Ivesia pickeringii
Pickering's ivesia, silky mousetail
ascending to erect, 3–5 dm.
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.
5–10.
10–100-flowered, (1.5–)5–15 cm diam., flowers usually arranged individually, sometimes more congested.
(1–)2–10 mm.
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.
dark brown, 2.5–3 mm.
Ivesia pickeringii
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.)
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