Sow Thistle
Sonchus oleraceus
Also known as: Common Sow Thistle, Milk Thistle, Soft Thistle, Hare's Thistle
'Sonchus' is the ancient Greek name for thistle. 'Oleraceus' means 'of the kitchen garden' or 'vegetable-like' – marking this plant's long history as an edible pot herb. 'Sow thistle' refers to the plant's traditional use as food for nursing sows (pigs), who were said to be particularly fond of it; 'hare's thistle' reflects its value as food for hares and rabbits. Sow thistle is one of Australia's most abundant urban and coastal weeds – a soft-leaved annual or biennial of the daisy family (Asteraceae) found in gardens, parks, roadsides, coastal dunes, and disturbed ground across the entire continent. It is a true thistle relative but, crucially, much softer than true thistles – the leaf margins are prickly, not dangerously spiny, and the plant is entirely edible. It has been eaten by humans, pigs, rabbits, and birds across the world for thousands of years. Young plants are especially tender and mild.
When to Forage
Year-round in temperate climates; most abundant and tender in autumn through spring.
Cautions
Very safe. The milky latex in the stems is harmless and can be simply rinsed away. As with all members of the daisy family, those with severe ragweed or composite allergies should be cautious. Avoid sites with heavy herbicide use. Older leaves can be quite bitter – blanching resolves this.
Nutrition
Rich in vitamins A and C; calcium, iron, potassium, and magnesium. Contains beneficial flavonoids and phenolic compounds with antioxidant activity. The milky sap contains compounds (sesquiterpene lactones) with mild sedative and anti-inflammatory properties – responsible for the slightly bitter flavour. Nutritionally comparable to spinach.
How to Identify
- Upright or sprawling annual, 30–100 cm tall. All parts exude a milky-white latex when cut or broken – a reliable confirming feature.
- Basal and lower leaves are deeply lobed (pinnatifid), with a large terminal lobe and smaller lateral lobes; margins have soft, slightly prickly teeth that are flexible and not painfully sharp.
- Upper stem leaves clasp the stem with distinctive rounded, ear-like lobes (auricles) at their base – a key identification feature for this species.
- Flowers are small, pale yellow composite heads (like a miniature dandelion), borne in loose clusters at the top of branching stems.
- Achenes (seeds) have a feathery pappus – tiny dandelion-like parachutes dispersing on the wind.
Lookalikes
Very similar but leaves are darker, glossier, and the spine-teeth on the margins are harder and more prickly. The clasping stem leaves have more pronounced rounded auricles. Also edible but less palatable; tougher texture.
Much more aggressively spiny – leaf margins have hard, sharp, painfully pointed spines unlike the flexible teeth of sow thistle. True thistles are also edible (stems peeled, roots, receptacle) but require much more preparation.
Similar basal rosette and yellow flowers, but leaves are rougher and more hairy, without the soft prickly-toothed lobing of sow thistle, and without the milky latex.
How to Forage
Harvest the entire young plant before it flowers, or pick tender young leaves from the growing tips. Before flowering, the whole plant can be uprooted and used. The youngest, brightest-green leaves are the mildest; older leaves and large plants become progressively more bitter. Eat young leaves raw in salads; blanch or sauté older leaves to tame the bitterness. Rinse well to remove the milky sap. Flowers are edible as garnishes.
Recipe — Sow Thistle and White Bean Soup
Ingredients: 3 large handfuls sow thistle leaves (tender, blanched and roughly chopped); 1 can white beans (cannellini or butter beans), drained; 1 onion, diced; 4 cloves garlic, sliced; 1 litre vegetable stock; 2 tbsp olive oil; juice of 1 lemon; salt, pepper, chilli flakes; good bread to serve. Method: Blanch sow thistle leaves in boiling salted water for 2 minutes; drain, refresh, and chop roughly. Sauté onion in olive oil until soft and golden, about 8 minutes. Add garlic; cook 2 minutes. Add stock and white beans; simmer 10 minutes. Stir in chopped sow thistle; cook 3 minutes. Season generously with salt, pepper, and chilli. Squeeze in lemon juice. Serve with plenty of good bread and a drizzle of olive oil.
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