| | 1. Longest heads 5–7 mm, yellowish, in dense, spheric groups of 12–20, largest groups 11–15 mm; receptacle 5–15 × as long as wide, narrowly cylindric; middle chaff scales acuminate, ± awned, persistent, obscurely winged; very uncommon alien (subg. Filago) |
| F. pyramidata var. pyramidata |
| | 1' Longest heads 3–4.5 mm, grayish, in loose ± hemispheric groups of 1–10, all groups < 11 mm; receptacle 0.5–2 × as long as wide, expanded at tip; middle chaff scales narrowly obtuse to acute, each falling with a fruit, scarious-winged (subg. Oglifa) |
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| | 2. Leaves generally awl-like, ± stiff; outer chaff scales bent abruptly inward above fruit, tightly closed, body very hard; longest chaff scale 3.3–4.1 mm |
| F. gallica |
| | 2' Leaves generally elliptic to obovate or linear, flexible; outer chaff scales evenly curved above fruit, loosely closed, body soft to firm; longest chaff scale 2.1–3.3 mm |
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| | 3. Flowers inside innermost chaff scales 4–12, 0–2 pistillate; heads generally in groups of 4–10, restricted to forks and tips of branches, subtending leaves ± linear, generally 2 × heads or longer; stems generally leafless between lower forks, ± glabrous, purplish to black |
| F. arizonica |
| | 3' Flowers inside innermost chaff scales 12–40, 9–33 pistillate; heads generally in groups of 1–4, not restricted to forks and tips of branches, subtending leaves elliptic to obovate, generally < 1.5 × heads; stems ± evenly leafy between lower forks, cobwebby, grayish to greenish |
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| | 4. Pappus bristles of disk fruit 17–23, falling in rings; inner fruit generally papillate; lobes of disk flower generally 4, generally reddish purple; stems generally erect, not forked, central axis dominant; leaves generally oblanceolate, acute |
| F. californica |
| | 4' Pappus bristles of disk fruit 11–15, falling singly or in 2s; inner fruit generally smooth; lobes of disk flower generally 5, generally yellowish to brownish; stems generally spreading, forked (no dominant central axis); leaves generally elliptic to obovate, obtuse |
| F. depressa
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