Publication: Fl. N. Amer. 2: 334.
selected vouchers: WTU
Notes: FNA20: "Two infraspecific taxa within Helianthella uniflora may be distinguished; they have been named at varietal rank.
Variety douglasii has stems hirsute; involucres (15–)20–25(–30) mm diam.; outer phyllaries rarely elongated, margins ciliate, abaxial faces sparsely puberulent; ray laminae 30–40 mm; and 2n = 30. It grows in grasslands in the northern Rocky Mountains and on the east side of the Cascade Range (B.C.; Idaho, Oreg., Wash.) at 300–2500 m where it flowers May–Jul."
See Weber (1952)