4.
Helianthella uniflora
(Nuttall) Torrey & A. Gray, Fl. N. Amer. 2: 334. 1842.
Helianthus uniflorus
Nuttall, J. Acad. Nat. Sci. Philadelphia 7: 37. 1834;
Helianthella uniflora
var.
douglasii
(Torrey & A. Gray) W. A. Weber
Plants
40—120 cm.
Cauline leaves:
largest at mid stems; blades usually 3-nerved, usually lanceolate to elliptic, rarely ovate, 12—25 cm, faces puberulent, hirsute, or scabrous.
Heads
usually borne singly, sometimes 2—3+, erect.
Involucres
turbinate to hemispheric or broader, 15—30 mm diam.
Phyllaries
lanceolate to lance-linear (subequal or outer larger, margins sometimes ciliate, faces ± cinereous-pubescent to sparsely puberulent).
Paleae
chartaceous, relatively firm.
Ray florets
11—13(—21); laminae 15—30(—45) mm.
Disc corollas
yellow.
Cypselae
strongly compressed, narrowly obovate (margins ciliate, faces strigose);
pappi
of 2 ± subulate scales plus 2—4 shorter scales.
2n
= 30.
Flowering May—Jul(—Aug). Grasslands, meadows, sagebrush scrublands, swales, aspen forests, rocky slopes, and spruce-fir forests; 300—3400 m; B.C.; Ariz., Colo., Idaho, Mont., Nev., Oreg., Utah, Wash., Wyo.
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 2
n
= 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.
Variety
uniflora
has stems sparingly puberulent to scabrous; involucres 15—20(—25) mm diam.; outer phyllaries frequently elongated, margins not ciliate, abaxial faces uniformly cinereous-pubescent; ray laminae 20—30 mm; and 2
n
= 30. It grows in meadows, sagebrush scrublands, swales, aspen forests, rocky slopes, and spruce-fir forests of the Rocky Mountains, intermountain plateaus, and Great Basin ranges (Ariz., Colo., Idaho, Mont., Nev., Oreg., Utah, Wyo.) at 1500—3400 m, where it flowers (May—)Jun—Jul(—Aug).
