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Comarum palustre

comaret des marais, marsh potentilla, marsh-cinquefoil, purple cinquefoil, purple marsh-locks

Habit Herbs, perennial, rarely annual or biennial, shrubs, or subshrubs; unarmed.
Stems

1–10(–18) dm.

Leaves

petiole 5–10(–15) cm;

leaflets usually abaxially glaucous, adaxially green, sometimes silvery-silky, often aging reddish, 1.5–10(–12) × (0.8–)1–5 cm.

alternate, rarely opposite, pinnately (palmately) compound (simple in Alchemilla, Aphanes, and Chamaerhodos);

stipules persistent (absent in Chamaerhodos), adnate to petiole;

venation pinnate or palmate.

Pedicels

5–25(–30) mm.

Flowers

epicalyx bractlets narrowly lanceolate to lanceolate, 2–7(–9) mm, usually equal to or shorter than sepals;

sepals greenish purple adaxially, (5–)7–12(–14) mm, apex acuminate;

petals 2.5–6(–8) mm;

anthers dark purple, 0.8–1.2 mm, connectives thickened, greenish purple to purple;

styles 0.9–2 mm.

perianth and androecium perigynous;

epicalyx bractlets present, sometimes absent;

hypanthium usually patelliform, cupulate, or campanulate, sometimes turbinate, saucer-shaped, flat-bottomed, or subglobose to ellipsoid or ovoid;

torus flat to conic or turbinate, enlarged (absent or reduced in Alchemilla, Aphanes, and Chamaerhodos);

carpels 1–260, styles basal or lateral to subterminal, distinct;

ovules 1(or 2), basal.

Fruits

aggregated achenes (achenes in Alchemilla and Aphanes);

torus sometimes fleshy;

styles deciduous or persistent, not elongate.

2n

= 28, (35)36, 42, (60, 62, 63)64.

Comarum palustre

Rosaceae tribe Potentilleae

Phenology Flowering summer.
Habitat Shallow, often sphagnum-dominated ponds, bogs, wet meadows, marshes, stream banks, and lake margins, mainly in boreal and low arctic habitats in the north, subalpine to alpine sites in the south
Elevation 0–3100 m (0–10200 ft)
Distribution
from FNA
AK; CA; CO; CT; IA; ID; IL; IN; MA; ME; MI; MN; MT; ND; NH; NJ; NY; OH; OR; PA; UT; VT; WA; WI; WY; AB; BC; MB; NB; NL; NS; NT; NU; ON; PE; QC; SK; YT; SPM; Greenland; Eurasia
[WildflowerSearch map]
[BONAP county map]
North America; Mexico; Central America; South America; West Indies; Bermuda; Eurasia; Africa; Atlantic Islands; Pacific Islands; Australia
Discussion

Comarum palustre is circumboreal; it occurs in a broad band across the northernmost United States and Canada as far north as the low arctic. Disjunct populations occur well to the north, as on Baffin and Victoria islands, and in the south, as in Gunnison County, Colorado, and the Uinta Mountains of Utah. Appropriate habitats are uncommon and geographically restricted in the southern part of the range, for example, in Idaho, Montana, and North Dakota.

Comarum palustre is sometimes divided into subspecies, varieties, and/or forms on the basis of vestiture, leaflet dimensions, and flower number (for example, M. L. Fernald and B. H. Long 1914; N. N. Tzvelev 2007). Because there is no existing consensus, and a global evaluation of the situation is beyond the scope of this work, no infraspecific taxa are recognized here. Within North America, northern populations tend to have broader leaflets and inflorescences composed of one to relatively few flowers with relatively short sepals and petals, but these differences are not consistent; similar plants occur in subalpine settings in the mountains well to the south. Chromosome numbers also vary, apparently not correlated with morphology or geography; some populations occasionally include individuals of different disploid and polyploid levels.

Horizontal stems were used occasionally by Native Americans as a medicinal aid in the treatment of dysentery and stomach cramps (D. E. Moerman 1998). Aquatic birds in particular eat the leaves and achenes.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Genera 14–22, species ca. 860 (14 genera, 189 species, including 1 hybrid, in the flora area).

The base chromosome number for Potentilleae is mostly x = 7 (8 in Alchemilla and Aphanes; 14 in Comarum).

Variation in the number of genera recognized in Potentilleae is due to differences in generic delimitation between D. Potter et al. (2007) and the authors of Potentilla and segregates here (see 9. Ivesia and 8. Potentilla for discussion). In the former, Duchesnea, Horkelia, Horkeliella, and Ivesia are included within Potentilla. Likewise, Aphanes is included within Alchemilla by Potter et al. while it is kept distinct here.

Potentilla and its segregates and Fragaria are host to Phragmidium rusts, but not the other genera of the tribe.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Shrubs; leaf lobe margins entire; achenes hirsute.
Dasiphora
1. Herbs, perennial, sometimes annual or biennial, or subshrubs; leaf lobe margins or apices ± toothed, sometimes entire; achenes glabrous (sometimes ± hairy)
→ 2
2. Petals 0, sepals 4; achenes 1, enclosed in dry, urceolate or subglobose to ellipsoid or ovoid hypanthia
→ 3
2. Petals and sepals usually 5; achenes 1–260, usually aggregated (sometimes on elongating tori), usually in (± open) patelliform, cupulate, campanulate, or turbinate hypanthia (not enclosed in dry hypanthium)
→ 4
3. Herbs perennial; leaves basal, blades reniform to orbiculate, palmately lobed, sometimes palmately compound; stamens 4.
Alchemilla
3. Herbs annual; leaves cauline, blades cuneate, deeply divided into segments, each lobed; stamen 1(or 2).
Aphanes
4. Leaves all or mostly basal or proximal (if cauline, deeply pinnatifid), ternate or 2–4-ternate (sometimes simple and coarsely toothed apically in Sibbaldia)
→ 5
4. Leaves basal or cauline, the latter usually reduced distally, odd-pinnate to palmate, rarely ternate or ± bipinnate
→ 9
5. Tori becoming red and fleshy in fruit; leaf margins serrate to crenate
→ 6
5. Tori hemispheric (not enlarged or fleshy) in fruit or absent; leaf margins entire or (2–)3(–5)-toothed apically
→ 7
6. Leaves ± doubly serrate or crenate; stolons leafy; inflorescences: flowers solitary, axillary at stolon nodes; petals yellow.
Duchesnea
6. Leaves serrate to crenate; stolons not leafy; inflorescences 1–10-flowered, cymes, axillary from leaf rosettes; petals usually white.
Fragaria
7. Leaves pinnately compound or simple and deeply pinnatifid, margins entire, stipules absent.
Chamaerhodos
7. Leaves ternate, margins toothed apically, stipules persistent
→ 8
8. Petals ± yellow; stamens 5.
Sibbaldia
8. Petals usually white; stamens 20(–30).
Sibbaldiopsis
9. Petals deep red to purple, rarely pink, shorter than sepals; tori enlarged and spongy at maturity; horizontal stems sometimes floating, wetland habitats.
Comarum
9. Petals yellow to white, rarely pink or red (then equal to or longer than sepals); tori not enlarged and spongy at maturity; stems erect to decumbent, not horizontal or floating even if in wetlands
→ 10
10. Anthers dehiscing by continuous marginal slit (with a single theca); styles sub-basal.
Drymocallis
10. Anthers dehiscing longitudinally; styles subterminal to lateral
→ 11
11. Hypanthium patelliform to campanulate or cupulate to turbinate (not flat-bottomed); filaments not forming tube; petals white to yellow, sometimes reddish or pink tinged
→ 12
11. Hypanthium ± cupulate or bluntly campanulate and flat-bottomed; filaments forming tube; petals usually white, sometimes pink-tinged, rose-veined, or cream
→ 13
12. Plants not aromatic; leaves ± cordate or reniform to narrowly elliptic in outline, leaflets 3–15(–41); petals oblanceolate or obovate to obcordate to nearly round, rarely elliptic; carpels 3–260.
Potentilla
12. Plants often aromatic; leaves planar to cylindric, leaflets (3–)7–161; petals linear or narrowly oblanceolate to obovate, sometimes obcordate; carpels 1–20(–40).
Ivesia
13. Stamens 10; leaflets (3–)5–41.
Horkelia
13. Stamens 20; leaflets 30–70.
Horkeliella
Source FNA vol. 9, p. 301. FNA vol. 9, p. 119. Author: Luc Brouillet.
Parent taxa Rosaceae > subfam. Rosoideae > tribe Potentilleae > Comarum Rosaceae > subfam. Rosoideae
Subordinate taxa
Alchemilla, Aphanes, Chamaerhodos, Comarum, Dasiphora, Drymocallis, Duchesnea, Fragaria, Horkelia, Horkeliella, Ivesia, Potentilla, Sibbaldia, Sibbaldiopsis
Synonyms C. palustre subsp. angustifolium, C. palustre subsp. arcticum, Fragaria palustris, Potentilla palustris, P. palustris var. parvifolia, P. palustris var. villosa
Name authority Linnaeus: Sp. Pl. 1: 502. (1753) Sweet: Brit. Fl. Gard. 2: sub plate 124. (1825)
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