Practical ecological knowledge for the temperate reader.

Sonchus Sp. - Sow Thistle

Family: Aster

(Above)Sonchus asper

(Above)Sonchus asper

(Above)Sonchus asper

"Annual to perennial herb [shrub]; sap milky. Stem: erect, smooth, distally branched. Leaf: basal and cauline, alternate, ± entire to toothed and coarsely pinnate-lobed; cauline generally sessile, clasping. Inflorescence: heads liguliflorous, in cyme-like clusters; involucre swollen at base; phyllaries generally in 3 series, outer many, short-triangular, inner series linear, tapered; receptacle ± flat, epaleate. Flower: many; ligule yellow, readily withering. Fruit: generally ± flat, beakless; pappus of many fine, white bristles."
"± 55 species: Eurasia, Africa. (Ancient Greek name for a kind of thistle) [Hyatt 2006 FNANM 19:273–276]"
"Unabridged references: [Boulos 1972–74 Bot Not 125:287–319, 126:155–196; 127:7–37, 402–451]" [Jepson]

"Sow-thistles have milky latex; true thistles do not." [PCBC] "All three sow-thistle species were introduced to North America from Europe and are well-known weeds. the perennial sow-thistle being considered one of the worst weeds of all. Each species occurs throughout Canada. Perennial sow-thistle is most common in Quebec. Ontario, and the Prairie Provinces, while the other two are prevalent in Qlwbee, Ontario, and British Columbia." [EGWC]

Local Species;

  1. Sonchus arvensis - perennial sow-thistle [E-flora][PCBC]
  2. Sonchus asper - prickly sow-thistle [E-flora][PCBC]
  3. Sonchus oleraceus - common sow-thistle [E-flora][PCBC]

Sonchus arvensis L. - Perennial sow-thistle

"Perennial sow-thistle is a common introduced weed species in southern British Columbia that originates in Europe. It is found along roadsides and in other disturbed sites. It can be identified by the yellow composite (daisy-like) flower heads with strap-shaped flowers, lack of basal leaves, and prickly-margined stem leaves. Plants exude milky juice when broken." [????]

Sonchus asper (L.) Hill - prickly sow-thistle

Sonchus oleraceus L. - Common sow-thistle


S. oleraceus; "Latex allergenic (VAD), possibly causing tenesmus (AHL). May cause liver problems in animals (ROE). As of July 2007, the FDA Poisonous Plant Database listed four titles alluding to toxicity of this species." [Duke MPLA] "Sonchus has laxative properties, and so should be eaten in moderation." [NHF]

" species is poisonous, so any with tender foliage can be eaten. Be aware that when growing in chemically fertilized soils, they may accumulate toxic amounts of nitrates." [UWP]

Species Mentioned

S. arvensis, S. asper, and S. oleraceus [EGWC]

Edible Uses

Other Uses

Medicinal Uses


S. oleraceus; "Abortifacient (f; UPW); Analgesic (f; MPG); Antibilious (f; JFM); Antiinflammatory (f; FAH; MPG); Antioxidant (1; X14630594; X15800389); Antiradicular (1; X14630594); Antisarcomic (1; MPG; WOI); Antiseptic (f; MPG); Antispasmodic (f; EGG; JFM; MPG); Antitumor (1; MPG; WOI); Antiulcer (f; MPG); Aperitive (f; JFM); Carminative (f; EGG; JFM; MPG); Cathartic (f; KAB; WBB); Cholagogue (f; MPG); CNS-Sedative (f; MPG); Collyrium (f; WBB); Depurative (f; JFM; MPG); Digestive (f; FAH); Diuretic (f; GHA); Emmenagogue (f; DEM; FAH); Emollient (f; AHL; ROE); Febrifuge (f; DEP; KAB); Fungicide (f; EGG); Hepatotonic (f; FAH; MPG); Hydragogue (f; NAD); Lactagogue (f; JFM; NAD; ROE; WOI); Laxative (f; GHA; JFM); Litholytic (f; FAH); Narcotic (f; WOI); Neurotonic (f; JFM); Orexigenic (f; JFM); Purgative (f; ROE); Refrigerant (f; JFM); Sedative (f; KAB); Stomachic (f; EGG; JFM; MPG); Tonic (f; GHA; KAB); Vermifuge (f; FAH; WBB)." [Duke MPLA]

Nutritional Info

Common Sow-Thistle - S. Oleraceus [218] [PFAF]

Part: Leaves (Dry Weight) Per 100 g fresh weight

Calories 265
Riboflavin (mg) 5
Vitamin A (mg) 35
Water (g) 0.00%
Niacin (mg) 5
Calcium (mg) 1500
Protein (g) 28
Vitamin C (mg) 60

Phosphorus (mg) 500
Fat (g) 4.5
Ash (g) 22
Iron (mg) 45.6
Carbohydrate (g) 45
Fiber (g) 5.9
Thiamine (mg) 1.5

S. oleraceus; "Nutritionally, sow thistle is higher in omega-3 fatty acids, zinc, and manganese than any of our domesticated greens. In fact, it has the highest source of manganese of any of the foods in our two charts. It has amounts of copper and iron, and average amounts of beta-carotene, vitamin C, calcium, and fiber." [Kallas] A weed in cultivated lands, introduced from Europe. Now found over most of the cultivated regions of the world. Used in Great Britain and Germany as a potherb. Said to be "exceedingly wholesome." [EWP,1962]


Harvesting: Sonchus oleraceus "Saw thistle is an annual. The leaves and roots are best gathered in the spring before the plant has flowered." [Nyerges]

S. asper; "Succeeds in most soils in a sunny position. This plant has been cultivated for its edible leaves by the Maoris in New Zealand[153]." [PFAF]

S. arvensis; "This species has been cultivated for its edible leaves by the Maoris of New Zealand, in Indonesia there are improved varieties selected for their edible leaves[153, 183]. A good companion for onions, tomatoes, corn as well as the cucumber and squash family[20]." [PFAF]


Page last modified on Sunday, January 2, 2022 9:13 PM