1	Axils of basal leaves glabrous or sparsely to­men­­tose; cauline leaves 0 or 1(–2)		(2)
+	Axils of basal leaves ± densely tomentose; cauline leaves (0–)2–12		(3)
2 (1)	Peduncles 1–2 cm; corollas 2–3 mm; anthers 2 mm; cypselae 3.5–4 mm		4a Hymenopappus filifolius var. parvulus
+	Peduncles 2–10 cm; corollas 3–5 mm; anthers 2.5–3 mm; cypselae 4–6 mm		4b Hymenopappus filifolius var. nudipes
3 (1)	Terminal lobes of basal leaves 2–6 mm; phyllaries 3–7 mm; florets 10–30; corollas 2–3 mm		(4)
+	Terminal lobes of basal leaves (2–)3–50 mm; phyllaries (5–)6–14 mm; florets (15–)20–70+; corollas (2.5–)3–7 mm.		(5)
4 (3)	Plants 5–20 cm; cauline leaves 0–3; pappi 0.1–0.8 mm		4c Hymenopappus filifolius var. luteus
+	Plants 20–35 cm; cauline leaves 4–9; pappi 0.5–1.5 mm		4d Hymenopappus filifolius var. pauciflorus
5 (3)	Corollas 4–7 mm, throat lengths (2–)3–8 times lobes; anthers 3–4 mm; cypselae 5–7 mm; pappi (1.2–)1.5–3 mm		(6)
+	Corollas 2.5–4.5 mm, throat lengths 2–4(–5) times lobes; anthers 2–3 mm; cypselae 4–6 mm; pappi 0.2–2(–3) mm		(8)
6 (5)	Peduncles 8–16 cm; corollas whitish; cypselahairs 0.5–1 mm		4e Hymenopappus filifolius var. eriopodus
+	Peduncles 2–12 cm; corollas yellowish; cypsela hairs 1–2 mm		(7)
7 (6)	Cauline leaves (1–)2–6; terminal lobes of basal leaves 5–30 mm; phyllaries 8–12(–14)mm		4f Hymenopappus filifolius var. megacephalus
+	Cauline leaves 0–3; terminal lobes of basal leaves 3–15 mm; phyllaries 6–10 mm		4g Hymenopappus filifolius var. lugens
8 (5)	Cauline leaves (2–)3–8; heads 5–60; corolla throats 1.3–1.8 mm		4h Hymenopappus filifolius var. polycephalus
+	Cauline leaves 0–5(–12); heads 1–10(–40); corolla throats 1.5–2.5 mm		(9)
9 (8)	Terminal lobes of basal leaves 3–6 mm; caul-ine leaves 5–12		4i Hymenopappus filifolius var. tomentosus
+	Terminal lobes of basal leaves 2–50 mm; cauline leaves 0–5		(10)
10 (9)	Plants 30–100 cm; terminal lobes of basal leaves 15–50 mm; pappi 0.2–1 mm		4j Hymenopappus filifolius var. filifolius
+	Plants 5–50 cm; terminal lobes of basal leaves 2–30 mm; pappi (0.6–)1–3 mm		(11)
11 (10)	Peduncles 3–15 cm; cypsela hairs 0.1–1 mm; pappi 1.5–3 mm		4k Hymenopappus filifolius var. nanus
+	Peduncles 1–6 cm; cypsela hairs 1–3 mm; pappi 0.6–2 mm		(12)
12 (11)	Cauline leaves 0–2; cypsela hairs 1 mm; pappi 0.6–1.3 mm		4l Hymenopappus filifolius var. idahoensis.
+	Cauline leaves (0–)2–4; cypsela hairs 1–3 mm; pappi 1.5–2 mm		4m Hymenopappus filifolius var. cinereus