Ragworts have small flower heads on long stalks appearing in a branched terminal cluster. The stem leaves are very deeply cleft. Prairie Ragwort is an erect native perennial that has a flower stem that can be from 6 to 24 inches high, covered with cobwebby looking hair.
Leaves: Prairie Ragwort has both basal and stem leaves. The long-stalked basal leaves are narrowly elliptic to lance shaped with a taper toward the stalk. They may have fine teeth, deeper crenations and sometimes lobes. Stalks often have hair. The stem leaves become progressively shorter, becoming quite tapered and then on the uppers they are pinnately irregularly lobed, and without stalks (sessile). Leaves will generally have fine hair resembling cobwebs.
The floral array is a branched cluster of 6 to 20+ flower heads with each head stalked. There are bracts on the cluster stem and the flower stem.
Flowers: The involucre (the flower head) is cylindric in shape, composed of two types of florets. There are 60+ bisexual disc florets of a deep yellow color with corolla tubes 2.5–3.5 mm long. These florets have 5 stamens tightly surrounding a single style, which is exerted from the floret throat when the floret opens. Disc florets open from the disc perimeter inward. The disc florets are surrounded by 8 to 10 yellow pistillate only ray florets with rays (laminae) that are slightly reflexed and 9–10 mm long. In all the head is 1/2 to 1 inch wide. The phyllaries around the outside of the flower head are light green with the tips sometimes a cyan color, and in a single series of 13 to 21. These are also covered with hair. The calyculi (involucre bracts below the phyllaries) are inconspicuous, but have purple tips.
Seeds: The cypselae (dry achene like seeds), are ribbed with minute hairs on the surface ribs (hirtellous) but sometimes without, 1.5 to 2.5 mm long, with fluffy white pappus for wind distribution. Seeds require at least 60 days of cold stratification plus light for germination.
Habitat: Prairie Ragwort grows from rhizomes in loamy soils with full sun and mesic to dry conditions and is usually found in old prairie areas. It spreads via the rhizomes and can become weedy. Some plants may lack rhizomes and have a fibrous root.
Names: In older reference works Prairie Ragwort was classified as Senecio plattensis. The genus Packera is now considered a segregate of Senecio. The name Packera is an honorary for Canadian plant systematist and contributor to Flora of North America, John Packer. The species name plattensis, refers to the Platte River, original collection area of the plant. The author names for the plant classification are: First to classify was '(Nutt.)' which refers to Thomas Nuttall (1786-1859) English botanist who lived and worked in America from 1808 to 1841. On his many expeditions he collected many species that had been originally collected by Lewis and Clark but lost by them on their return journey. He also collaborated with French botanist Francois Andre Michaux (1770-1855) in Michaux’s 3 volume North American Sylva.
Nuttall's work on this species was amended by 2 others: ‘W.A.Weber’ is for William Alfred Weber (b. 1918) professor at the U of Colorado, Boulder and former curator of the University of Colorado Museum Herbarium and ‘A.Löve’ is for Áskell Löve (1916-1994) Icelandic botanist, cofounder of the Flora-Europaea project and professor at various universities in North America. The older common names containing the word 'groundsel', according to Mrs. Grieve (Ref.#7) go back to Anglo-Saxon times and were derived from groundeswelge which meant 'ground-swallower' which referred to the rapid way in which some plants of the genus Senecio could spread. The older common name of Platte Groundsel, refers to its original discovery along the Platte River by Lewis and Clark.
Comparisons: Another similar ragwort is Golden Ragwort, Packera aurea, where the flowers have more golden centers and the stems and leaves are without hair. It grows in a more moist habitat.
Above: The stem is usually unbranched below the floral array. Stem leaves are few. 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 - The inflorescence has 6 to 20+ flower heads. 2nd photo - The phyllaries form a single series around the flower head, these showing purplish tips, and are covered with the cobwebby hair. Note the purple-tipped calyculi (involucre bracts below the phyllaries) are inconspicuous.
Below: Stem leaves are pinnately lobed and like the stem, have fine cobwebby hair.
Notes: Prairie Ragwort has not been listed on any previous Garden census. These photos are from 2012. The plant is well distributed in Minnesota, found in 2/3rds of the counties, most common in the western counties, but also found in the metro counties. It is one of six species of Packera in the state and is one of the three most common along with P. aurea (Golden Ragwort) and P. paupercula (Balsam Ragwort). Within The U.S. it is found from the Rocky Mountains eastward except for Texas and the coastal areas. In Canada it is known in Saskatchewan and Ontario.
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.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"