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Cirsium undulatum - (Nutt.)Spreng.

Common Name Wavy-Leaved Thistle, Tracy's thistle
Family Asteraceae or Compositae
USDA hardiness 4-9
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.
Habitats Dry open soils[43]. Prairies, pastures and roadsides in Texas[274].
Range Western N. America - British Columbia to Texas.
Edibility Rating    (3 of 5)
Other Uses    (2 of 5)
Weed Potential Yes
Medicinal Rating    (1 of 5)
Care (info)
Fully Hardy Well drained soil Moist Soil Full sun
Cirsium undulatum Wavy-Leaved Thistle, Tracy


Cirsium undulatum Wavy-Leaved Thistle, Tracy
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 3: 550.

 

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Summary

Wavy thistle is one of the most widespread and recognizable native thistles of western North America, occurring from plains to foothills and into lower mountain zones. It is a classic biennial thistle that produces a substantial taproot in its first year and a flowering stalk in its second. From a foraging perspective, it is a reliable and worthwhile species, offering edible roots and excellent peeled stems when harvested at the correct stage. Its abundance, wide distribution, and consistency make it one of the more practical thistles for wild food use.


Physical Characteristics

 icon of manicon of flower
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.

UK Hardiness Map US Hardiness Map

Synonyms

Plant 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].

References   More on Edible Uses

Medicinal Uses

Plants For A Future can not take any responsibility for any adverse effects from the use of plants. Always seek advice from a professional before using a plant medicinally.
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].

References   More on Medicinal Uses

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Other Uses

Oil

The seed of all species of thistles yields a good oil by expression[4]. No details of potential yields etc are given[K]. The flowers provide abundant nectar for bees, butterflies, and other pollinators. Seeds are eaten by birds, and the plant contributes to soil stabilization in open habitats.

Special Uses

References   More on Other Uses

Cultivation details

Wavy thistle is one of the most dependable and practical native thistles for foragers, offering high-quality roots and excellent peeled stems across a wide geographic range. Growing Conditions: Wavy thistle thrives in full sun and tolerates a wide range of soil types, including compacted, sandy, or clay soils. It is especially common in disturbed ground and open grasslands. Habitat & Range: Native to western and central North America, wavy thistle occurs throughout the Great Plains, Southwest, Rocky Mountains, and adjacent regions. It is common along roadsides, rangelands, open prairies, and foothill slopes. Size & Landscape Performance: Plants typically reach 60–100 cm tall, though smaller or larger individuals occur depending on soil fertility and moisture. It grows as scattered individuals rather than dense monocultures. Cultivation (Horticulture): Wavy thistle is not cultivated intentionally. Its spines and aggressive seed production limit garden value, though it could theoretically be managed as a wild root crop. Pests & Problems: Few serious pests affect wavy thistle. Grazing pressure is low due to spines, allowing plants to mature and seed freely. Pollination: Pollinated primarily by bees and butterflies attracted to the large, nectar-rich flower heads. Identification & Habit: Wavy thistle begins life as a low basal rosette of deeply lobed, spiny leaves with characteristically wavy margins, a feature that gives the plant its common name. In the second year, it produces a stout, upright flowering stem that is typically unbranched or sparsely branched. Leaves along the stem are alternately arranged, spiny, and often clasp the stem at the base. The flower heads are large, showy, and usually lavender to pinkish-purple, borne singly or in small clusters near the stem tips. The plant has a robust, muscular appearance compared to more delicate meadow thistles.

References   Carbon Farming Information and Carbon Sequestration Information

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Plant Propagation

Seed - sow early spring or autumn in situ. Germination usually takes place within 2 - 8 weeks at 20°c[164].

Other Names

If available other names are mentioned here

Gray thistle, Wavyleaf thistle, Wavy-Leaved Thistle, Tracy's thistle, Wavy Thistle (Cirsium undulatum)

Native Range

NORTHERN AMERICA: Canada (Alberta, British Columbia, Manitoba, Saskatchewan), United States (Indiana, Michigan, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, South Dakota, Wisconsin, Colorado, Idaho, Montana, Washington, Wyoming, New Mexico, Texas, Arizona, California, Utah), Mexico (Chihuahua, Coahuila de Zaragoza, Durango, Sonora)

Weed Potential

Right plant wrong place. We are currently updating this section. Please note that a plant may be invasive in one area but may not in your area so it's worth checking.

Moderate. This plant can be weedy or invasive. It is a weed in California and Northwestern Mexico. Know as a Noxious Weed in: Arkansas, California and Iowa, USA. While native, wavy thistle can become locally abundant in disturbed areas, though it does not spread aggressively by rhizomes like field thistle.

Conservation Status

IUCN Red List of Threatened Plants Status : This taxon has not yet been assessed.

Related Plants
Latin NameCommon NameHabitHeightHardinessGrowthSoilShadeMoistureEdibleMedicinalOther
Cirsium acaulonStemless ThistlePerennial0.3 4-8  LMHNM012
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Cirsium arvenseCreeping Thistle, Canada thistlePerennial0.9 3-8 FLMHNM222
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Cirsium brevistylumIndian Thistle, Clustered thistlePerennial1.8 0-0  LMHSNM302
Cirsium buergeri Perennial1.8 -  LMHNM102
Cirsium chinense Perennial0.8 -  LMHNM102
Cirsium coreanum Perennial0.0 -  LMHSNM102
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Cirsium drummondiiDwarf thistleBiennial0.4 4-8 FLMNDM301
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Cirsium eriophorumWooly ThistleBiennial1.5 5-9  LMHNM202
Cirsium foliosumElk thistlePerennial0.6 5-9  LMHNMWe302
Cirsium hookerianumWhite ThistlePerennial1.5 -  LMHNM202
Cirsium japonicumNo-Azami, Japanese thistleBiennial/Perennial0.9 5-9  LMHNM222
Cirsium kamtschaticumKamchatka thistlePerennial1.8 0-0  LMHNM102
Cirsium lepskyle Perennial0.0 -  LMHNM102
Cirsium lineare Perennial1.0 -  LMHNM102
Cirsium maackii Perennial1.0 -  LMHNM102
Cirsium maritimum Perennial0.4 -  LMHNM102
Cirsium neomexicanumNew Mexico thistlePerennial1.0 4-8 FLMNM301
Cirsium nipponicum Perennial1.5 -  LMHNM112
Cirsium occidentaleCobwebby Thistle, Snowy thistle, Compact cobwebby thistlePerennial1.0 8-11  LMHNDM202
Cirsium ochrocentrumYellow Spined ThistlePerennial1.0 4-8  LMHNDM322
Cirsium oleraceumCabbage ThistlePerennial1.2 -  LMHSNMWe202
Cirsium oligophyllum Perennial1.0 -  LMHNM202
Cirsium pallidumPale ThistleBiennial1.0 4-8  LMHNM212
Cirsium palustreMarsh ThistleBiennial1.5 4-8  LMHSNMWe202
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Growth: S = slow M = medium F = fast. Soil: L = light (sandy) M = medium H = heavy (clay). pH: A = acid N = neutral B = basic (alkaline). Shade: F = full shade S = semi-shade N = no shade. Moisture: D = dry M = Moist We = wet Wa = water.

 

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Author

(Nutt.)Spreng.

Botanical References

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Subject : Cirsium undulatum  
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