Ivesia pickeringii
Ivesia setosa
Pickering's ivesia, silky mousetail
bristly ivesia
ascending to erect, 3–5 dm.
± ascending to nearly erect, 0.7–2.5(–2.8) 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.
weakly planar to loosely cylindric, 5–9(–12) cm; sheathing base ± strigose abaxially;
petiole 1–8 cm;
lateral leaflets 5–10 per side, separate to overlapping distally, ± flabellate, 2–8 mm, incised ± 3/4 to base, sometimes nearly to base, into (3–)7–11 ovate teeth to narrowly obovate lobes, apex usually ± setose, surfaces ± sparsely hirsute, conspicuously glandular;
terminal leaflets ± indistinct.
5–10.
(0–)1;
blade vestigial.
10–100-flowered, (1.5–)5–15 cm diam., flowers usually arranged individually, sometimes more congested.
(1–)5–15(–30)-flowered, ± open, 1–6(–12) cm diam.
(1–)2–10 mm.
5–15(–20) 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.
7–10 mm diam.;
epicalyx bractlets 5, lanceolate, 1.3–2.5(–3) mm;
hypanthium patelliform, (1–)1.5–2 × 2–3.5(–4) mm;
sepals (1.5–)2–3.5 mm, ± acute;
petals yellow, oblanceolate to narrowly spatulate, 1.5–2.5 mm;
stamens 5, filaments 0.8–1.5 mm, anthers yellow, oblong, 0.4–0.7 mm;
carpels 2–8, styles 1.2–2 mm.
dark brown, 2.5–3 mm.
greenish white to light tan, 1.7–2 mm, smooth, ± carunculate.
Ivesia pickeringii
Ivesia setosa
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.)
Ivesia setosa occurs mostly to the east and south of I. baileyi, from southeastern Humboldt and Churchill counties to Elko, White Pine, and northern Nye counties, Nevada, and in the Deep Creek Range of western Utah. It represents a transition between the planar-leaved, chasmophytic members of sect. Setosae and the cylindric-leaved, matted species of flatter sites. Stems of I. setosa are more generally erect than in other species in the section, and the usually calcareous substrate is noteworthy. The deeply incised (usually not quite to base) leaflets are somewhat intermediate between the toothed leaflets of I. baileyi and the leaflets of I. shockleyi that are incised to the base into separate lobes. The individual leaflets of both I. baileyi and I. setosa are more or less flat and distichously paired; in I. shockleyi, groups of leaflet lobes are folded over onto each other, giving a verticillate appearance to the leaflet arrangement.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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