Cinquefoils of the Ottawa region

Menu

Now how do we recognize Potentilla from the other genera of the family? The flowers are distinguished by the calyx (the outer ring of small bracts that subtend the petals). The calyx has five lobes, but Potentilla is set apart from other genera (except Fragaria, the strawberry – and you know what that is!) by the five bracts that occur between the lobes so that the calyx appears to have 10 lobes. These bracts are collectively referred to as the epicalyx. The yellow, white, or red petals are five in number and are usually rounded at the apex but may be heart-shaped. The fruits are achenes (dry indehiscent fruits), which are borne on a dry, often hairy receptacle (a receptacle is the broadened end of the floral stalk).

In addition to these features, the leaves of Potentilla are compound. These are of two types: those that appear to radiate from the centre like the fingers of your hand (digitate or palmate) and those in which the leaflets are borne along a central stalk or rachis (pinnate). This is a very useful attribute because we can divide our local species into two groups based on it alone.

Cinquefoils are all very attractive, even if many of them are technically “weeds.” Jackson (1949) defined a weed as “any useless or troublesome plant, which occurs without intentional cultivation.” Accept this if you will. Do they have to have a use? Are they troublesome? Admittedly, some cinquefoils are, but many are not and are quite beautiful.

We have 12 native or adventive species in the region, and this article treats only of these. However, some other species are cultivated. In 1965, The Nepean Horticultural Society adopted Potentilla reptans as its official flower, but as far as I know the lemon coloured wild form does not occur in our area. Many hybrid types coloured yellow, cream, salmon, orange, pink, red, and white have been developed for gardens. A double flowered form, P. reptans pleniflora exists. Other species and cultivars include Potentilla arbuscula; P. atrosanguinea; and ‘Katherine Dykes,’ ‘Elizabeth,’ ‘Mandshurica,’ ‘Tangerine,’ ‘Moonlight’, and ‘Vilmoriniana’ varieties of Potentilla fruticosa. New hybrids are often being developed.

Some of the cinquefoils are apomictic. In broad terms, this means that some species have a problem with their sexual mechanism and no sexual fusing of gametes occurs (as opposed to the normal amphimictic condition where this does occur). Some have sexual forms, others may have both sexual and asexual forms. This situation may cause a blurring between the morphological characteristics that purport to separate them.

Fortunately, most of ours are sexual. An exception is P. argentea L. the Silvery Cinquefoil, Potentille argentée. This plant you probably already know. It is a common weed of unpaved driveways, roadsides, fields, yards, and waste ground. Silvery Cinquefoil has leaflets that are dark green above and bear silvery hairs below. They have attractive yellow flowers that persist well into autumn. But it is apomictic and the resulting variation in morphology has resulted in the recognition of as many as three species.

Apomixis is usually associated with polyploidy where plants occur with multiple complements of chromosomes. If 2n is the normal condition where n is the normal complement of chromosomes in the sexual cells (the pollen or the ovule), then 4n and even 6n types are found. Apomixis tends to occur in the higher polyploid condition. Morphologically, this situation results in variation in the number of teeth on the leaflet and whether or not the leaves are silvery below and green above. Other characteristics are influenced as well. Another apomictic species is P. norvegica L. which also shows considerable variation in morphology.

Now, it is tempting to consider P. fruticosa unique among our cinquefoils because of its shrubby habit, but another species, P. palustris, although a perennial herb, has a firm, almost woody base. Clearly, we cannot use the shrubby condition as a means of division. We had better separate them some other way. Let us now divided the species into two groups based on whether the leaflets are digitate or pinnate. (Those marked with an asterisk are considered to be weeds). The digitate group includes *P. norvegica, P. tridentata, P. simplex, *P. argentea, P. gracilis, *P. intermedia, and *P. recta. The pinnate group includes P. fruticosa, P. palustris, P. anserina, P. pensylvanica and P. arguta. So we have seven in the first group and five in the second – a convenient division.

*indicates non-native species

Key to the species of cinquefoil occurring in the Ottawa district

l. Leaves pinnate.
Go to 2

Leaves digitate.
Go to 6

2. Petals purple; plants woody at the base, herbaceous above. P. palustris

Petals yellow or white; plants not at all woody.
Go to 3

3. Flowers solitary in the axils of leaves or large bracts; plants with stolons (runners, if you like).
P. anserina

Flowers mostly in cymes (i.e., groups of 3), bracts small or none; not stoloniferous.
Go to 4

4. Shrub; achenes hairy.
P. fruticosa

Herb, sometimes somewhat woody at the base; achenes hairless.
Go to 5

5. Plants growing from the top of a thick taproot covered with old brown stipules; forming dense tufts; leaves with 7–15 oblong to oblanceolate leaflets about 3 cm long, these divided into linear segments, silky hairy on the back and with margins rolled inwards.
P. pensylvanica

Plants not in tufts; covered with long, silky, sticky hairs; leaflets 7–11, egg-shaped, coarsely toothed, downy along the veins, margins flat, not rolled inwards.
P. arguta

6. Leaflets 3.
Go to 7

Leaflets 5–7.
Go to 8

7. Plants tufted, erect with several stem leaves; stems branched above; leaflets ternate, toothed, deciduous; petals yellow, equal in length to the sepals or shorter.
P. norvegica

Plants sometimes forming mats; leaflets also ternate but toothed only at the tip, evergreen; petals white, longer than the sepals.
P. tridentata

8. Flowers solitary, with long slender stalks; plants at first erect, later ascending, stoloniferous or rooting at the tips, often forming mats.
P. simplex

Flowers in cymes (that is with one central flower and two laterals), but the pedicels very short or absent; plants erect without stolons and not rooting at the tips.
Go to 9

9. Leaflets silvery hairy beneath
Go to 10

Leaflets without silky hairs below.
Go to 11

10. Petals about equal to the sepals; leaves divided into pinnae but not to the base, with 3–5 divisions on each side; plants prostrate to ascending; common weed of waste places or along roadsides.
P. argentea

Petals longer than the sepals; leaves digitate, divided with numerous separate leaflets; western introduction.
P. gracilis

11. Hairs in the inflorescence appressed, not evidently long; inflorescence with very numerous flowers, these small about 1 cm in diameter; achenes smooth.
P. intermedia

Hairs divergent, white, very long; inflorescence with few flowers, these about 1.5 cm in diameter; achenes wrinkled.
P. recta

Notes on individual species

Drawing from USDA-NRCS PLANTS Database/Britton, N.L., and A. Brown. 1913.Illustrated flora of the northern states and Canada. Vol. 2: 258.

Potentilla anserina L.
Silverweed
Argentine, Richette
Common along the shores of the Ottawa and Rideau Rivers, this is a beautiful plant and I am always thrilled when I spot it. The plant is prostrate with creeping jointed runners or stolons bearing spreading hairs. The bright yellow flowers 1–2.5 cm in diameter and silvery foliage make it one of our most attractive plants. The pinnate leaves are all at the base of the plant; the leaflets oblong or nearly so with sharp teeth, green and hairless above and with silky, silvery leaves below. I would rather it be called Silverplant rather than Silverweed as it is not aggressive. Usually it is restricted to the shores of rivers in sand or in rock crevices, rarely in gravel fill, but I have seen it near railway tracks in the Nipigon area. Flowering throughout the summer. Can be grown in planters in the garden. The fruit is an achene (a dry indehiscent fruit) and is ovoid to almost round, thick.

Potentilla argentea L. *
Silvery Cinquefoil
Potentille argentée
Probably this is the most common species you can find. It is an introduced plant which flowers continuously from June to late August or September. You undoubtedly already know it, but if you don’t, look for a prostrate plant almost flattened against the ground or ascending to several decimeters tall in long grass or good soil. Normally it is a plant of dry poor soil such as unpaved laneways or rough ground. The leaves are digitate with 5 leaflets, each leaflet linear-oblanceolate or narrowly obovate in shape, 1.5–3 cm long, sometimes longer, silvery tomentose beneath, wedge-shaped at the base, bearing 2–4 oblong to linear teeth which have margins that are rolled inwards. The flowers are yellow, 7–10 mm wide the petals about equal in length to the sepals. The achenes are nearly smooth.

Drawing (left) and herbarium specimen (right) of P. argentea

Potentilla arguta Pursh
Tall Cinquefoil or Glandular Cinquefoil
Potentille âcre
This species is more common on the Quebec side of the Ottawa River where it is pretty well confined to the Gatineau Park escarpment; in Ontario it is at Westport, Merrickville, and the Shaw woodlot. The species is widely distributed across the continent in dry woods and on prairies.

The plant is erect, 3–10 dm tall and is sticky hairy. The leaves are pinnate, those at the base of the plant with long petioles; the leaflets 7–11 but fewer in the upper leaves, often alternate with minute, sharply toothed leaflets called folioles, hence the species name. The white to creamy flowers are nearly 2 cm in diameter, with ovate sepals, longer than the bracts and about as long as the petals. The stamens are clustered in 5 groups borne on a thick glandular disk. Achenes are obovoid, striate, about 1 mm long, pale brown. [photos of Potentilla arguta]

Drawing (left) and herbarium specimen (right) of P. arguta

Potentilla fruticosa L. [now Dasiphora fructicosa]
Shrubby Cinquefoil
Potentille frutescente
Easy to spot because it is a shrub about 2–4 feet tall. and has toothless pinnately compound leaves (by pinnately I mean the leaflets are borne along a rachis as I described above). It is found sparsely along the Ottawa River shores above Shirley Bay. Now this is either the same species or one of a group of species that we cultivate in our perennial borders. The species is very broad ranging, occurring throughout most of the north temperate zone. It is extremely variable, having large flowers and small flowers, yellow and white (var. veitchii) and even reddish flowers. Because of this variation, some botanists have recognized several species. It is this variation which makes it so attractive to horticulture. It also flowers for most of our season, flowers persisting until the end of September and even into October. For the garden it isn’t too choosy either, growing in both loam or soil of poor quality, in wet or dry situations, however it prefers a sunny location. You can grow it singly or form it into hedges. A disadvantage is that the stems are brittle and easily damaged. When it gets too old it becomes somewhat shabby. Then you can either replace them or prune them severely. Our native plant has yellow flowers (I’ve not seen white here but I have elsewhere).

The native shrub is 30–150 cm tall with bark that splits off in thin flakes The leaves have short petioles and are pinnately compound with 3–7 narrowly oblong toothless leaflets the upper ones often united at the base, these may be hairy on both sides or even silky below. Flowers are 2–3 cm wide, (some cultivated forms are much larger), solitary or with a few together at the tip of the branches, the petals are up to twice as long as the sepals, golden yellow but some cultivated forms are pure white. Bractlets between the sepals much narrower than the sepals. Ovary and achenes long hairy. This is a plant of wet meadows, but prefers calcareous places such as along the Ottawa River shore. It is occasionally seen in meadows or boggy areas. This species has been used medicinally. Some authors put it in a separate genus, Dasiphora.

Drawing from USDA-NRCS PLANTS Database/Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 262.

Herbarium specimen.

Potentilla gracilis Dougl.
Slender Cinquefoil
Potentille grêle
This is another one of those chiefly prairie species which is supposed to occur in the Ottawa valley. There is an old record from Hull (now Gatineau!) but because of the extensive urbanization that has and is taking place, it is unlikely you will come across it. Gleason & Cronquist refer to this species as P. flabelliformis Lehm., stating that the name P. gracilis is misapplied. Apparently there is a nomenclatural problem here that I do not wish to inflict on you.

Drawing from USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.

Herbarium specimen.

USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 254

Potentilla intermedia L. *
Downy Cinquefoil
Potentille intermédiaire
This is another weedy introduction from Europe. Apparently it is native to Russia and has become naturalized throughout Europe and eastern North America. An erect plant with numerous yellow flowers up to 1 cm across borne in dichotomous cymes (that is branching two ways). Leaflets are digitate with 5 leaflets in the lower part of the plant, often with 3 leaflets in the upper part, soft hairy and with a grayish appearance. Margins are strongly toothed, the lower part without teeth and tapering to the base The petals are about equal to the sepals. The achenes have many longitudinal ridges. Downy Cinquefoil is found along roadsides and in waste places as weeds tend to occupy such habitats.

Potentilla norvegica L. *
Rough Cinquefoil
Potentille de Norvège
Common weed throughout the region. But it is also a native circumboreal plant with a broad distribution which is obscured by the European introduced phase. Of course the name means Norwegian. Presumably Linnaeus described it from material from Norway, but a note attached to the specimen in his herbarium is a symbol for “eastern Asia.” Habitats include roadsides, waste places, fields and this sort of place. I planted some in my garden to examine them a little more closely next season. Rough Cinquefoil is a coarse plant 30–80 cm tall, with a thick branched stem, short hairy below but with spreading hairs above. Leaves digitate with 3 leaflets, these, elliptic to broadly obovate, about 3–10 cm long with rounded teeth. Flowers about 1 cm across, yellow, in cymes, with usually 20 stamens. The epicalyx members are ovate to lanceolate and about equal, the sepals united at the base in fruit and about 16 mm long. Petals are about equal to the sepals. The achenes are light brown, 1 mm long, flattened with longitudinal ridges.

Potentilla palustris L. [now Comarum palustre]
Marsh Cinquefoil, Comaret
Argentine rouge
Somewhat rare in this area. It is a circumboreal species found in marshes, along stream banks, moist areas. The striking thing about this species is that it has somewhat woody prostrate stems rooting in water and it has dark purple flowers. The reason for it being rare is that marshes are becoming rare in this area due to the expanding urban area and the filling in of many wet areas to construct dwellings and other forms of urbanization. This species is decumbent from a woody, rooting base. Leaves pinnate with long petioles; leaflets 3–7 coarsely toothed, 5–10 cm long, narrowly oblong to elliptic. Flowers about 2 cm across, 1 to many; petals purple, shorter than the broad calyx lobes. Epicalyx bracts narrower and shorter than the ovate calyx lobes. Style lateral on the glabrous achenes. Marsh Cinquefoil often forms extensive colonies in marshes and fens. Some authors put this species in a separate genus, Comarum because it differs in many characters from other cinquefoils.

Drawing from USDA-NRCS PLANTS Database/Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 257

Potentilla pensylvanica L.
Prairie Cinquefoil
Potentille de Pennsylvanie
Rare plant in this area. It is actually a western plant and the few records in the herbaria probably represent introductions. But a lot of changes have taken place with respect to urbanization and it may not exist at this point in time. The species is typically a northern plant found at James Bay, Thunder Bay, the Gaspé, Challenge? In case you go looking for it, the stems are erect, ascending or procumbent, 30–50 cm long, hairy exempt at the base. The leaves are distinctive, having 5–11 pinnately arranged leaflets deeply divided, progressively smaller towards the base. There is a stout taproot if you happen to dig the plant up. The flowers are borne in compact cymes only a few centimetres thick. Sepals are about equal in length to the bracts and equal or slightly shorter than the yellow petals. Style about 1 mm long, glandular and thick at the base. Flowering in summer.

Potentilla recta L.
Rough-fruited Cinquefoil
Potentille dressée
A common weed of fields but oddly enough some fields don’t seem to have them. It is a very handsome stiffly erect or ascending plant 40–80 cm tall with very large sulfur yellow flowers up to 2.5 cm in diameter. The epicalyx lobes are almost as long as the petals. The lower palmate leaves have 5–7 coarsely toothed narrowly oblanceolate leaflets, with strong divergent teeth. Achenes are striate. I have grown this species in my garden and to me it is a handsome subject, but not everyone would agree because it is considered a weed.

Drawing (left) and herbarium specimen (right) of P. recta. Inset at left of drawing is P. intermedia leaf.

Potentilla simplex Michx.
Common Cinquefoil
Potentille simple
The plant is initially erect and about 10 cm long, soon becoming prostrate, 40-69 cm long. and forming mats The stems arise from a short bulb-like rhizome. It roots at the tips. Internodes are long and the yellow flowers are borne singly from the leaf axils. Leaves are digitate with up to 5 leaflets. Leaflets are oblanceolate to elliptic, several cm long and toothed in the upper part. Flowers are yellow, 10–15 mm wide. I just love this plant – so much so that I transferred some to my garden where it forms a beautiful groundcover. Watch it though, as it is somewhat aggressive. It flowers in June and into July. [photos of Potentilla simplex]

Potentilla tridentata Ait. [now Sibaldiopsis tridentata]
Three-toothed Cinquefoil
Potentille tridentée
This is a beautiful little white-flowered cinquefoil. Down east it is quite common. I saw it at Longue Pointe de Mingan on the north shore of the St. Lawrence where it literally blanketed sandy open places. But it is a different story here. I first saw it on King Mountain in Gatineau Park where the late Erling Porsild showed me a colony on the rocks below the lookout. It is a bit precarious to go down to see it as it grows in rock crevices. But subsequently it has been found at several places in similar habitat along the escarpment. Easily recognized by the three-toothed leaflets and the white flowers. [photos of Potentilla tridentata]

All the other cinquefoils have either red (P. palustris) or yellow flowers. Now enjoy the cinquefoils. Do not regard them as weeds. There is an esthetic side to plant study and I believe these plants merit your admiration.

References

• Gleason, H.A., A. Cronquist. 1968. Illustrated Flora of the Northeast United States and Adjacent Canada. New York: Hafner.
• Jackson, B.D. 1960. A Glossary of Botanic Terms, with Their Derivation and Accent, 4th ed. London: Duckworth.
• Marie-Victorin, Frère. 1947. Flore laurentienne (reprint). Montréal: Les Frères de écoles chrétiennes. 63 p.
• Nepean Horticultural Society. 2007. 2007 Yearbook. Ottawa: Nepean Horticultural Society.
• Hay, Roy, and Patrick M. Synge. 1969. The Colour Dictionary of Garden Plants. New York: Bloomsbury.

Acknowledgements

I would like to thank Sandra Garland for her work on arranging the illustrations and for her interest in the project.

---