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Musk Thistle

Carduus nutans

Other Common Names

Nodding Plumeless Thistle

Plant Category

Biennial

Invasive Description

Native to Eurasia, Musk Thistle was possibly accidentally introduced in 1852 through ballast water. It is an aggressive, spiny plant with showy red-purple flower heads that droop or nod. It resembles several native thistles. Seedlings may emerge at any time from spring to late summer and develop a rosette. Plants overwinter in the rosette stage, sending up a multi-branched flowering stem in mid-spring of their second year. Mature plants range in height from 1.5 to 6 feet tall.

Ecological Threat

Musk Thistle forms dense stands that can replace much of the native vegetation in pastures and disturbed areas. Its spines make it unattractive to wildlife and livestock, giving Musk Thistle a competitive advantage. Difficult to control since one flower head may produce 1,200 seeds and single plant up to 120,000 seeds, which are spread by animals and wind. Seeds may remain viable in soil for over ten years.

You may not want or need to replace this invasive plant, but if you do, options are listed below.

How to Eradicate

For information on how to eradicate this invasive, view our statement on herbicide use and preferred alternatives for invasive plants.

Native Alternatives

You can replace this invasive plant with native alternatives. Here are some plants that make superior replacements.

Match your location on the Texas map to the color squares on the replacement plants below to find suitable replacements for your ecoregion.

Click for more details about the ecoregions
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About the Region

New Braunfels, the location of our Fall 2024 Symposium, straddles both the Edwards Plateau Ecoregion and the Blackland Prairie ecoregion. Interstate 35 divides the city of New Braunfels; its path through the city closely parallels the boundary of these two ecoregions, with the Edwards Plateau on the west side and the Blackland Prairies region to the east. The Edwards Plateau area is also called the Hill Country; however, this general term covers a much larger area extending farther north. Spring-fed creeks are found throughout the region; deep limestone canyons, rivers, and lakes (reservoirs) are common. Ashe juniper is perhaps the most common woody species found throughout the region. Additional woody species include various species of oak, with live oak (Quercus fusiformis) being the most common. Sycamores (Platanus occidentalis) and bald cypress (Taxodium distichum) border waterways. This area is well known for its spring wildflower displays, though they may be viewed in spring, late summer, and fall, as well. According to Texas Parks and Wildlife, average annual rainfall in the Edwards Plateau ranges from 15 to 34 inches.

The Blackland Prairie extends from the Red River south to San Antonio, bordered on the west by the Edwards Plateau and the Cross Timbers, and on the east by the Post Oak Savannah. Annual rainfall averages 30 to 40 inches, with higher averages to the east. This region is dominated by prairie species. The most common grass species include little bluestem (Schizachyrium scoparium) and Indian grass (Sorghastrum nutans) in the uplands and switchgrass (Panicum virgatum) in the riparian areas and drainages. Common herbaceous flowering plants include salvias, penstemons, and silphiums. This area has suffered greatly from overgrazing and agricultural use. Few intact areas remain, though many of the plants can be found along county roadsides throughout the region.

Our four host chapters (New Braunfels, Lindheimer, Guadalupe, and the Hill Country chapters) are located in one or both of the ecoregions above. However, the eastern portion of Guadalupe County also falls within the Post Oak Savanna ecoregion. Annual rainfall averages 35 to 45 inches, with higher averages to the east. A wide variety of hardwood trees are found, including several species of oaks, elms, and in the Bastrop area, loblolly pine (Pinus taeda). Grasses and forbs dominate in the open savannas, with most common grass being little bluestem. Ranching, agriculture, and fire suppression have allowed woody species to encroach on the once-open savannas.

Source: Wildflowers of Texas by Michael Eason