Potentilla uliginosa
Potentilla pedersenii
Cunningham Marsh cinquefoil
not sheathed with marcescent whole leaves.
probably prostrate to decumbent, or ± ascending in supporting vegetation, 2.5–5.5 dm, lengths 1–2 times basal leaves.
ascending to nearly erect, 0.4–2 dm.
pinnate with distal leaflets ± confluent, 15–32 × 2–4 cm;
petiole 5–10(–15) cm, straight hairs absent or sparse to common, appressed, 0.5–1.5 mm, stiff, cottony hairs absent, glands absent or sparse;
primary lateral leaflets 6–10(–12) per side (irregularly paired), on distal ± 1/2 of leaf axis, loosely overlapping to proximally separate, largest ones cuneate to flabellate, 1.2–2.2 × 1–3 cm, ± whole margin unevenly incised 3/4 to nearly to midvein, ultimate segments (3–)5–10(–15), linear to narrowly oblanceolate, 5–17 × 1–2.5 mm, apical tufts less than 0.5 mm, surfaces green, not glaucous, straight hairs sparse (often glabrate adaxially), appressed, 0.5–1(–1.5) mm, stiff, cottony hairs absent, glands absent or sparse.
often both ternate and palmate or subpalmate on same plant, 2.5–4 cm;
petiole 1.5–2.5 cm, long hairs common to abundant, loosely appressed to ascending-spreading, 1–2 mm, weak to ± stiff, verrucose, crisped(/short) hairs absent or sparse to common, cottony hairs absent, glands sparse to common;
leaflets 3–5, proximalmost separated by 0–2 mm, central broadly elliptic to obovate, 1–1.5 × 0.5–0.9 cm, petiolules 1–2 mm, distal 2/3–3/4 of margin incised 1/2–3/4 to midvein, teeth (2–)3–4 per side, 4–6 mm, apical tufts ± 1 mm, abaxial surfaces grayish white to white, long hairs abundant (sometimes obscuring entire surface), cottony-crisped hairs abundant to dense, short hairs absent or obscured, glands sparse to common but usually obscured, adaxial grayish green to gray, long hairs sparse to abundant, 1–1.5(–2) mm, ± weak, short (short-crisped) hairs absent or sparse, rarely common, cottony hairs absent, glands absent or sparse, rarely common.
2.
0–2.
6–10-flowered, very openly cymose.
(1–)3–7-flowered, open, branch angle 30–50°.
1–6 cm, ± recurved in fruit.
1–2 cm, proximal to 4 cm.
epicalyx bractlets narrowly elliptic to oblong-ovate, 4–6 × 1–2.5 mm;
hypanthium 5–6 mm diam.;
sepals 4–7 mm, apex acute;
petals 6–10 × 5–8 mm;
filaments (1.5–)2–3 mm, anthers 0.7–1.2 mm;
carpels ca. 10, styles 2.5–3.5 mm.
epicalyx bractlets narrowly ovate to elliptic, 4–5 × 1–1.4 mm;
hypanthium 3–4 mm diam.;
sepals 4–6 mm, apex subacute to acute, glands sparse to common, usually not obscured;
petals pale yellow, usually not overlapping, 6–7 × 4–8 mm, distinctly longer than sepals;
filaments 1–2 mm, anthers ± 0.4 mm;
carpels 40–80, styles 0.8–0.9 mm.
2–2.6 mm, smooth, ± carunculate.
1.1–1.2 mm.
Potentilla uliginosa
Potentilla pedersenii
Of conservation concern.
Potentilla uliginosa is known only from a handful of historical collections from Cunningham Marsh, one of three wetlands in southern Sonoma County that harbor a suite of disjunct and regionally rare species (B. C. Johnston and B. Ertter 2010). Although previously included in P. hickmanii, P. uliginosa differs in having woodier caudices, longer stems and leaves, and more deeply incised leaflets occupying less of the leaf axis. Potentilla uliginosa is presumed extinct; however, a morphologically comparable collection of the P. millefolia complex from Josephine County, Oregon (Deer Creek, near Selma, 14 June 1929, Applegate 5735, UC), opens the possibility of additional undiscovered populations in the mountains of northwestern California.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Potentilla pedersenii and P. uschakovii account for the majority of arctic populations previously included in a broadly defined P. rubricaulis. The diagnostic morphological characters between the two species can be variable and overlapping; they are treated separately in part because of differences in presumed parental combinations. Whereas P. pulchella is the probable sect. Pensylvanicae parent for both species, the putative sect. Niveae parent for P. pedersenii is P. arenosa subsp. arenosa; that of P. uschakovii is P. subvahliana. Reflecting this parentage, P. pedersenii is distinguished by caudex branches with no marcescent whole leaves, verrucose long hairs on petioles, and inflorescences with usually several relatively small flowers. In contrast, P. uschakovii often has marcescent whole leaves sheathing the caudex branches, smooth long hairs on petioles, and one- or few-flowered inflorescences with mostly larger flowers. These generalities aside, there is much variation within both species, such that each island or population group may have its own features; it is probable that both P. pedersenii and P. uschakovii have evolved from multiple hybridization events.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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