Curlycup Gumweed is an erect biennial or short-lived perennial growing to 40 inches high on smooth stems that branch at the top. It is an introduced, naturalized plant to our area. The first year the plant forms a rosette with the stem forming the second year, but some plants may flower the first year. Stems are smooth, angled and sometimes reddish.
The leaves are alternate but of various shapes. They can be oblong, linear, lanceolate to ovate, up to 2-1/2 inches long, from 2 to 5x longer than wide and are dotted with resinous glands. Surfaces are without hair, leaf margins are usually coarsely toothed but may be entire. Middle stem and upper leaves clasp the stem.
The floral array is composed of branched almost flat-topped clusters (corymbiform arrays) of flower heads at the top of stems.
Individual flower heads are 1 to over 2 inches wide with 25 to 40 yellow ray florets surrounding a central disc of yellow disc florets. The ray florets are pistillate and fertile with rays 1/2 to 9/16 inch long. The disc florets can number over 100 and are usually bisexual and fertile, although sometimes only the outer ones are fertile and the inner are functionally staminate only. The fertile disc florets have yellow corollas, 5 stamens whose filaments surround a single style. Beneath the flower head there are 5 to 6 series of phyllaries (Bracts) that are reflexed to spreading with tips looped or hooked. These are linear to lanceolate in shape, scaly, and usually very resinous. The young flowers and buds are covered with a thick milky exuded substance which has a balsamic smell and a bitter taste.
Seed: Fertile flowers produce a cypsela, 1.5 to 4.5 mm long, with faces that can vary from smooth to striate to or furrowed. The color varies from white to brown or gray. Fluffy pappus falls away early leaving only 2 to 3 awns, 2.5–5.5 mm long.
Habitat: Curlycup Gumweed is found in disturbed areas, plains, along streams and frequently today along roadsides. It accepts all types of soils, moderate moisture to dry, and full sun. It is tap-rooted, growing from a short vertical rhizome with extensive deep roots.
Names: The genus, Grindelia, is an honorary named for David Grindel (1776-1836), a Latvian pharmacologist and doctor, who is considered the first natural scientist. The species, squarrosa, which means 'spreading' or 'recurved' is applied to plants where the bracts or phyllaries are spreading to recurved. The author names for the plant classification are: First to classify was ‘Pursh’ which refers to Frederick Traugott Pursh (1774-1820) German-American botanist who wrote A Systematic Arrangement and Description of the Plants of North America, and was the botanist who catalogued and described the plants brought back by the exploring expedition of Lewis and Clark. His work was amended by ‘Dunal’ which refers to Michel Félix Dunal (1789 - 1856), French botanist, chair of the Dept. of Natural History at the University of Montpellier. His main research and writing was on the Nightshades in the genus Solanum.
Comparisons. This species is similar to G. hirsutula, the Hairy Gumweed where the stems are hairy, the leaves have few if any glands and the flower heads are not resinous.
Above: The floral array is a loose to dense array of flat-topped clusters. Drawing from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - Buds are covered with a thick milk exude with a balsamic odor. 2nd photo - 25 to 40 yellow ray florets surround the central disc florets.
Below: 1st photo - Phyllaries are in 5 or 6 series with spreading hooked or looped tips, all very resinous. 2nd photo Seeds are a dry cypsela with 2 to 3 awns but no fully pappus as it falls away very early.
Below: 1st photo - The plant has many clusters of flower heads at the tops of stems. 2nd photo - Leaves are of various shapes, usually linear with toothed edges, one main vein, resinous glands and stem leaves (3rd photo) clasp the smooth angled stem.
Notes: Curlycup Gumweed was present in Glenwood Park, which surrounded the Garden, but was not present in the Garden, so Eloise Butler transplanted some from Glenwood Park to the Garden on June 15, 1910 and again on Sept. 25, 1913 she brought in plants from 4748 Chicago Ave., Minneapolis (this is the address where, at this time period, she roomed with a friend). One additional plant was added on June 25, 1914. Martha Crone noted it in bloom in 1938 and it was still present in the Garden at the time of her 1951 Garden Census, but was gone by the time of the 1986 census.
Curlycup Gumweed is found throughout North America except the very far north, the Canadian Maritime Provinces and the states of the SW U.S. gulf coast. It is thought to be native to the Great Plains and Rocky Mountain area and then spread to the rest where it has naturalized. Within Minnesota it is found in about half of the counties widely scattered throughout the state as might be expected of a plant that naturalized. This includes most of the metro counties. The only other Grindelia recognized in the state is G. hirsutula, but that is less frequently found.
Eloise Butler wrote: "Not many years ago the gum plant, was not to be found within the limits of Minneapolis. It is common on the great plains, and it has spread from the western part of the state until it is now a common weed by sandy roadsides and in vacant lots, and one against which our gardeners and famers wage battle. Nevertheless, it is an attractive plant with its profuse, pure yellow flower heads resembling sunflowers and its lettuce-green leaves."
"We are glad, moreover, to learn that [it] is of some use, as a specific for ivy poisoning. But why is it named gum plant? Not that it furnishes a delectable wad for the ruminating folk, but because under the flower clusters a mass of sticky, resinous matter is exuded to keep out from the blossoms the crawling insect tribes that are unable to do the work of pollination. It is unnecessary to glue the flower heads to the herbarium sheets, for they provide their own mucilage." Published Sept. 3, 1911, Minneapolis Sunday Tribune - entire article.
Uses: Curly-cup Gumweed is unpalatable to browsing mammals due to the presence of tannins, oils, resins and alkaloids. However for human medicinal use, the plant has been found useful in the first part of the 20th century. Moore (Ref. #30) states that the parts used included the buds and flowering heads when first in bloom and the leaves before flowering. The dried leaves will make a tea for bronchitis or as an expectorant. The tea is aromatic but bitter. Dried flowers are used for a tincture to treat bladder infections. The gummy buds and flowers can be chewed as chewing gum. Hutchins (Ref.#12) reports that Native Americans in the Rocky Mountain area used extracts of the plant as an antidote for poison oak and poison ivy. The plant is no longer listed in U.S. Pharmacopoeia.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"