1. Plants annual, biennial, or perennial; mericarps: dehiscent part 10–75% of height, indehiscent part ± equaling to usually wider than dehiscent part | → 2 |
1. Plants perennial; mericarps: dehiscent part 50–85% of height, indehiscent part usually not notably wider than dehiscent part | → 9 |
2. Leaf blade surfaces silvery stellate-lepidote. | S. leptophylla |
2. Leaf blade surfaces stellate-pubescent or stellate-canescent | → 3 |
3. Plants annual; mericarps 1.5–2 mm; leaf blades gray-green pubescent, unlobed or 3–5-lobed. | S. coulteri |
3. Plants usually perennial, sometimes annual or biennial; mericarps 2–5.5 mm; leaf blades green, pale green, yellow, yellow-green, or gray, light gray, or gray-green pubescent, unlobed, or if green or gray to green pubescent, leaves unlobed, 3–5-lobed, or pedately divided | → 4 |
4. Leaf blades trullate or triangular, not deeply divided. | S. orcuttii |
| → 7 |
6. Sepals 5–13 mm; petals 15–20(–25) mm | S. gierischii |
6. Sepals 4.5–8.5 mm; petals 8–15 mm | S. moorei |
7. Leaf blades pedately divided, lobes relatively narrow | S. pedatifida |
7. Leaf blades usually 3–5-lobed, sometimes pedately divided with relatively broad lobes | → 8 |
8. Leaf blades 3–5-lobed or pedately divided, green to gray-green, stellate-canescent; bractlets deciduous. | S. coccinea |
8. Leaf blades 3–5-lobed, yellow-green, sparsely stellate-canescent, bractlets persistent. | S. psoraloides |
9. Inflorescences usually racemose, sometimes paniculate | → 10 |
9. Inflorescences paniculate | → 15 |
10. Leaf blades 3-lobed to pedately divided; inflorescences racemose. | S. digitata |
10. Leaf blades unlobed, 3-lobed, or pedately divided; inflorescences racemose or paniculate | → 11 |
11. Stems decumbent; leaf blades abaxially white to silvery, adaxially green; coastal Texas. | S. lindheimeri |
11. Stems usually ascending to erect, sometimes decumbent; leaf blades green, yellow-green, or gray-green; w Texas and sw United States | → 12 |
12. Leaf blades ovate to deltate, unlobed or 3-lobed | → 13 |
12. Leaf blades oblong-ovate to ovate-lanceolate and unlobed, or widely ovate or triangular to orbiculate and pedately divided | → 14 |
13. Stems 5–10 dm; widely distributed. | S. ambigua |
13. Stems 2–2.5 dm; restricted to Beaver and Millard counties, Utah, or Nye County, Nevada. | S. caespitosa |
14. Leaf blades unlobed; sepals forming beak in bud. | S. hastulata |
14. Leaf blades usually pedately divided (all but proximalmost); sepals not forming beak in bud. | S. wrightii |
| → 16 |
16. Leaf blades unlobed or weakly 3-lobed; stems yellow- to yellow-green canescent or gray- to white-canescent; anthers yellow, gray, or purple; petals red-orange, apricot, lavender, pink, or white. | S. ambigua |
16. Leaf blades 3-lobed or 3- or 5-parted; stems gray- to white-tomentose; anthers usually purple; petals red-orange. | S. laxa |
17. Leaf blades linear to lanceolate or broadly trullate, unlobed to hastately lobed to angulate; inflorescences usually with leaves throughout. | S. angustifolia |
18. Leaf blades unlobed, elongate-deltate, oblong-ovate, ovate-lanceolate, lanceolate, triangular, ovate, or deltate, or weakly 3–5-lobed | → 19 |
18. Leaf blades usually strongly 3–5-lobed or pedately divided | → 22 |
19. Stems yellow to yellow-green, rubbery; leaf blades deltate or elongate-deltate, sometimes lobed, center lobe sometimes elongate, lobes relatively broad; sepal tips not forming beak in bud. | S. incana |
20. Leaf blades oblong-ovate to ovate-lanceolate; stems 1–3(–5) dm; sepal tips forming beak in bud. | S. hastulata |
20. Leaf blades ovate to triangular, unlobed or weakly lobed; stems 1.5–10 dm; sepal tips not forming beak in bud | → 21 |
21. Stems green to gray-green canescent; leaf margins coarsely toothed; primarily Nevada, Utah, and north. | S. munroana |
21. Stems white- to yellow-canescent; leaf margins entire or crenate to serrate; primarily Nevada, Utah, and south. | S. parvifolia |
22. Leaf blades 3(–5)-lobed; stems (2–)4–30 dm | → 23 |
22. Leaf blades usually deeply lobed or pedately divided, sometimes highly dissected; stems 1–10 dm | → 26 |
23. Stems (2–)4–7(–10) dm, usually sparsely canescent or hirsute; petals red-orange. | S. fendleri |
23. Stems 10–30 dm, glabrous or hairy; petals red-orange, red, pink, white, lavender, purple, or rose-purple | → 24 |
24. Leaf blades ovate-triangular to lanceolate, 3-lobed; inflorescence tip not leafy; stem glabrous or coarse-canescent. | S. emoryi |
24. Leaf blades deltate, lanceolate, ovate, triangular, or cordate, subhastate to 3-lobed; inflorescence tip leafy; stem indument soft | → 25 |
25. Mericarps 12–14, 3.5–5.5 mm. | S. polychroma |
25. Mericarps 10, usually 3 mm. | S. procera |
| → 27 |
| → 28 |
27. Leaf blade surfaces hirsute, sparsely pubescent, or densely soft-pubescent, lobed, appearing green to gray-green. | S. fendleri |
27. Leaf blade surfaces stellate-pubescent, commonly lobed or pedately divided, appearing yellow-green to gray-green to green. | S. grossulariifolia |
28. Stems green to gray-green; bractlets and leaf margins not red, reddish, or purple, usually green or tan. | S. hastulata |
28. Stems gray-green to purple (red-purple basally in S. fumariensis); bractlets and sometimes leaf margins red, reddish, or purple | → 29 |
29. Leaf blades densely stellate-pubescent; anthers yellow; mericarps 10–14, 3–4 mm. | S. fumariensis |
29. Leaf blades sparsely stellate-pubescent; anthers usually red to purple, sometimes yellow; mericarps 13, 4.5–6 mm. | S. rusbyi |