Ivesia utahensis
Ivesia pygmaea
Utah ivesia, Utah mousetail
dwarf ivesia, dwarf mousetail
prostrate to ascending, 0.5–1.5(–2) dm.
decumbent to erect, 0.3–1(–1.5) dm.
± tightly cylindric, 2–7(–9) cm; sheathing base glabrous abaxially;
petiole 0.5–2 cm, hairs 0.5–1 mm;
leaflets 15–20 per side, 2–4 mm, glabrate or sparsely short-hirsute, sparsely to densely glandular, lobes (2–)3–8, narrowly oblanceolate to obovate, apex not setose.
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.
(0–)1, not paired.
(5–)10–30-flowered, 1–2.5(–5) cm diam.;
glomerules 1–few.
(1–)5–10-flowered, 0.8–3 cm diam.;
glomerules usually 1.
1–7 mm.
1.5–8(–10) mm.
7–9 mm diam.;
epicalyx bractlets narrowly oblong to oval, 0.8–2 mm;
hypanthium shallowly cupulate, (1–)1.5–2 × 2.5–3.5 mm;
sepals (1.8–)2–3 mm, acute;
petals white, sometimes pink-tinged, oblanceolate to spatulate, 1.8–3 mm;
stamens 5, filaments 1.3–1.8 mm, anthers orangish to reddish brown, 0.4–0.6 mm;
carpels (1–)2–4, styles 1.5–2 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.
yellowish green to light tan or gray-brown, 1.7–1.9 mm.
greenish tan to light brown, 1.2–1.5 mm.
Ivesia utahensis
Ivesia pygmaea
Of conservation concern.
Ivesia utahensis is known from the Wasatch and adjacent Uinta Mountains in northern Utah. The species stands as the white-petaled counterpart to the yellow-petaled Sierran I. lycopodioides, possibly indicating a common ancestral stock that was once more continuous across the Great Basin.
(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.)
WildflowerSearch
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USDA Plants Database
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