Musk Thistle

Many members of the sunflower family are generically called “thistles”, whether they are true thistles or not. I suppose when we hear the word thistle most of us think of flowers in shades of purple/rose. My previous posts have included white, red and even yellow “thistles”. It suddenly dawned on me that I have ignored the most common purplish thistles. Time to correct that!

The musk thistle (Carduus nutans) was introduced from Southern Europe and Western Asia and now can be found throughout all of Continental United States except Florida. Adaptable to a wide range of soil conditions, musk thistle is usually found on open, disturbed or heavily grazed land and other waste areas. Spread vigorously by airborne seeds (up to 120,000 per plant) that can survive over ten years in the soil, musk thistle often becomes a serious problem for farmers. Therefore this plant, in addition to having a beautiful flower, has been declared a noxious weed in over 22 states.  A biennial, musk thistle germinates in the summer and forms a leaf rosette that overwinters. In the spring the rosette bolts (develops a flowering stem) and produces straw-colored seeds that resemble dandelion seeds.

Although farmers despise musk thistle, the flowers provide nectar for bees and other insects while the seeds nourish birds and small mammals. Finches love thistle seeds! Native Americans thought thistles had protective powers because of their prickly spines. As a talisman, they would place thistle leaves and roots in their pockets or in their bath water (carefully, I presume!). And like most true thistles, the peeled stem can be eaten and tastes good, particularly if harvested when the plant is young. I can vouch for the taste of musk thistle stems.

Musk thistle has deep rose flower heads that are usually bent over, giving C. natans another common name – nodding thistle. The grey purple anthers of the disc flowers that form the musk thistle head contrast with united rose colored petals. The involucral bracks that surround the base of the flower head are purple-red, a distinctive field marking for identification. The dark green leaves are coarsely lobed and have a light white or yellowish midrib. At the end of each lobe is a prominent white or yellowish spine. Very fine threadlike fibers encircle the flower head around the bracts.

The scientific name for musk thistle is descriptive: Carduus means “thistle” in Latin while nutans means “nodding”, referring to the head. Very simple!

These musk thistles were photographed near the Tule River (Shasta County CA).

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