fruit only above middle; cauline leaves not overlapped |
| D. praealta |
| 25' Leaf lower surface with dense, many-branched, stellate hairs, generally whitish; lower pedicels generally < 3 mm, appressed; fruit twisted or not, with generally > 3-branched, stellate hairs |
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| 27' Cauline leaves generally entire; lower flowers not bracted |
| D. breweri |
| 27. Cauline leaves toothed; lower flowers generally bracted |
| D. cana
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