Sonchus arvensis L.
Perennial sowthistle, field milk thistle, field sowthistle, corn sow thistle, dindle, gutweed, swine thistle, tree sow thistle
Perennial sowthistle is a Eurasian native, now widespread throughout North America. It is considered invasive in some habitats. Sowthistles are actually related to wild lettuce (Lactuca), not thistles.
Plants: Up to 5′ (1.5 m) high. Stems are dull green, unbranched and hairless below the flowers, exuding a milky sap when cut. Stem bases are hard and may be woody. While many other sowthistles are annuals, these perennials are more likely to occur in groups, spreading underground. See this comparison of three similar species.
Leaves: Alternate, 2–16 ⨉ ¾–6″ (6–40 ⨉ 2–15 cm), hairless, with soft spiny toothed edges. They are variably pinnate. Leaf bases are ear-shaped, with straight or curved rounded auricles. Basal leaves are large, and densely spaced. Upper leaves become smaller, less lobed and more spread out.
Flowers: Loosely branched clusters of flowers are bright yellow, and 1–1¾″ (3–5 cm) in size. Plants produce lots of flowers—up to 350—but only a few at a time. Bracts and flower stalks are covered with golden yellow glandular hairs, or in some subspecies, glands without hairs. Flowers open 2-3 hours after sunrise and close at noon. They appear from June to October.
Fruits: Dark reddish brown seeds 1/16–⅛″ (2.5–3.5 mm) long, with tufts of white hairs to carry them.
Habitats: Pastures, meadows, roadsides, shorelines, and disturbed habitats.
Edibility: Young leaves are edible in salad. They can be boiled like spinach, but the water should be changed once, to avoid excessive nitrate levels.
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Similar species. |
Online References:
8/2/2008 · Flying Mountain, Bar Harbor, Maine · ≈ 2½ × 2″ (6.1 × 5.3 cm) 
ID is uncertain 
8/20/2025 · Peaks Island, Maine · ≈ 2 × 1½′ (71 × 51 cm) 
7/27/2015 · Two Lights, Cape Elizabeth, Maine · ≈ 2 × 1¾″ (5.6 × 4.6 cm) 
7/27/2015 · Two Lights, Cape Elizabeth, Maine · ≈ 2½ × 2″ (7.3 × 5.3 cm) 
9/21/2021 · Pott’s Point Preserve, Harpswell, Maine 
9/18/2016 · Deer Isle Beach Vegetation Reclamation Project 
9/18/2016 · Deer Isle Beach Vegetation Reclamation Project 
7/27/2015 · Two Lights, Cape Elizabeth, Maine · ≈ 4 × 2½″ (9.9 × 6.6 cm) 
9/21/2021 · Pott’s Point Preserve, Harpswell, Maine 
9/21/2021 · Pott’s Point Preserve, Harpswell, Maine 
8/20/2025 · Peaks Island, Maine · ≈ 6 × 7″ (15 × 18 cm) 
8/20/2025 · Peaks Island, Maine · ≈ 13 × 11″ (32 × 27 cm) 
9/21/2021 · Pott’s Point Preserve, Harpswell, Maine 
9/21/2021 · Pott’s Point Preserve, Harpswell, Maine 
| Kingdom | Plantae | Plants, but not fungi, lichens, or algae (from Stearn's Botanical Latin) |
| Subkingdom | Tracheobionta | Vascular plants—plants with a “circulatory system” for delivering water and nutrients |
| Division | Magnoliophyta | Flowering plants, also known as angiosperms |
| Class | Magnoliopsida | Dicotyledons—plants with two initial seed leaves |
| Subclass | Asteridae | A large class that encompasses asters |
| Order | Asterales | Flowering plants with a central disk flower and surrounding petals, like daisies |
| Family | Asteraceae | The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers |
| Genus | Sonchus | Greek for “sowthistle” |
| Species | arvensis | Of the fields |
Sonchus arvensis description by Thomas H. Kent, not updated.
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