FutureStarr

AMarsh Thistle

AMarsh Thistle

Marsh Thistle

Marsh Thistle is fairly easy to recognize, even passing by at 60 mph. It's generally tall (to 7+ feet) with a single stem, unbranched except near the top, with long, nearly leafless ascending branches and the short-stalked flower heads densely clustered at branch tips. The lower leaves are somewhat similar in shape to the native Swamp Thistle (Cirsium muticum) and the phyllaries are much like (the also invasive) Canada Thistle (Cirsium arvense), but Marsh Thistle has spiny winged stems, which the other two species lack. The spiny stems are characteristics of several other non-native purple thistles, which have spine-tipped phyllaries plus flower heads with longer stalks that aren't as densely clustered at branch tips. In any case, the spiny stem indicates a non-native thistle and it's best to eradicate it, no matter what species it is.

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Marsh Thistle is fairly easy to recognize, even passing by at 60 mph. It's generally tall (to 7+ feet) with a single stem, unbranched except near the top, with long, nearly leafless ascending branches and the short-stalked flower heads densely clustered at branch tips. The lower leaves are somewhat similar in shape to the native Swamp Thistle (Cirsium muticum) and the phyllaries are much like (the also invasive) Canada Thistle (Cirsium arvense), but Marsh Thistle has spiny winged stems, which the other two species lack. The spiny stems are characteristics of several other non-native purple thistles, which have spine-tipped phyllaries plus flower heads with longer stalks that aren't as densely clustered at branch tips. In any case, the spiny stem indicates a non-native thistle and it's best to eradicate it, no matter what species it is.

Marsh thistle occurs as a nonnative species in Wisconsin, Michigan, New York, Massachusetts, and New Hampshire in the United States and north to Newfoundland, Nova Scotia, Quebec, Ontario, and British Columbia in Canada [37,56,69]. It is native to Europe [17] and was first reported in North America in the early 1900s [79]. In the Great Lakes area, marsh thistle populations are considered "vastly under reported", although marsh thistle was reported in 10 northeastern counties in Wisconsin as of 2007 and is considered well established in Michigan. Populations in Canadian provinces and northeastern US states are scattered [56]. Plants Database provides a distributional map of marsh thistle.Marsh thistle was reported in New England by 1902 and in the Great Lakes area by 1934 (review by [56]). In New Hampshire, marsh thistle was first reported from East Andover in 1902. Plants occurred over a nearly 20-acre (8 ha) area in a "moist forest tangle" that was more than a mile (1.6 km) from the nearest town or cultivated area. Method of introduction was unknown. Marsh thistle was reported in South Boston in 1908 and in Newfoundland in 1910 [37]. In 1944, marsh thistle was reported in several communities near Halifax, Nova Scotia [54]. In Michigan, marsh thistle was first collected from Marquette County in 1934 [79]. It was first recorded in Wisconsin in 1961 [56]. In British Columbia, marsh thistle was first reported in 1954 [41]. Marsh thistle was reported during a 1964 survey of a ponderosa pine (Pinus ponderosa) forest in northwestern Nebraska [40]. However, no other sources reported marsh thistle in Nebraska as of 2009, suggesting that this population was transient or incorrectly identified. (Source: www.fs.fed.us)

 

 

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