| | 1. Perennial, subshrub, or shrub |
| |
| | 2. Perennial; central stem herbaceous to ± woody at base |
| |
| |
| | 4. Fruit bracts 2–3 mm, obovate; coastal |
| 2 A. coulteri |
| | 4' Fruit bracts 3–5 mm, obovate to subspheric; inland |
| 2 A. fruticulosa |
| | 3' Stems generally prostrate to decumbent |
| |
| | 5. Cauline leaves generally opposite; plants mat-like, monoecious or dioecious |
| |
| | 6. Leaves thin, gray-scaly, sometimes thinly so above; fruit bracts sharply dentate; generally monoecious |
| 2 A. coulteri |
| | 6' Leaves thick to ± fleshy, densely white-scaly; pistillate fruit bracts (sub)entire; generally dioecious |
| A. watsonii |
| | 5' Cauline leaves generally alternate; plants not mat-like; generally dioecious |
| |
| | 7. Fruit bracts ± free, ± compressed, ± thin; staminate and pistillate flowers generally in same clusters |
| A. californica |
| | 7' Fruit bracts fused to middle or above, thick, spongy to fleshy; pistillate inflorescence generally below staminate inflorescence |
| |
| | 8. Fruit bracts fleshy, reddish, 3–6 mm |
| A. semibaccata |
| | 8' Fruit bracts spongy, gray to white, 4–12 mm |
| |
| | 9. Leaf blade elliptic to widely ovate; fruit bracts fused ± to middle, body ± subspheric; seeds alike, 2–3 mm; coastal |
| A. leucophylla |
| | 9' Leaf blade oblanceolate to diamond-shaped; fruit bracts fused to near top, body ± widely obconic; seeds of 2 forms, ± 1 mm or ± 1.5 mm; inland |
| 2 A. lindleyi |
| | 2' Subshrub or shrub, central stem aboveground clearly woody |
| |
| | 10. Fruit bracts together 4-winged base to top |
| A. canescens |
| | 11. Leaf blade 3–8 mm wide; fruit bracts stalked, wings generally 3–6 mm wide |
| subsp. canescens |
| | 11' Leaf blade 1–3 mm wide; fruit bracts sessile, wings generally < 3.5 mm wide |
| subsp. linearis |
| | 10' Fruit bracts together not clearly 4-winged |
| |
| | 12. Leaves generally ± wavy to toothed |
| |
| | 13. Fruit bracts free, short-stalked; leaf blade silver-scaly; East of Sierra Nevada, Desert (including edges) |
| A. hymenelytra |
| | 13' Fruit bracts fused ± to middle, sessile; leaf blade gray-scaly; South Coast |
| A. nummularia |
| | 12' Leaves generally entire |
| |
| | 14. Stems several–many from base, generally unbranched; fruit bracts fusiform to ovoid — tips long-tapered |
| A. gardneri var. falcata |
| | 14' Stem generally 1 from base, much-branched, stiffly spreading to erect; fruit bracts ovate to ± round or ± spheric (except tips) |
| |
| |
| | 16. Fruit bracts ± free, widely elliptic to ± round, few-toothed below middle, entire above middle |
| A. confertifolia |
| | 16' Fruit bracts fused ± to middle, entire and spheric below middle, compressed and irregularly toothed above middle |
| A. spinifera |
| |
| | 17. Upper leaves generally sessile to clasping, base truncate to cordate |
| A. parryi |
| | 17' Upper leaves generally subsessile to short-petioled, base tapered to round |
| |
| | 18. Leaf blade oblong to narrowly oblanceolate, generally 2–4 mm wide |
| A. polycarpa |
| | 18' Leaf blade ovate to deltate, generally 10–50 mm wide |
| A. lentiformis |
| | 19. Twigs generally smooth, not striate |
| subsp. lentiformis |
| | 19' Twigs generally sharp-angled, striate |
| subsp. torreyi |
| |
| | 20. Leaves generally green on both surfaces, glabrous to sparsely powdery or fine-scaly |
| |
| | 21. Fruit bracts ovate to ± round; seeds on same plant of 2 sizes and colors (± 1–2 mm and black or 2–4 mm and brown) |
| |
| | 22. Fruit bracts clearly net-veined, 8–18 mm; black seeds horizontal |
| A. hortensis |
| | 22' Fruit bracts not net-veined, 2–7 mm; black seeds vertical |
| |
| | 23. Fruit bracts elliptic to ± round, surfaces smooth, margins entire |
| A. heterosperma |
| | 23' Fruit bracts ovate to widely triangular, surfaces 2-tubercled, margins few-toothed |
| A. subspicata |
| | 21' Fruit bracts ± triangular; seeds on same plant ± all alike |
| |
| | 24. Fruit bracts fused to near top |
| 2 A. serenana |
| | 24' Fruit bracts generally ± free above middle |
| |
| | 25. Fruit bract base cordate to hastate; leaves fleshy, brittle, base hastate; stems faintly striate |
| A. phyllostegia |
| | 25' Fruit bract base truncate to obtuse; leaves not fleshy, not brittle, base tapered to truncate; stems generally green-yellow-striate |
| |
| | 26. Fruit bract margin narrow, minutely dentate (especially below middle) |
| |
| | 27. Lower leaves oblong to lanceolate; fruit bract base tapered to rounded, surfaces generally smooth |
| A. patula var. patula |
| | 27' Lower leaves lanceolate to triangular; fruit bract base truncate, surfaces generally tubercled |
| A. triangularis |
| | 26' Fruit bract margin wide, entire |
| |
| | 28. Fruit bract 3–4 mm, surfaces ribbed; leaves ovate to triangular, irregularly wavy-toothed |
| 2 A. joaquiniana |
| | 28' Fruit bract 6–12 mm, surfaces smooth or tubercled; leaves linear to lanceolate, entire to finely dentate |
| A. patula var. obtusa |
| | 20' Leaves white to gray, densely and finely scaly (especially below) |
| |
| | 29. Fruit bracts ± free — stems striate |
| 2 A. joaquiniana |
| | 29' Fruit bracts fused from middle, above middle, or to near top |
| |
| | 30. Fruit bracts generally widest below middle, ovate, deltate, or diamond-shaped (sometimes ± round in A. cordulata) |
| |
| | 31. Leaves coarsely wavy-toothed; fruit bracts hard |
| A. rosea |
| | 31' Leaves generally entire; fruit bracts flexible |
| |
| | 32. Stems 0–few-branched, erect, 1–8 dm; fruit bracts 2.5–5 mm |
| |
| | 33. Lower leaves with cordate base; fruit bracts 3.5–5 mm; s Sacramento Valley, San Joaquin Valley |
| A. cordulata |
| | 33' Lower leaves with rounded base; fruit bracts 2.5–3.5 mm; s San Joaquin Valley (Kern Lake) |
| A. tularensis |
| | 32' Stems much-branched, prostrate to erect, < 4 dm; fruit bracts 1–3.5 mm |
| |
| | 34. Stems prostrate to decumbent |
| |
| | 35. Stems glabrous to densely scaly near tips; leaves alternate or opposite |
| A. depressa |
| | 35' Stems woolly near tips; leaves generally opposite |
| A. parishii |
| | 34' Stems erect (branches widely spreading) |
| |
| | 36. Fruit bracts ± 2–3 mm, ± 2–2.5 mm wide, surfaces densely tubercled; stems brittle; San Joaquin Valley |
| A. minuscula |
| | 36' Fruit bracts 1–2 mm, ± 1 mm wide, surfaces smooth; stems rigid, not brittle; Great Basin Floristic Province |
| A. pusilla |
| | 30' Fruit bracts (including stalk) generally widest at or above middle, wedge-shaped to ± round |
| |
| | 37. Staminate flowers in terminal spikes, pistillate flowers in axillary clusters |
| |
| | 38. Stems prostrate to decumbent |
| |
| | 39. Leaf blade elliptic to oblanceolate; fruit bracts 1–1.5 mm |
| A. pacifica |
| | 39' Leaf blade linear-lanceolate; fruit bracts > 3 mm |
| 2 A. fruticulosa |
| | 38' Stems generally ascending to erect |
| 2 A. serenana |
| | 40. Leaf blades 10–20 mm; staminate inflorescence spheric; fruit bracts faintly 3-veined; s South Coast |
| var. davidsonii |
| | 40' Leaf blades 15–40 mm; staminate inflorescence spike, elongate; fruit bracts ± 1-veined; widespread |
| var. serenana |
| | 37' Staminate flowers in axillary clusters (or staminate and pistillate flowers mixed, generally in axillary clusters) |
| |
| | 41. Fruit bracts spongy, 5–12 mm, top-shaped to ± spheric — San Joaquin Valley, s South Coast |
| 2 A. lindleyi |
| | 41' Fruit bracts not spongy, 2–6 mm (–8 mm in A. argentea), wedge-shaped to round, generally compressed (if spheric then densely tubercled) |
| |
| | 42. Fruit bracts round, ± dentate to cut |
| A. elegans |
| | 43. Fruit bract margin 0.5–1 mm wide, dentate to cut |
| var. elegans |
| | 43' Fruit bract margin 0.3–0.5 mm wide, minutely crenate to finely toothed |
| var. fasciculata |
| | 42' Fruit bracts generally wedge-shaped to obovate or ± spheric, entire below middle, toothed above |
| |
| | 44. Fruit bract tip generally truncate, 4–5-toothed, margin entire — generally East of Sierra Nevada, Mojave Desert (including edges) |
| A. truncata |
| | 44' Fruit bract tip acute to rounded in outline, margin toothed |
| |
| | 45. Leaf margin coarsely serrate |
| A. suberecta |
| | 45' Leaf margin entire, wavy or flat |
| |
| | 46. Leaf blade base generally hastate; fruit bracts 4–8 mm, fused to near top |
| A. argentea |
| | 47. Stems decumbent, 15–30 cm; fruit bracts sessile |
| var. hillmanii |
| | 47' Stems erect, 30–80 cm; fruit bracts short-stalked |
| |
| | 48. Upper leaves short-petioled; lowest leaves alternate; Great Basin Floristic Province |
| var. argentea |
| | 48' Upper leaves sessile; lowest leaves opposite; Great Central Valley, e San Francisco Bay Area, e South Coast, Desert |
| var. mohavensis |
| | 46' Leaf blade base tapered to ± obtuse; fruit bracts 2.5–6 mm, fused ± to middle |
| |
| | 49. Fruit bracts 2.5–4 mm, ± 2–3 mm wide |
| A. vallicola |
| | 49' Fruit bracts 4.5–6 mm, 3–4 mm wide |
| A. coronata |
| | 50. Stems decumbent to ascending; fruit bracts ± compressed, tubercles generally few, < marginal teeth |
| var. coronata |
| | 50' Stems ± erect; fruit bracts together ± spheric, tubercles dense, ± = marginal teeth |
| var. notatior
|