Field Thistle thumbnail
Plants of the Eloise Butler Wildflower Garden

Common
Name

Scientific
Name

Plant
Family

Garden
Location

Prime
Season

Field Thistle

Cirsium discolor (Muhl. ex Willd.) Spreng.

Aster (Asteraceae)
Upland
Late Summer
Other names and notes

Most people don't grow thistles as ornamentals but you have to admit the flower is nice and is very attractive to bees and butterflies. Stems: Plants can reach up to 7' in height with erect lateral branching. Stems are light green and have white hair giving the plant an overall silvery appearance. The plant is usually biennial, forming a basal rosette the first year and sending up the tall stem the second year. Leaves: Leaves are alternate, pinnately divided, spiny, and large - up to 9" long. The upper side is dark green and the under appears whitish due to many fine hair. The Inflorescence consists of single flower heads on erect stems branching from the top of the plant. The flower heads are up to 1 1/2" wide and are densely filled with small pinkish-purple 5 lobed disk flowers. The base of the flower head has a large series of phyllaries that look like fish scales, are lighter green in color with a white central stripe (a vein). The outside of the head is very prickly as each phyllary has a single slender spine. At the very base of the head are a set of floral bracts that look like ascending miniature leaves. Flowers do not have a fragrance. Seed: The flowers mature to a dry achene that has attached some white fuzzy hair for wind dispersion.

Habitat: Field Thistle prefers full sun with medium moisture in loamy soils - a typical open field environment. It grows from a tap root and does not spread vegetatively but re-seeds by wind dispersion of the seeds. The flowers provide an attraction for bees and butterflies and the seeds are preferred by the American Goldfinch. See Eloise Butler's notes below. Comparisons: Here is a comparison sheet of the 7 thistles found in Minnesota.
Field Thistle Field Thistle Field Thistle plant
Above: Field thistle usually has single flower heads on stems branching from the top of the plant. Heads are about 1-1/2" wide with pinkish-purplish tubular disk flowers. The small leaves ascending from under the head (photo left) are actually bracts and not true leaves. The plant can be quite large and tall (photo right).
Field Thistle Bud
Field Thistle flower stem
Above: On this flower bud you can see the fish-scale-like floral phyllaries with a vertical white stripe and each with a yellow spine projecting. Below: Each seed has fine white pappus attached for wind dispersion.
Field Thistle
 
 

Notes: Eloise Butler had catalogued four thistles in her plant index as present in the Garden area. Field Thistle was one of them. It was also listed on Martha Crone's 1951 inventory of plants in the Garden at that time. It is native to Minnesota in a band of counties running from the SE corner to the NW, plus Lake County. In North America it is found in the eastern half of the continent, Florida and the Canadian maritime provinces excepted. In a few states, such as Iowa and Arkansas, it is classified as a noxious weed.

Eloise Butler wrote about Thistles: "The Scotch made no mistake in selecting the thistle for their national flower. Bristling with needle-like prickles, a type of stern independence, it does not admit of close intimacy. But we are captivated by its reddish purple blooms, fragrant as roses and brimmed with sweetness. Economical and thrifty, the thistle can wrest a living from the scantiest means; but “ower canny” as it is, it sends out myriads of plumy seeds, by which it will establish itself in richer soil whenever the opportunity offers. The voracious caterpillar crawls by it to plants with unarmed herbage; the thistle is browsed only be underfed donkeys. It is often decked with winged visitants of black and gold, the thistle birds or goldfinches, surrounded by drifting clouds of silvery plumes, as they lightly swing on the matured flower heads and eagerly break them apart to obtain their favorite food. The buds, the beautiful flower clusters, the feathery balls of fruit, and the deeply lobed leaves with ruffled margins of the thistle, all readily lend themselves to designs for ornament."

"The Field Thistle, Cirsium discolor, is particularly lovely by reason of its pale pink, or sometimes white flowers, and long, drooping leaves. The bull thistle [Cirsium vulgare] has larger heads and still more formidable prickles; while the tall swamp thistle is less stout and spiny. [C. muticum Michx.]. These species are not undesirable for a garden, if one has space enough to keep them at arm’s length. But no good word can be said for the Canada Thistle, an emigrant from Europe that multiplies apace, although allowed no rights of citizenship. It seems useless to legislate against it; for it has a running root stock that spreads while we sleep, and the seeds fly over the country to sow discomfort everywhere. It is a pest because it is so difficult to keep within bounds. If you wish to know just how Theophilus Thistlewaite thrust three thousand thistles through the thick of his thumb (too low an estimate by far!), clear by hand a plot of land that has been overrun by Canada Thistles." Published August 27, 1911, Minneapolis Sunday Tribune

  
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References: Plant characteristics are generally from sources 15, 16, 30, 31, 33, W2 & W3. Distribution principally from W2 and also 31, 34 and W1. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.  
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