Ivesia pickeringii |
Ivesia webberi |
|
---|---|---|
Pickering's ivesia, silky mousetail |
Webber's ivesia, wire ivesia, wire mousetail |
|
Habit | Plants grayish green; glands abundant. | Plants ± green, ± rosetted; taproot slender to ± stout, not fleshy. |
Stems | ascending to erect, 3–5 dm. |
decumbent to ascending, 0.5–1.5(–1.8) dm. |
Basal leaves | 8–20 cm; sheathing base ± strigose abaxially; stipules linear to narrowly lanceolate, 3–5 mm; petiole 1–3.5 cm, hairs abundant, ascending to spreading, 1–2 mm; leaflets 35–50 per side, loosely overlapping, 2–6 mm, lobes 3–5, oblanceolate to obovate or oval, hairs abundant, ± ascending, 1–2(–3) mm. |
loosely ± cylindric, 3–7(–10) cm; sheathing base ± strigose abaxially; petiole 0.5–5(–6) cm, hairs 2–4 mm; leaflets 4–8(–10) per side, (0.5–)3–8(–10) mm, loosely long-strigose or -villous and short-hirsute, ± glandular, lobes 2–5(–12), linear to lanceolate, apex not setose. |
Cauline leaves | 5–10. |
2, paired. |
Inflorescences | 10–100-flowered, (1.5–)5–15 cm diam., flowers usually arranged individually, sometimes more congested. |
5–15(–25)-flowered, 1.5–3(–6) cm diam.; glomerules 1. |
Pedicels | (1–)2–10 mm. |
(0.5–)1–8(–13) mm. |
Flowers | 8–13 mm diam.; epicalyx bractlets linear-lanceolate to lanceolate, (1.8–)2–2.5 mm; hypanthium cupulate to turbinate, 1.5–3 × 2.5–4 mm, often nearly as deep as wide; sepals often purple-suffused or -mottled, (2.5–)3–5 mm, acuminate; petals white, becoming pink-tinged with age, oblanceolate to narrowly spatulate, (2.8–)3–5(–6) mm; stamens 20, filaments filiform, 1.5–2.3 mm, anthers white to cream, 0.3–0.6 mm; carpels 2–4, styles 2.5–3.5 mm. |
9–12 mm diam.; epicalyx bractlets linear, 1.2–3 mm; hypanthium cupulate, 1–2(–2.5) × 2.5–5 mm; sepals 2.5–4.5(–5.5) mm, acute; petals yellow, narrowly oblanceolate, 2–3(–4) mm; stamens 5, filaments 1.8–2.5(–3) mm, anthers yellow, (0.8–)1–1.6 mm; carpels 3–8, styles 1.8–2.2 mm. |
Achenes | dark brown, 2.5–3 mm. |
light brown, often mottled darker brown, 1.9–2.5 mm. |
Ivesia pickeringii |
Ivesia webberi |
|
Phenology | Flowering summer. | Flowering late spring–early summer. |
Habitat | Moist, rocky, grassy meadows, mainly on ultramafic-derived clayey soil, in montane conifer woodlands | Dry flats and slopes, in sagebrush communities, conifer woodlands |
Elevation | 800–1500 m (2600–4900 ft) | (1300–)1500–1900 m ((4300–)4900–6200 ft) |
Distribution |
CA |
CA; NV |
Discussion | Of conservation concern. Ivesia pickeringii is known from Siskiyou and Trinity counties. Some early treatments (for example, P. A. Rydberg 1898, 1908–1918; W. L. Jepson [1923–1925], 1909–1943, vol. 2) conflated this species with I. aperta, hence reports of I. pickeringii in the Sierra Nevada. Historic collections from Edgewood, at the headwaters of the Shasta River in Siskiyou County, have inflorescences more glomerulate than elsewhere in the species range. The chromosome count of 2n = 28 (P. A. Munz 1959) needs confirmation. If based on Kruckeberg 3665, which was distributed as a voucher for that count, the determination of this collection has been changed to Ivesia sericoleuca. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Of conservation concern. Ivesia webberi is known only from the eastern foothills of the northern Sierra Nevada and scattered ranges to the east in California and adjacent Nevada. It is among the more distinctive species in the genus and is only tentatively placed in sect. Ivesia. The leaflets are loosely incised into slender, sparsely villous segments, and the two cauline leaves are paired with dissected stipules. Previous reports of the stems and inflorescence branches being glandular-puberulent are due to a misinterpretation of the minute pustulose bases associated with the villous indumentum as being enlarged glands. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 239. | FNA vol. 9, p. 236. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Potentilla pickeringii | Potentilla webberi |
Name authority | Torrey ex A. Gray: Proc. Amer. Acad. Arts 6: 531. (1865) | A. Gray: Proc. Amer. Acad. Arts 10: 71. (1874) |
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