Curlycup gumweed (Grindelia squarrosa L.)
Curlycup gumweed is a coarse biennial to weak perennial from 30 to 90 cm (one to three feet) tall. Curlycup gumweed is a herbaceous plant that belongs to the sunflower family.
Stems: Many smooth stems grow from a deep tap root.
Roots: Stubbendieck et al, 1989, report the plant as having an underground rhizome system. Root systems can reach depths of two meters (6.5 feet).
Leaves: The dark green leaves are thick, oblanceolate (narrow ellipse or lens shaped) from one to four cm long and gummy to the touch. The leaf margins are closely toothed.
Flowers: Its showy yellow flowers are surrounded by numerous bracts at the base. The curved tips of these bracts are covered by a gum-like resin. Flowering occurs from July through September. Growth habit is erect with many branches coming off a single stem.
Seeds: Seeds are achenes (like a sunflower seed).
Reproduction
By seeds and underground stems.
Historical use
In early times, curlycup gumweed had medicinal uses. Spanish New Mexicans would drink an extract made from boiling three flower buds three times in three pints of water until only one pint was left. They would drink a glassful three times daily for kidney problems. Others used gumweed extracts to treat a wide range of ailments from skin troubles to rheumatic pains.
Curlycup gumweed was used by the North American Indian people for various purposes:
- Gummy secretions were used to relieve asthma, bronchitis and colic;
- A boiled extract of leaves and/or flowering tops relieved saddle sores and raw skin;
- It was consumed as tea in an attempt to cure tuberculosis;
- Again as tea, to relieve coughs, as an expectorant, and treat dizziness;
- The crushed flowers were used to make poultices for treating poison ivy;
- The sticky sap was chewed as gum; and
- Leafless stems would be used as brooms.
In modern medicine, extracts of the leaves and buds are used to treat whooping cough and asthma.
Location
A common increaser throughout the entire non-wooded areas from western Ontario to British Columbia. Sparse populations are found in Ontario and Quebec. It has been increasing in Saskatchewan, especially on the drier areas of saline flats and slough margins. Overgrazing of these types of areas definitely encourages gumweed. Plant populations increase under drought conditions.
Concerns
Because of its resinous coating, curlycup gumweed is not palatable to either livestock or big game. Some upland game birds will utilize the seeds. In dense infestations of curlycup gumweed, livestock are reluctant to graze between the plants, leaving some grasses ungrazed. Although, Sheep will nip off a few flowers when hard pressed.
Gumweeds can have toxic properties which to a large extent depend on the soil where they grow. This is especially true for curlycup gumweed. When excessive selenium is absorbed, the plant becomes poisonous.
Control
Gumweed does not tolerate frequent disturbance, and is therefore rarely a problem in annual crops.
No herbicides appear to give consistent results. Herbicides containing 2,4-D or MCPA are labelled to provide top-growth control at 560 to 840 g per ha (8 to 12 oz. per acre) of active ingredient. The Canadian label for Restore (aminopyralid + 2,4-D) states that the product will provide top-growth control only, and the label for the equivalent product in the United States claims control at the same rate.
Good grazing management will prevent populations of gumweed from increasing. Avoid overgrazing sloughs and slough-like areas.