| | 1. Herbage ± glandular, sometimes sticky or strong-smelling |
| |
| | 2. Plant ± sprawling; calyx minutely 3–5-toothed, obovoid, netted, tube enclosing fruit |
| C. multifidum |
| | 2' Plant generally erect; calyx deeply 5-lobed, ± spheric, not netted, lobes generally folded over fruit |
| |
| | 3. Inflorescence ± spheric, 3–6 mm diam, axillary; sepals yellow-glandular; seed generally vertical; longest leaves < 30 mm |
| C. pumilio |
| | 3' Inflorescence spike or panicle-like, 10+ mm, sometimes terminal; sepals glabrous to short-stalked-glandular; seed generally horizontal; longest leaves 30–120 mm |
| |
| | 4. Inflorescence branches straight; flowers sessile; sepals glabrous to sparsely sessile-glandular; fruit wall free from seed |
| C. ambrosioides |
| | 4' Inflorescence branches curved; flowers short-pedicelled; sepals densely short-stalked-glandular; fruit wall adherent to seed |
| C. botrys |
| | 1' Herbage glabrous to minutely scaly or powdery, generally not strong-smelling |
| |
| | 5. Perennial from stout, fleshy caudex; calyx tube generally > lobes in fruit |
| C. californicum |
| | 5' Annual; calyx tube generally < lobes |
| |
| | 6. Most seeds vertical; calyx lobes generally 3(–4) — horizontal seeds few, with 4–5 calyx lobes |
| |
| | 7. Upper inflorescences axillary, ± spheric, < 10 mm diam |
| |
| | 8. Lower leaf blades lanceolate to deltate, generally glabrous below; sepals thickened or ± fleshy in fruit |
| C. foliosum |
| | 8' Lower leaf blades oblong to ovate, densely powdery below; sepals thin or membranous in fruit — vertical and horizontal seeds generally ± equal in number |
| 2 C. glaucum |
| | 7' Upper inflorescences axillary or terminal, spike-like, 15+ mm |
| |
| | 9. Vertical seeds enclosed by calyx tube; style lobes ascending |
| |
| | 10. Young leaves glabrous or sparsely powdery; calyx lobes abruptly pointed |
| C. chenopodioides |
| | 10' Young leaves densely white-powdery; calyx lobes rounded to acute |
| C. macrospermum var. halophilum |
| | 9' Vertical seeds subtended by calyx tube; style lobes spreading |
| |
| | 11. Leaf densely powdery below; vertical & horizontal seeds often ± equal in number |
| 2 C. glaucum |
| | 11' Leaf generally glabrous below; vertical seeds many more than horizontal |
| C. rubrum |
| | 6' Most or all seeds horizontal; calyx lobes generally 5 |
| |
| | 12. Leaf bright green, deeply 3–5-lobed, base truncate to cordate, tip acuminate to long-tapered; fruit 1.5–3 mm diam |
| C. simplex |
| | 12' Leaf dull green to grayish, entire to toothed, base tapered to acute, tip rounded to acute; fruit generally < 1.5 mm diam |
| |
| | 13. Lower leaf blades 1-veined from base |
| |
| | 14. Lower leaf blades > 4 mm wide; calyx lobes strongly keeled in fruit; fruit wall free from seed, easily detached with dissecting needle |
| 2 C. desiccatum |
| | 14' Lower leaf blades < 3.5 mm wide; calyx lobes weakly keeled in fruit; fruit wall adherent to seed, firm or fracturing when teased with dissecting needle |
| C. leptophyllum |
| | 13' Lower leaf blades 3-veined from base |
| |
| | 15. Fruit wall free from seed, easily detached with dissecting needle |
| |
| | 16. Leaf length < 1.5 × width |
| |
| | 17. Fruit top visible between calyx lobes; fruit 1–1.5 mm diam; leaf blade thin |
| C. fremontii |
| | 17' Fruit top hidden by calyx lobes; fruit ± 1 mm diam; leaf blade thick, becoming ± leathery |
| C. incanum var. occidentale |
| | 16' Leaf length generally 1.5+ × width |
| |
| | 18. Stems several from base, branches ± dense; fruit ± 1 mm diam, top hidden by calyx lobes |
| 2 C. desiccatum |
| | 18' Stems 1–few from base, branches well spaced; fruit 1–1.5 mm diam, top visible between calyx lobes |
| |
| | 19. Lower leaves entire, length 1.5–3 × width |
| C. atrovirens |
| | 19' Lower leaves ± 1–2-lobed (-toothed), length 3–5 × width |
| C. pratericola |
| | 15' Fruit wall adherent to seed, firm or fracturing when teased with dissecting needle |
| |
| | 20. Stems mostly prostrate to ascending |
| |
| | 21. Leaf blade oblong to lanceolate, length generally 2+ × width, base tapered; petiole < blade |
| C. carnosulum var. patagonicum |
| | 21' Leaf blade widely elliptic to ovate, length < 1.5 × width, base obtuse to rounded; petiole ± = blade |
| C. vulvaria |
| |
| | 22. Lower leaf blade generally entire or 1–2-toothed at base |
| |
| | 23. Plant generally much-branched, ± wide; inflorescence often rounded in fruit; fruit < 1 mm diam |
| C. nevadense |
| | 23' Plant generally few-branched, slender; inflorescence mostly spikes, ascending to erect; fruit 1–1.5 mm diam |
| |
| | 24. Lower leaves narrowly lanceolate to elliptic; fruit ± 1 mm diam |
| C. hians |
| | 24' Lower leaves ovate to ± deltate; fruit 1–1.5 mm diam |
| C. incognitum |
| | 22' Lower leaf blade few–many-toothed above base |
| |
| | 25. Fruit wall surface minutely honeycombed at 20×; calyx lobes widely keeled in fruit |
| C. berlandieri |
| | 25' Fruit wall surface smooth or irregularly rough at 20×; calyx lobes smooth to narrowly keeled |
| |
| | 26. Leaf generally shiny dark green above, glabrous to sparsely powdery below; seed sharply angled at equator |
| C. murale |
| | 26' Leaf dull green to grayish above, powdery below; seed obtusely angled or rounded at equator |
| |
| | 27. Fruit top generally visible between calyx lobes; terminal inflorescence branches often stiffly ascending or erect; lower stem branches often decumbent |
| C. strictum var. glaucophyllum |
| | 27' Fruit top generally hidden by calyx lobes; terminal inflorescence branches weak, sometimes pendent; lower stem branches 0 or generally ascending |
| |
| | 28. Fruit 1–1.5 mm diam; leaf blade length < 1.5 × width; inflorescence branches generally straight |
| C. album |
| | 28' Fruit ± 1 mm diam; leaf blade length generally 1.5–2 × width; inflorescence branches generally curved or pendent |
| C. missouriense
|