Canada thistle (Cirsium arvense) and Bull thistles (Cirsium vulgare)
Today's featured weed is the thistle, Cirsium spp., including Canada thistle, AKA creeping thistle, small-flowered thistle, perennial thistle and green thistle and the bull thistle (Cirsium vulgare), both of which are common in my yard.
Identification of Thistles
Canada thistle (Cirsium arvense) presents itself as narrow, leggy plants that sprout along a central stalk. The spines, while pokey, are not nearly as sharp as bull thistle spines.
Seedlings can pop up anywhere, as only a single seed or a remnant of root is necessary to propagate a whole new plant. The Canada thistle commonly grows in clumps of plants, because it will spread by runners. The blossoms of these plants are much loved by butterflies and other pollinators. This summer we've had a lot of European skippers visiting our plants.
To remove thistles, it's best to catch them when they are young and small. When the soil is loose, such as after a rain, it's fairly easy to pull them and get a long section of root, even barehanded. Simply grab at the very base of the plant, where it is less spiny, or even just below the soil line.
Their roots are very brittle and break off easily (which allows them to regrow), but with frequent cultivation and mulching they are readily brought under control. (Barbara Pleasant recommends the same thing in The Gardener's Weed Book – other than the bare-handed pulling.)
Bull thistles (Cirsium vulgare) are exactly that – bullish. I once joked with my husband that the best thing about our Canada thistles is that they weren't bull thistles (when we first moved here, the place was overrun with thistles). They start out as low rosettes close to the ground, and then shoot up a large flower stalk the second year (they are biennials). Strangely enough, I had a hard time tracking down one to get a clear picture, as our population has been greatly reduced and most that are left are in the tall grass.
I usually use a fork and heavy gloves to pull out these, unless I can catch them small and get under the rosette.
Thistles as Food and Medicine
Both thistles are classified as noxious weeds in many areas, but they are both edible. In The Forager's Harvest, Samuel Thayer goes into some detail about how thistles were one of the first wild foods he foraged, and how he harvests the center spine of the leaves by peeling off the surrounding spiny leaf material, leaving a stalk like a celery stick. He describes them and being tender, juicy and delicious. In the interest of science, I went out this morning in the 90+F temps and found a bull thistle leaf, peeled it and ate it on the spot. It tasted like grass. I was underwhelmed. Still, if I'm in a pinch, at least I know they are safe to eat. The flowering stalks can also be cleaned and eaten, but are best early in the season, before they are in full bloom (I'm a little late). The roots, too, are edible, and Thayer says “better than burdock”. I ate some raw burdock last fall, and they weren't too bad, so I may give those a try this fall.
Canada thistle can be used medicinally. Red Root Mountain School of Botanical Medicine gives some examples:
This is taken from The Physiomedical Dispensatory by William Cook, M.D., 1869 Medical Herbalism. I do hope you all enjoy. I certainly have.
Description: Natural Order, Compositae. It would be superfluous to give any detailed description of that pest to all good farmers-the Canada thistle. Suffice it to say that it contains qualities which really are deserving of medical investigation; and it will be a pleasant thing to know that the unfriendly herb may yet be put to some good uses.
Properties and Uses: The roots are slightly demulcent, with stimulating and mildly astringent properties. An ounce simmered in a pint of milk is a family remedy for low forms of diarrhea and dysentery, after the acute symptoms have subsided. Two fluid ounces of such a decoction may be taken every two or three hours.
An infusion is said to expedite labor very effectually, when the nervous system has become fatigued-also anticipating after-pains and flooding. I knew one gentleman to use a syrup of this root in long-standing coughs, where the expectoration was free and the lungs feeble; and he also used a wine tincture in mild leucorrhea and prolapsus. The leaves made into a decoction and used somewhat freely, are said to increase the flow of milk, and gently to overcome hepatic obstructions; and the juice makes a rather soothing wash (or ointment) for irritable sores, tender eyes, and piles.
Like most of my other weeds, I've largely made peace with my thistles, too. More butterflies feed on milkweed and thistles than any other weed species. Painted Lady butterflies prefer thistles as food plants for their larva. The painted lady is also known as the thistle butterfly, and its scientific name – Vanessa cardui – translates as “butterfly of thistle.”