Horkelia sericata |
Horkelia howellii |
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Howell's horkelia, silky horkelia |
Howell's horkelia, Klamath horkelia |
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Habit | Plants ± tufted, silvery. | Plants tufted to openly matted, ± green. |
Stems | ascending to erect, 1.5–4.5 dm, hairs 1 mm proximally, glands absent or sparse distally. |
ascending to erect, (0.9–)1.5–5 dm, hairs 1 mm proximally, glands absent or sparse distally. |
Basal leaves | ± cylindric to weakly planar, 3–10 × 0.3–1.2 cm, densely sericeous, often villous on margins apically; stipules usually entire or forked, rarely pinnately divided into linear lobes; leaflets (8–)10–20 per side, ± overlapping, elliptic to flabellate, 2–8 × 1–4 mm, 1/2–2/3 as wide as long, divided ± 1/2+ to midrib into (0–)2–4 elliptic lobes 1–2 mm wide, these not restricted to apex. |
± 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. |
Cauline leaves | (2 or)3–5; stipules 3–8 mm, entire or shallowly 1–2-toothed. |
(2 or)3–5; stipules 5–12(–15) mm, entire to deeply 2–4-lobed or -toothed (usually on 1 side). |
Inflorescences | open, flowers arranged individually and/or in non-capitate glomerules. |
open, flowers arranged individually and/or in non-capitate glomerules. |
Pedicels | 1–4 mm. |
1–6(–12) mm. |
Flowers | 10 mm diam.; epicalyx bractlets linear-lanceolate, 1.5–3 × 0.5 mm, ± 2/3 length of sepals; hypanthium 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, 2–4 mm; petals white to pink or red-veined, narrowly obcordate, 3–4.5(–7) × 2–3 mm, apex ± emarginate; filaments 0.5–1.5 × 0.2–0.5 mm, anthers 0.4–0.6 mm; carpels 2–6; styles 1.5–2 mm. |
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. |
Achenes | brown, 2–2.5 mm, smooth. |
brown, 2–2.7 mm, smooth. |
2n | = 28. |
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Horkelia sericata |
Horkelia howellii |
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Phenology | Flowering summer. | Flowering summer. |
Habitat | Chaparral, oak-conifer woodlands, on serpentine-derived soil | Chaparral, oak-conifer woodlands, mainly on serpentine soil |
Elevation | 100–1200 m (300–3900 ft) | 60–1200 m (200–3900 ft) |
Distribution |
CA; OR
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CA; OR
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Discussion | Of conservation concern. D. D. Keck (1938) expanded the circumscription of Horkelia sericata to encompass the plants segregated here as H. howellii, on the grounds that intergradation is too extensive to justify taxonomic recognition of the extremes. In this evaluation, however, most collections can be unequivocally divided between plants with compact silvery-sericeous leaves with entire or forked stipules (H. sericata), and plants with larger, greener leaves and pinnately divided stipules (H. howellii). It is not known if the chromosome count provided by P. A. Munz (1959) was derived from H. howellii or H. sericata. As here circumscribed, Horkelia sericata is a localized taxon known only from Curry County, Oregon, and the Gasquet serpentine area in adjacent Del Norte County, California. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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.) |
Source | FNA vol. 9, p. 265. | FNA vol. 9, p. 265. |
Parent taxa | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Tridentatae | Rosaceae > subfam. Rosoideae > tribe Potentilleae > Horkelia > sect. Tridentatae |
Sibling taxa | ||
Synonyms | Potentilla sericata | Potentilla howellii |
Name authority | S. Watson: Proc. Amer. Acad. Arts 20: 364. (1885) | (Greene) Rydberg: Bull. Torrey Bot. Club 25: 55. (1898) |
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