Creeping Thistle, Canada thistle

Cirsium arvense

Physical Characteristics

Cirsium arvense is a PERENNIAL growing to 0.9 m (3ft) by 1 m (3ft 3in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 4 and is not frost tender. It is in flower from July to September, and the seeds ripen from August to October. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, flies, Lepidoptera (Moths & Butterflies), beetles. The plant is self-fertile. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers moist soil.

Distribution

Europe, including Britain, from Scandanavia south and east to N. Africa and Asia.

Habitats

Meadow; Cultivated Beds;

Edible Uses

Edible Parts: Leaves Oil Root Stem Edible Uses: Curdling agent Oil Root of first year plants - raw or cooked[183]. Nutritious but rather bland, they are best used in a mixture with other vegetables[9]. The root is likely to be rich in inulin, a starch that cannot be digested by humans. This starch thus passes straight through the digestive system and, in some people, ferments to produce flatulence[K]. Stems - they are peeled and cooked like asparagus or rhubarb[9, 12, 177, 183]. Leaves - raw or cooked[177, 183]. A fairly bland flavour, but the prickles need to be removed before the leaves can be eaten - not only is this rather fiddly but very little edible leaf remains[K]. The leaves are also used to coagulate plant milks etc[46, 61, 183]. Foraging notes. Edible but inferior to biennial thistles, best used for young shoots and stems rather than roots. Edible Uses & Rating: Young shoots and peeled stems are the most practical edible parts of Canada thistle. Roots are technically edible but are usually thin, fibrous, and low in starch compared to biennial thistles, making them a secondary resource at best. Leaves are edible only after extensive trimming and cooking and are generally not worth the effort. Overall, Canada thistle ranks as a moderate- to low-value wild food, valuable primarily due to its abundance rather than superior quality [2-3]. Taste, Processing & Kitchen Notes: Peeled young stems are mild, slightly sweet, and comparable to celery, though usually more fibrous. Cooking softens the texture but does not fully eliminate stringiness. Roots lack the rich starchiness of biennial thistles and tend to be woody or hollow, with a mild but unimpressive flavor. Leaves are bitter and spiny and do not improve much with cooking. Shoots harvested very early in the season are the best-tasting part of the plant [2-3]. Seasonality (Phenology): Young shoots and stems are best harvested in early spring as new growth emerges. Roots may be harvested year-round but are best in late autumn or early spring when carbohydrate reserves are highest. Flowering occurs from late spring through summer. Safety & Cautions (Food Use): Spines pose a physical hazard. Roots may contain bitter resins that can cause digestive discomfort in sensitive individuals if eaten in quantity. Harvest & Processing Workflow: Harvest young shoots in early spring. Peel thoroughly to remove spines and outer fibers. Cook or eat fresh. Roots should be cleaned carefully, sliced thinly, and boiled to improve texture and flavor [2-3]. Cultivar/Selection Notes: No cultivars exist. Considerable variation occurs among populations. Look-Alikes & Confusion Risks: Other Cirsium species are similar and generally edible in similar ways. Avoid confusing with Centaurea species, which lack edible roots and stems. Traditional / Indigenous Use Summary: Canada thistle was reportedly eaten by some Indigenous groups, though documentation is sparse compared to native biennial thistles. Its use appears opportunistic rather than staple-based [2-3].

Medicinal Uses

Antiphlogistic Astringent Diuretic Emetic Emmenagogue Hepatic Tonic The root is tonic, diuretic, astringent, antiphlogistic and hepatic[207]. It has been chewed as a remedy for toothache[4]. A decoction of the roots has been used to treat worms in children[257]. A paste of the roots, combined with an equal quantity of the root paste of Amaranthus spinosus, is used in the treatment of indigestion[272]. The plant contains a volatile alkaloid and a glycoside called cnicin, which has emetic and emmenagogue properties[240]. The leaves are antiphlogistic[207]. They cause inflammation and have irritating properties[207[.

Known Hazards

Spines pose a physical hazard. Roots may contain bitter resins that can cause digestive discomfort in sensitive individuals if eaten in quantity.