Horkelia howellii |
Horkelia tenuiloba |
|
---|---|---|
Howell's horkelia, Klamath horkelia |
Santa Rosa, Santa Rosa horkelia, Sonoma horkelia, thin-lobed, thin-lobed horkelia |
|
Habit | Plants tufted to openly matted, ± green. | Plants loosely matted, green. |
Stems | ascending to erect, (0.9–)1.5–5 dm, hairs 1 mm proximally, glands absent or sparse distally. |
ascending to erect, 1–4 dm, hairs ± spreading. |
Basal leaves | ± cylindric to weakly planar, 5–15 × 0.5–1.8(–2.5) cm, usually villous to pilose at least marginally, often glabrescent; stipules deeply 2-lobed or pinnately divided into 3–5 linear to filiform lobes that often form a tangled mass; leaflets 10–15 per side, ± overlapping, elliptic to flabellate, (3–)4–10(–15) × 2–8 mm, 1/2 to as wide as long, divided 1/2–3/4 to midrib into (0–)2–4 elliptic to linear lobes 1–2 mm wide, these not restricted to apex. |
weakly planar to ± cylindric, 5–15(–20) × 0.5–1.5 cm; stipules entire; leaflets 8–16(–20) per side, ± overlapping especially distally, cuneate to flabellate, 3–10 × 2–10 mm, 1/2 to nearly as wide as long, divided 1/2–3/4+ to midrib into 3–8 linear to narrowly oblanceolate or narrowly elliptic lobes, sparsely villous at least marginally, often with a tuft of hairs apically. |
Cauline leaves | (2 or)3–5; stipules 5–12(–15) mm, entire to deeply 2–4-lobed or -toothed (usually on 1 side). |
2–5. |
Inflorescences | open, flowers arranged individually and/or in non-capitate glomerules. |
open to congested, flowers arranged individually and in glomerules, these sometimes subcapitate. |
Pedicels | 1–6(–12) mm. |
1–6 mm. |
Flowers | 10 mm diam.; epicalyx bractlets linear-lanceolate, 1–3 × 0.5 mm, ± 2/3 length of sepals; hypanthium 1.1–1.5 × 2–3 mm, ± 1/2 to as deep as wide, interior glabrous; sepals spreading to reflexed, abaxially green to reddish or purplish, 2.5–4.5 mm; petals white to pink or red-veined, narrowly obcordate, 3–5 × 2–3 mm, apex truncate or emarginate; filaments 0.5–1.7 × 0.2–0.5 mm, anthers 0.4–0.6 mm; carpels 2–6; styles 1.5–2 mm. |
10 mm diam.; epicalyx bractlets narrowly to broadly lanceolate, 1–3 × 0.5–1 mm, slightly shorter than sepals, entire; hypanthium 1–1.2 × 2.5–4.5 mm, less than 1/2 as deep as wide, interior pilose; sepals spreading to reflexed, lanceolate, 3–5 mm; petals oblanceolate, 2.5–4.5 × 1.5 mm, apex emarginate; filaments (1–)1.5–2 × 0.5 mm, anthers 0.4–0.6 mm; carpels 10–25; styles 1.8–2.2 mm. |
Achenes | brown, 2–2.7 mm, smooth. |
light brown, 1.5 mm, smooth or slightly rugose. |
2n | = 28. |
|
Horkelia howellii |
Horkelia tenuiloba |
|
Phenology | Flowering summer. | Flowering summer. |
Habitat | Chaparral, oak-conifer woodlands, mainly on serpentine soil | Sandy soil, openings, in chaparral, oak woodlands |
Elevation | 60–1200 m (200–3900 ft) | 50–500 m (200–1600 ft) |
Distribution |
CA; OR
|
CA
|
Discussion | Of conservation concern. As noted above, Horkelia howellii comprises the bulk of what D. D. Keck (1938) and subsequent floras included in H. sericata, and the range of the latter is fully encompassed within that of the former. As here circumscribed, H. howellii occurs in northwestern California and southwestern Oregon. The handful of collections from Humboldt and Trinity counties, California, including the type of Potentilla laxiflora Drew, have leaves approaching H. daucifolia but the inflorescence of H. howellii; exact petal color is uncertain. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Horkelia tenuiloba occurs on the western edges of the northern Coast Ranges in Marin, Mendocino, and Sonoma counties. Populations from San Luis Obispo formerly included in this species now are part of H. yadonii. A specimen (M. K. C[urran], July 5, 1885, UC) unequivocally of H. tenuiloba purportedly from San Luis Obispo is in all likelihood mislabeled with respect to locality. Horkelia tenuiloba is commonly associated with seral openings in chaparral and woodlands and might be dependent on periodic disturbance by fire. W. L. Jepson (1909–1943, vol. 2) used Potentilla stenoloba (1895) for the species encompassing the types of Horkelia tenuiloba and P. micheneri. The epithet micheneri (1893) has priority at species rank within Potentilla, since P. tenuiloba (Torrey) Greene is a later homonym of P. tenuiloba Jordan. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 265. | FNA vol. 9, p. 252. |
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Tridentatae | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Horkelia |
Sibling taxa | ||
Synonyms | Potentilla howellii | H. fusca var. tenuiloba, Potentilla micheneri, P. stenoloba |
Name authority | (Greene) Rydberg: Bull. Torrey Bot. Club 25: 55. (1898) | (Torrey) A. Gray: Proc. Amer. Acad. Arts 6: 529. (1865) |
Web links |
|