Wavy-Leaved Thistle, Tracy's thistle

Cirsium undulatum

Physical Characteristics

Cirsium undulatum is an evergreen Perennial growing to 0.6 m (2ft) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 5. 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 dry or moist soil.

Distribution

Western N. America - British Columbia to Texas.

Habitats

Cultivated Beds;

Edible Uses

Edible Parts: Oil Root Stem Edible Uses: Oil A high-value wild vegetable, best utilized for its taproots and young stems when harvested at the correct stage. Edible Uses & Rating The taproot and young stems are the primary edible parts. Roots are edible before flowering, and stems are excellent when harvested young and peeled. Leaves are technically edible but impractical because of their heavy spines and bitterness. Overall, wavy thistle ranks as a high-value edible thistle, especially for its roots and stems [2-3]. Taste, Processing & Kitchen Notes: Roots are starchy, mild, and only faintly bitter, with a flavor comparable to burdock and a potato-like undertone. Cooking improves both texture and flavor, and simmering produces a nourishing broth. Peeled stems are crisp, juicy, and mildly sweet, often compared favorably to celery. Fibrous strands are present but manageable. Cooking softens the stems while preserving sweetness, though chewing remains necessary because of residual fiber [2-3]. Seasonality (Phenology): Roots are best harvested from late autumn through early spring, before the flowering stalk emerges. Stems are harvested in spring when elongating but still tender. Flowering typically occurs from late spring through summer. Safety & Cautions (Food Use): Sharp spines require gloves during harvest. Harvest only from abundant populations and avoid protected lands. Ensure roots are collected before flowering for best quality. Harvest & Processing Workflow: For roots, identify first-year rosettes or second-year plants before flowering, dig deeply to remove the taproot, scrub clean, and cook thoroughly. For stems, cut young flowering shoots, peel away the spiny outer layers, and consume raw or cooked [2-3]. Cultivar/Selection Notes: No cultivars exist. Look-Alikes & Confusion Risks: Wavy thistle resembles several native Cirsium species. Confusion is generally safe, as most native thistles have similar edible properties. Avoid confusing with knapweeds or star-thistles (Centaurea), which lack edible roots. Traditional / Indigenous Use Summary: Roots and stems were used by multiple Indigenous groups across the Plains and Southwest as seasonal vegetables, particularly during spring and early summer. Root - raw or cooked[46, 61, 105, 161, 257]. One of the more palatable thistles, it is used as a vegetable or can be added to soups and stews[212, 257]. It can be dried and stored for winter use[257]. 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 - peeled and eaten raw or cooked[161, 212, 257]. One of the more palatable thistles[212].

Medicinal Uses

Ophthalmic VD A decoction of the root has been used in the treatment of gonorrhoea[257]. A cold infusion of the root has been used as a wash for eye diseases[257].

Known Hazards

Sharp spines require gloves during harvest. Harvest only from abundant populations and avoid protected lands. Ensure roots are collected before flowering for best quality.