Montana Field Guide

PLANTS: Perennial forb that grows from a simple to branched caudex. Stems are singular to several, erect, and 20-50 cm tall. Stems have hispid hairs – long, straight, stiff, and perpendicular to the stem. Plants grow from a taproot with some shallow, spreading roots. Source: Rice in Sheley and Petroff 1999; Lesica et al. 2012

LEAVES: Leaves are arranged alternately. In outline leaf blades are somewhat round and 2-7 cm long. Leaves are palmately divided into 5 to 7 lanceolate, dentate leaflets with spreading hairs. Leaf size decreases upwards on stem. Petioles have hispid hairs which are perpendicular to the stalk. Basal leaves are similar. Source: Lesica et al. 2012

INFLORESCENCE: Yellow flowers are arranged in an open, flat-topped cyme (above the height of the leaves). 5 green sepals are lanceolate in shape, strongly veined, and 4–7 mm long. Bracteoles alternate with and appear similar to the sepals. 5 petals are light (sulphur) yellow, 6–10 mm long, longer than the sepals, and notched. Source: Lesica et al. 2012

Flowers in late spring through summer (Ertter and Reveal in FNA 2014).

Montana has at least 30 Potentilla or Cinquefoil species (Lesica et al. 2012). Readers are encouraged to learn their identifiable traits before implementing control on an unrecognized plant!

Sulphur Cinquefoil – Potentilla recta, exotic and Noxious:
* Fewer basal leaves with numerous stem leaves.
* Plants with long hairs perpendicular to their surface.
* Inflorescence ‘flat-topped’ and bright, light-yellow flowers.
* Taproot has short branches.
* Plants are more yellowish-green in comparison to other Potentilla plants.
* Leaflets are serrated about half-way to their mid-veins.
* Seeds with a net-like pattern on their coat.

Fanleaf Cinquefoil – Potentilla gracilis, native and desirable:
* Many basal leaves and relatively fewer stem leaves.
* Plants with short, spreading hairs.
* Underside of leaves have dense, woolly hairs.
* Plants are rhizomatous.
* Flowers are brighter/darker yellow.
* Leaves are green to gray-green.
* Leaflets are serrated more than half-way to their mid-veins.
* Seeds have a smooth coat.

Grasslands, meadows, pastures, and disturbed forests in the plains, valleys, and montane zones of Montana (Lesica et al. 2012).

VULNERABLE HABITATS [Adapted from Rice in Sheley and Petroff 1999]
Sulphur Cinquefoil has a wide ecological amplitude. In Montana it has been found in conifer, grassland, shrubland, and seasonal wetland systems. It has been found on most soil types; although not in pure silt. Sulphur Cinquefoil can colonize native plant communities without any apparent human disturbance. It has been found to get a hold into healthy, native grasslands by colonizing the ephemeral streams where soil is naturally disturbed (Andrea Pipp, MTNHP Botanist, personal observation).

DOMESTIC GRAZING
Sulphur Cinquefoil is primarily avoided by domestic animals. A study found that Sulphur Cinquefoil had trace-utilization on many sites used by livestock while Spotted Knapweed (Centaurea stoebe) had a 30% utilization.

POLLINATORS
The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus bifarius, Bombus fervidus, Bombus frigidus, Bombus rufocinctus, Bombus occidentalis, Bombus pensylvanicus, Bombus impatiens, and Bombus flavidus (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Colla et al. 2011, Koch and Strange 2012, Koch et al. 2012, Williams et al. 2014).

Plants reproduce by seed.

FRUITS
Fruits are achenes, ridged with thickened margins and about 1 mm long. Seeds are small, shaped like a comma (“,”), flattened, brownish-purple, and covered with a net-like pattern of veins (Rice in Sheley and Petroff 1999).

LIFE CYCLE [Adapted from Rice in Sheley and Petroff 1999]
Plants emerge in early spring. In Montana plants can produce basal leaves beginning in early March. Basal rosettes are fully formed in April. Plants often bolt in May and by June are blooming. With sufficient moisture flowering can occur into autumn. Seeds mature in July and disperse in August. Leaves senesce in August, but basal leaves can ‘green-up’ in response to late summer or early autumn rains. Growth continues until an extended freeze occurs.

Seeds remain viable in the soil for at least 3 years.

An integrated vegetative management approach provides the best long-term control, and requires that land-use objectives and a desired plant community be identified (Shelly et al. in Sheley and Petroff 1999). Once identified an integrated weed management strategy can be developed to promote a weed-resistant plant community and that serves other land-use objectives such as livestock forage, wildlife habitat, or recreation.

PREVENTION [Adapted from Rice in Sheley and Petroff 1999]
Preventing the establishment of Sulphur Cinquefoil can be accomplished by many practices:
* Learn to accurately identify Sulphur Cinquefoil in order to detect occurrences and know where to implement control methods.
* Prevent vehicles from driving through and animals from grazing within infested areas.
* Thoroughly wash the undercarriage of vehicles and wheels in a designated area before moving to uninfested areas.
* Frequently monitor for new plants, and when found implement effective control methods.
* Maintain proper grazing management that creates resilience to noxious weed invasion.
* Do not pick the flowers or transport plants. Where possible, contribute to or develop educational campaigns to help eradicate or reduce Sulphur Cinquefoil populations.

PHYSICAL and CULTURAL CONTROLS [Adapted from Rice in Sheley and Petroff 1999]

Hand-digging is effective for removing plants and eradicating small populations. As with any plants, long-sleeves and gloves should be worn to protect one’s skin. Hand-digging is easiest when soils are moist. Digging tools can easily be placed under the root-crown to remove the plant.

Mowing is not effective because the plants respond by developing heftier roots and more above ground stems.

CHEMICAL CONTROLS [Adapted from Rice in Sheley and Petroff 1999]
Herbicides can be effective, especially when properly integrated with intensive pasture management. The herbicide type and concentration, application time and method, environmental constraints, land use practices, local regulations, and other factors will determine its effectiveness and impact to non-target species. Strict adherence to application requirements defined on the herbicide label will reduce risks to human and environmental health. Consult your County Extension Agent and/or Weed District for information on herbicidal control. Chemical information is also available at Greenbook.

Picloram (0.25 pound acid equivalent (ae) per acre) applied in the spring to plants up to late bud stage or in the fall can provide several years of control. Residual activity of Picloram suppresses re-establishment from seed germination, but should only be used on upland sites and not around water.

2,4-D ester (1.0 pounds ae per acre) applied in the spring to plants at the rosette to bud stages will provide one year of good control. It may be better to use at sites near water.

Clopyralid is not effective on Sulphur Cinquefoil plants.

GRAZING CONTROLS [Adapted from Rice in Sheley and Petroff 1999]
Sulphur Cinquefoil is unpalatable to most livestock because of its high tannin content. On open range or in places with low stocking rates livestock have been found to eat the flowers of Spotted Knapweed (Centaurea stoebe) while ignoring Sulphur Cinquefoil in places where they co-exist. When Sulphur Cinquefoil is eaten it tends to be flowers or buds scattered across plants. Therefore, domestic grazing can favor the replacement of Spotted Knapweed, which is a short-lived perennial, with the longer-lived Sulphur Cinquefoil and the continual decline of native forbs and grasses.

Sheep and goats can eat Sulphur Cinquefoil, but is not shown to be very effective. Where animals are known to eat Sulphur Cinquefoil, they should be corralled for at least 3 days before moving into uninfested areas (Frost et al. 2013?).

BIOLOGICAL CONTROLS [Adapted from Rice in Sheley and Petroff 1999]
Using biological control organisms on Sulphur Cinquefoil has been problematic because of its genetically close relationship to strawberries (Fragaria spp.). Some root- and crown-boring insects found on Sulphur Cinquefoil plants in Montana were also found to be pests on strawberries (Rice in Sheley and Petroff 1999).

Useful Links:
Montana Invasive Species website
Montana Biological Weed Control Coordination Project
Montana Department of Agriculture - Noxious Weeds
Montana Weed Control Association
Montana Weed Control Association Contacts Webpage.
Montana Fish, Wildlife, and Parks - Noxious Weeds
Montana State University Integrated Pest Management Extension
Weed Publications at Montana State University Extension - MontGuides

Sulphur Cinquefoil has a wide ecological amplitude, is a long-lived perennial, and out-competes native plants. Therefore, it causes a loss in plant diversity over time.

Sulphur Cinquefoil is very competitive with other noxious weeds such as Spotted Knapweed, Yellow Starthistle (Centaurea solstitialis), and Leafy Spurge (Esula virgata) (Rice in Sheley and Petroff 1999).

Sulphur Cinquefoil does not provide forage for native or domestic ungulates (Rice in Sheley and Petroff 1999). It has a high concentration of phenolic tannins in its leaves and stems, which is assumed to be unpalatable (Rice in Sheley and Petroff 1999).