Ivesia argyrocoma
Ivesia pygmaea
silver-hair ivesia, silverhair mousetail
dwarf ivesia, dwarf mousetail
decumbent to erect, 0.3–1(–1.5) dm.
tightly cylindric, (0.5–)1–8(–12) cm; sheathing base usually ± strigose abaxially;
petiole 0.5–4 cm, hairs 0.2–1 mm;
leaflets 10–15(–20) per side, 0.5–4(–5) mm, sparsely to moderately short-villous, densely glandular, lobes 3–6(–8), oblanceolate to narrowly oblong or oval, apex setose.
(0–)1, not paired.
(1–)5–10-flowered, 0.8–3 cm diam.;
glomerules usually 1.
1.5–8(–10) mm.
9–11 mm diam.;
epicalyx bractlets elliptic to oblong, 1.2–2 mm;
hypanthium shallowly cupulate, 1–2 × 2.5–5(–7) mm;
sepals 2–3.5 mm, bluntly acute;
petals golden yellow, broadly oblanceolate to spatulate or broadly obovate, (2–)2.5–3.5(–4) mm;
stamens 10, filaments 0.6–1.8 mm, anthers yellow, 0.6–0.8 mm;
carpels 10–30, styles 0.9–1.3 mm.
greenish tan to light brown, 1.2–1.5 mm.
Ivesia argyrocoma
Ivesia pygmaea
Varieties 2 (1 in the flora).
Plants from the central Sierra San Pedro Mártir in northern Baja California belong to var. moranii Ertter & Reveal, which may be distinguished by its compact stature (to 0.5 dm), densely villous basal stipules 2–4 mm, decumbent stems 2–7 cm that are stipitate-glandular under the villous indumentum, and solitary, loosely congested cyme. The petals are oblanceolate to narrowly obovate and 2.5–3.5 mm. The grayish, faintly mottled achenes are 1.3–2 mm.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Ivesia pygmaea is known only from the southern Sierra Nevada in California, where it overlaps the range of I. lycopodioides var. megalopetala. Stamen number is the only unequivocal way to distinguish between the two, though I. pygmaea is also more generally setose with somewhat shallower hypanthia. It is also more likely to have much-branched caudices and can form mats in rocky sites. Larger plants with relatively open cymes have sometime been segregated as I. chaetophora; this probably represents ecological and phenotypic plasticity.
Early reports of Ivesia pygmaea from Nevada are based on P. A. Rydberg’s (1898) mistaken understanding of the type locality, which is actually in Tulare County, California. A reported occurrence from the northern Sierra Nevada in Nevada (J. T. Kartesz 1987) is presumably based on the same source as the unconfirmed report of I. lycopodioides from the same locality (D. D. Keck 1938).
The correct name for this species if treated as Potentilla is P. nubigena Greene; P. decipiens Greene is a later homonym and illegitimate.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
CalFlora
WildflowerSearch
iNaturalist
USDA Plants Database
