Horkelia tridentata var. flavescens

(Rydberg) Ertter & Reveal

Novon 17: 320. 2007.

Common names: Hairycup horkelia
Endemic
Basionym: Horkelia flavescens Rydberg Monogr. N. Amer. Potentilleae, 138, plate 75. 1898
Synonyms: H. tridentata subsp. flavescens (Rydberg) D. D. Keck Potentilla tilingii var. flavescens (Rydberg) J. T. Howell
Treatment appears in FNA Volume 9. Treatment on page 270. Mentioned on page 268, 269.

Stems ± decumbent, 0.5–2.5(–4.5) dm. Inflorescences composed of usually 1 3–25-flowered ± corymbiform cluster. Flowers 6–10 mm diam.; hypanthium 2.5–5 mm diam., interior pilose (except in some North Coast Ranges populations); petals ± broadly oblanceolate, (1–)1.5–3(–4) × 0.5–1.5 mm, often shorter than sepals, apex obtuse to rounded or mucronate; filaments 1–2 × 0.2–0.4(–0.8) mm, anthers 0.3–0.5 mm; styles 1.5–2.5 mm. Achenes 2–2.5 mm, strongly rugose.


Phenology: Flowering summer.
Habitat: Open areas, primarily in conifer woodlands, often on serpentine soil
Elevation: 700–2000 m

Discussion

Variety flavescens occurs primarily in the mountains of northwestern California, from Mendocino to Siskiyou counties. A single collection is confirmed from Curry County, Oregon (Bear Camp Trail, Leach 4554, OSC); other collections from Curry and Josephine counties may be hybrids between this variety and Horkelia congesta var. nemorosa. A second cluster of populations occurs in central Plumas and adjacent Lassen counties, California, and historic collections are known from near Truckee on the border of Nevada and Placer counties, California. D. D. Keck (1938) suggested that this bicentric distribution may have resulted from the independent coalescence of the diagnostic characteristics of var. flavescens. The locality of a collection purportedly from Washoe County, Nevada (80 miles north of Reno, Brooks s.n., RENO) needs to be confirmed.

Selected References

None.

Lower Taxa

None.
Barbara Ertter +  and James L. Reveal +
(Rydberg) Ertter & Reveal +
Horkelia flavescens +
Hairycup horkelia +
Calif. +  and Oreg. +
700–2000 m +
Open areas, primarily in conifer woodlands, often on serpentine soil +
Flowering summer. +
H. tridentata subsp. flavescens +  and Potentilla tilingii var. flavescens +
Horkelia tridentata var. flavescens +
Horkelia tridentata +
variety +