Potentilla thurberi

A. Gray

Pl. Nov. Thurb., 318. 1854.

Common names: Scarlet or Thurber’s cinquefoil
Treatment appears in FNA Volume 9. Treatment on page 149. Mentioned on page 148.

Stems (2–) 3–7 (–10) dm. Basal leaves palmate, (2–) 4–15 (–30) cm; petiole (2–) 3–10 (–25) cm, long hairs sparse to common, spreading, 1–3.5 mm, weak, glands sparse to abundant, sometimes absent; leaflets 5 (–7), at tip of leaf axis, central one (1–) 2–6 (–8) × (0.5–) 1–2.5 (–4) cm, petiolules 0 (–10) mm, distal 3/4 to whole margin incised 1/5–1/4 to midvein, teeth (4–) 7–15 (–19) per side (sometimes secondarily toothed), (1–) 2–3 (–5) mm, teeth apex acute to ± obtuse, surfaces slightly to strongly dissimilar, abaxial pale green to white, straight hairs sparse to abundant, often dense on veins, 0.5–3 mm, cottony hairs absent or sparse to dense, glands ± sparse or absent, sometimes obscured, adaxial green, straight hairs sparse to abundant, 0.2–1 mm, cottony hairs absent, glands ± sparse or absent. Cauline leaves: stipules usually toothed, sometimes entire. Inflorescences (4–) 10–35-flowered. Pedicels 0.5–4 cm. Flowers: epicalyx bractlets narrowly to broadly lanceolate-elliptic (rarely toothed or lobed), 4–9 (–14) × (1–) 1.5–2 mm; sepals 4–10 (–15) mm, apex acute to acuminate; petals ± dark reddish throughout, (3.5–) 6–10 × 6–10 mm; filaments 1.5–3 mm, anthers 0.8–1 mm; carpels 30–70, styles 2.5–3.5 mm. Achenes 1.5 mm, ± rugose.

Discussion

Varieties 2 (2 in the flora).

The abaxially white-cottony leaflets of var. atrorubens usually make it easily distinguished from var. thurberi, which lacks cottony hairs and is usually less hairy in general. The two varieties sometimes occur together and intermediates between the extremes are common.

The degree of glandularity and the lengths of the central leaflets are greater in the southern populations of both varieties. The glands are less widely distributed on the plants northward and are fewer in northern Arizona and New Mexico. Leaflets are shorter and broader north of Graham County, Arizona, and Otero County, New Mexico.

Selected References

None.

Key

1 Leaflets pale green abaxially, cottony hairs absent. Potentilla thurberi var. thurberi
1 Leaflets ± white to white abaxially, cottony hairs sparse to dense. Potentilla thurberi var. atrorubens

"dm" is not declared as a valid unit of measurement for this property.

... more about "Potentilla thurberi"
pale green +  and white +
green +  and white +
0.08 cm0.8 mm <br />8.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Barbara Ertter +  and James L. Reveal +
A. Gray +
15 cm150 mm <br />0.15 m <br /> (30 cm300 mm <br />0.3 m <br />) +
4 cm40 mm <br />0.04 m <br /> (15 cm150 mm <br />0.15 m <br />) +
Rubrae +
25 cm250 mm <br />0.25 m <br /> (30 cm300 mm <br />0.3 m <br />) +
less cordate or reniform +  and narrowly elliptic +
0.5 cm5 mm <br />0.005 m <br /> (25 cm250 mm <br />0.25 m <br />) +
reduced +
free +  and distinct +
hairy +  and glabrous +
6 cm60 mm <br />0.06 m <br /> (8 cm80 mm <br />0.08 m <br />) +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
2 cm20 mm <br />0.02 m <br /> (6 cm60 mm <br />0.06 m <br />) +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Scarlet or Thurber’s cinquefoil +
Ariz. +, N.Mex. +  and nw Mexico +
not +  and aggregated +
0.9 cm9 mm <br />0.009 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (2 cm20 mm <br />0.02 m <br />) +
unisexual +  and bisexual +
not +  and aggregated +
deciduous +
on style scar +, hairy +  and glabrous +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.26 cm2.6 mm <br />0.0026 m <br />) +
crisped +
stoloniferous +  and short-rhizomatous +
straight +
sparse +  and abundant +
crisped +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
0.7 cm7 mm <br />0.007 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.4 cm4 mm <br />0.004 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
(4-)10-35-flowered +
crassinucellate +
bipinnate +, odd-pinnate +, subpalmate +, palmate +  and ternate +
opposite +  and alternate +
marcescent +
well-developed +
persistent +
cauline +  and basal +
reduced +
not +  and overlapping +
oblong +  and elliptic or obovate +
linear +  and oblanceolate +
palmate +  and pinnate +
inferior +  and superior +
clustered +, biseriate +  and superposed +
0.5 cm5 mm <br />0.005 m <br /> (4 cm40 mm <br />0.04 m <br />) +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
free +  and distinct +
0.6 cm6 mm <br />0.006 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.5 cm5 mm <br />0.005 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.6 cm6 mm <br />0.006 m <br /> (1 cm10 mm <br />0.01 m <br />) +
10 cm100 mm <br />0.1 m <br /> (25 cm250 mm <br />0.25 m <br />) +
3 cm30 mm <br />0.03 m <br /> (10 cm100 mm <br />0.1 m <br />) +
0 cm0 mm <br />0 m <br /> (1 cm10 mm <br />0.01 m <br />) +
1/5 +  and 1/4 +
0 cm0 mm <br />0 m <br /> (?) +
adnate +, free +, connate +  and distinct +
palmate +  and more or less subpalmate +
15 cm150 mm <br />0.15 m <br /> (30 cm300 mm <br />0.3 m <br />) +
4 cm40 mm <br />0.04 m <br /> (15 cm150 mm <br />0.15 m <br />) +
Pl. Nov. Thurb., +
not arillate +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
persistent +
free +  and distinct +
erect +  and spreading +
lanceolate +  and broadly ovate or deltate +
0.4 cm4 mm <br />0.004 m <br /> (1 cm10 mm <br />0.01 m <br />) +
free +  and distinct +
not rooting +
reddish +  and green +
(2-)3-5 times basal leaves +
ascending +  and nearly erect +
1 +  and many +
not flagelliform +
palmate +  and pinnate +
deciduous +
distinct +
subapical +
papillate-swollen +  and tapered-filiform +
rough-thickened +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
Potentilla sect. Haematochrus +  and Haematochrus +
not fleshy-thickened +
Potentilla thurberi +
Potentilla sect. Rubrae +
species +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
7 +  and 15 +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
inconspicuous +
enlarged +
biennial +, annual +  and perennial +
herb +  and matted +