Ivesia arizonica
Ivesia sericoleuca
purpusia, rock whitefeather
Plumas ivesia, Plumas mousetail
pendent or prostrate to ascending, (0.2–)0.5–1.6(–3) dm.
decumbent to ascending, 1.5–4.5 dm.
planar, 2–15(–20) cm; sheathing base usually not strigose abaxially;
petiole 3–10 cm;
lateral leaflets (2–)3–4(–5) per side, separate, broadly ovate or obovate to orbiculate, (2–)5–15(–18) mm, incised 1/4–3/4 to base into (3–)7–11 ± ovate teeth, apex not setose, surfaces ± sparsely short-pilose, ± glandular;
terminal leaflets ± distinct.
10–20(–30) cm; sheathing base densely strigose abaxially;
stipules absent;
petiole 2–6(–10) cm, hairs abundant, usually spreading, 1–4 mm;
leaflets 20–35 per side, loosely overlapping, 3–15 mm, lobes 0–4, oblanceolate to elliptic, hairs abundant, spreading to ascending, (0.5–)1–3(–4) mm.
1–3;
blade well developed.
3–8(–10).
(1–)5–30(–150)-flowered, open, 0.5–14 cm diam.
20–120-flowered, (2–)4–14 cm diam., flowers mostly arranged in several to many tight glomerules of 5–10 flowers.
5–30 mm.
1–3(–12) mm.
6–12 mm diam.;
epicalyx bractlets 0(–3), lanceolate, 0.9–1.8 mm;
hypanthium turbinate or campanulate, 1.5–3(–5) × 1–3(–4) mm;
sepals 2–4(–5) mm, acute;
petals yellow or white, oblanceolate to elliptic or obovate, (1.6–)2–4 mm;
stamens 5, filaments 0.8–1.3 mm, anthers ± yellow, oblong to narrowly ovate, 0.6–1.5 mm;
carpels (2–)6–10(–13), atop a stipelike torus, styles 0.9–1.8 mm.
10–15 mm diam.;
epicalyx bractlets narrowly lanceolate to narrowly elliptic, (1.5–)2–2.5(–3) mm;
hypanthium campanulate to shallowly turbinate, 1.5–3 × 2.5–4.5(–5) mm, often nearly as deep as wide;
sepals sometimes purple-suffused, 3–5.5 mm, acute to acuminate;
petals white, broadly spatulate to broadly obovate or obcordate, 4–7 mm;
stamens 20, filaments filiform, 1.5–3 mm, anthers white to cream, 0.5–0.7 mm;
carpels 2–7, styles 2.5–4 mm.
greenish white to light tan, 1.2–2 mm, faintly rugose, ± carunculate.
brown, 2–3 mm.
= 28.
Ivesia arizonica
Ivesia sericoleuca
Varieties 2 (2 in the flora).
Because the epithet saxosa was retained for Potentilla saxosa upon transfer to Ivesia, a different epithet (arizonica) was needed when Purpusia was likewise transferred in the same publication (B. Ertter 1989). The correct name for this species in Potentilla is P. osterhoutii (A. Nelson) J. T. Howell, due to the existence of P. arizonica.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Of conservation concern.
Ivesia sericoleuca is known from valleys and flats in the northern Sierra Nevada. Many historic collections were identified and distributed as I. unguiculata, and circumscriptions prior to 1962 include I. aperta (hence reports from Nevada).
Hairs are usually dense in plants of Ivesia sericoleuca, such that the leaves, and occasionally the stems and branches, are silvery gray, especially in Sierra Valley and the Feather River drainage. Plants in the Truckee River drainage tend to be less hairy with redder stems, less glomerate inflorescences, shallower hypanthia, and more conspicuous glandularity.
As mentioned by J. T. Howell (1962), the chromosome count given for Ivesia sericoleuca by P. A. Munz (1959) most likely was based on a collection of I. aperta var. aperta. The chromosome count given here is instead based on Kruckeberg 3665, originally distributed as I. pickeringii.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Petals yellow; hypanthia campanulate. | var. arizonica |
1. Petals white; hypanthia turbinate. | var. saxosa |
CalFlora
WildflowerSearch
iNaturalist
USDA Plants Database
