Geum triflorum, commonly known as prairie smoke, old man's whiskers, or three-flowered avens, is a spring-blooming perennial herbaceous plant of the Rosaceae family. It is a hemiboreal continental climate species that is widespread in colder and drier environments of western North America, although it does occur in isolated populations as far east as New York and Ontario. It is particularly known for the long feathery plumes on the seed heads that have inspired many of the regional common names and aid in wind dispersal of its seeds.
Description
Geum triflorum is a perennial herb with short, spreading rhizomes, which form colonies of stemless rosettes. The roots are fiberous and have a sassafras-like flavor. The leaves grow from a caudex and are 4–30 cm (1.6–12 in) long. They are divided into leaflets with deep divisions that makes the leaves resemble the leaves of a fern. The leaflets are arranged pinnately along a common leaf stem with smaller leaflets mixed in with 7–18 larger ones and single larger leaflet at the end of the leaf. The leaves are covered with extremely small downy hairs. Early in the spring, the leaves often lie flat to the ground and are in poor condition, but they soon become more upright in response to the warmer days and lack of snow cover. In the heat of a dry summer, the leaves also will lie down closer to the earth. The plants resume growth in the fall as other plants are starting to go dormant, developing a mound of deep grey-green leaves. The leaves are evergreen in areas without severe cold or there is protective snow cover, though they often turn purple, orange, or reddish. The flowers of G. triflorum appear from mid-spring to early summer. The flowering stalks stand well above the leaves on red-purple-maroon stems 10–45 cm (3.9–18 in) in height. The flowering stem is almost bare with a few very small leaves called bractlets on the main stem and where the arching flower stalks (pedicels) attach to the main stem. Each flower hangs upside down by itself from a separate pedicle. There are usually three flowers on each flower stalk, but sometimes one, five, or even seven per stalk. The sepals are strongly closed and pink to maroon in color, covered in fine downy hairs, with five narrow pointed bracts radiating outward toward the base of the flower. The flowers contain five 7–13 mm long elliptical petals mostly to entirely hidden under the sepals. They are most often a light yellow to cream, but sometimes have a blush of pink or purple; they have purple veins.
When pollination is completed, the flower heads turn upright and the sepals begin to open. The petals may be visible at this stage. The many styles grow longer, eventually becoming 15–70 mm in length. The styles are densely covered in fine hairs making them resemble downy bird feathers or wisps of mauve smoke. The seed heads start pale pink and fade to tan or grey as the seeds mature in mid-summer. The seeds do not appear to need cold stratification, as germination did not change significantly when tested.
Taxonomy
Geum triflorum was named and described by German–American botanist Frederick Traugott Pursh in his book Flora americae septentrionalis using an 1811 collection by naturalist John Bradbury. He placed the species within Carl Linnaeus's Geum, a genus with a name derived from Greek for "taste", with the species name of Geum triflorum for the three flowers usually present on each flower stalk. The species previously had been collected in Idaho on 12 June 1806 by American explorer Meriwether Lewis but was not described by him. That specimen was incorrectly described as a new species named Geum ciliatum by Pursh. German botanist Kurt Sprengel placed it in Sieversia as S. triflora in his update of Systema Vegetabilium published in 1825. This classification was eventually rejected as was the 1906 attempt by American botanist Edward Lee Greene to create a new genus that would reclassify G. triflorum as Erythrocoma triflora and separate a dozen regional varieties as separate species.
Varieties and forms G. triflorum has three varieties that are accepted by many, but not all, authorities, as of January 2023.
Geum triflorum var. campanulatum (Greene) C.L.Hitchc. Geum triflorum var. canescens (Greene) Kartesz & Gandhi Geum triflorum var. ciliatum (Pursh) Fassett
Geum triflorum var. campanulatum Geum triflorum var. campanulatum was described as a separate species, Erythrocoma campanulata, by Greene and as Geum campanulatum by English-born botanist George Neville Jones, but American botanist Charles Leo Hitchcock argued for its classification as a variety of G. triflorum in 1961, writing, "There has been much diversity of opinion regarding both the generic status of, and significance of the variation in, this complex. In general the several taxa that have been recognized at the specific level are largely sympatric and completely transitional and there seems to be no good reason to recognize more than 3 races for our area...". This has become the accepted view as researched by botanist Richard Pankhurst. It differs in having leaflets that are rounder (obovate-cuneiform instead of cuneiform), shorter leaves overall, and flowers that are more open or bell-shaped (campanulate). It was described from a type specimen found in the Olympic Mountains. It is recorded by the USDA Natural Resources Conservation Service PLANTS database (PLANTS) as growing in Washington state and Oregon. This variety is accepted by World Flora Online (WFO) and PLANTS, but not Plants of the World Online (POWO) or Flora of North America (FNA).
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