Weed of the Week
June 19th 2006
Musk Thistle, Carduus nutans (L.)
Characteristics
Family: Asteraceae (Sunflower)
Origin: Southern Europe and Western Asia, introduced in the early 1900's
Description:
- Biennial, or winter annual
- Forms a rosette with a large tap root in first season of growth
- Bolts, flowers, and sets seed in the second year of growth
- Reproduces by seed
Stems:
- Erect, branched, spiny
- Grows up to 6 feet tall
- Can appear to be bush-like in appearance
Flowers:
- 1-2 1/2" deep rose, or purple colored flowers
- Flower head is disk shaped and often nodding in appearance, surrounded by numerous spiny bracts
- Bloom occurs May-August
- Seeds are oblong and straw-colored
Leaves:
- Rosette leaves can grow to 2 ft in diameter and dark green, deeply lobed and spiny along margins
- Once bolted smaller, spiny, leaves clasp the stem, 6" leaves are deeply lobed
Location:
Musk Thistle is often found in pasture and rangeland, along roadways and ditch banks. It is easily differentiated when compared to Canada Thistle by the size and shape of the seed heads. Musk Thistle has much larger seed heads, which angle down or sideways off the stem and the spines are much more visible.
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