Ohio Noxious Weed Identification – Week 7 Musk Thistle

Musk Thistle

Family: Composite, Asteraceae.

Habitat: Pastures, meadows, wasteland, and roadside ditches. Found sporadically throughout Ohio.

Life cycle: Biennial, forming a rosette the first year and producing flowers and seed in the second.

First Year Growth Habit: A basal rosette. Leaves are waxy and pale green with few hairs.

Second Year Growth Habit: Large, coarse, branched plant that can grow up to 9 feet.

Leaves: 3-6 inches long, alternate, spiny, deeply lobed, long and narrow.

Stem: Stems covered with dense, short hairs and spines.

FlowerJune – October. Purple thistle-like flower heads, 1-2” wide borne singly on stems; spiny-tipped bracts surrounding flower head. Often the flower heads droop or nod, hence the other common name of Nodding thistle.

Fruit: Seeds borne in white or tan feathery structures, similar to dandelion, spread by wind.

Similar plants: In the first year of growth, musk thistle may resemble bull thistle (Cirsium vulgare). However, the leaves of bull thistle are covered with hairs. Musk thistle is also referred to as nodding thistle.

The problem is….This prickly weed reduces the quality of grazing land. It has spread quickly throughout much of the Midwest, but is not yet common in Ohio. Avoid handling without gloves.









Whole Plant







Currently there are 21 weeds on the Ohio Prohibited Noxious Weed List:

  • Shattercane (Sorghum bicolor) – February 8
  • Russian thistle (Salsola Kali var. tenuifolia) – February 22
  • Johnsongrass (Sorghum halepense L. (Pers.))
  • Wild parsnip (Pastinaca sativa)
  • Wild carrot (Queen Anne’s lace) (Daucus carota L.)
  • Oxeye daisy (Chrysanthermum leucanthemum var. pinnatifidum)
  • Wild mustard (Brassica kaber var. pinnatifida)
  • Grapevines: when growing in groups of one hundred or more and not pruned, sprayed,cultivated, or otherwise maintained for two consecutive years. – February 15
  • Canada thistle (Cirsium arvense L. (Scop.))
  • Poison hemlock (Conium maculatum)
  • Cressleaf groundsel (Senecio glabellus)
  • Musk thistle (Carduus nutans) – March 26
  • Purple loosestrife (Lythrum salicaria)
  • Mile-A-Minute Weed (Polygonum perfoliatum) – March 7
  • Giant Hogweed (Heracleum mantegazzianum) – March 14
  • Apple of Peru (Nicandra physalodes) – February 28
  • Marestail (Conyza canadensis)
  • Kochia (Bassia scoparia)
  • Palmer amaranth (Amaranthus palmeri)
  • Kudzu (Pueraria montana var. lobata)
  • Japanese knotweed (Polygonum cuspidatum)

Each week, for the next 21 weeks, I will post information and pictures on how to identify these invasive and harmful plants.

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