Sonchus arvensis aka Field Sowthistle

Sonchus arvensis is also called perennial sowthistle. It belongs to Asteraceae, the daisy family. Its native range spans temperate parts of Europe and Asia. Britain and Ireland form part of that range. This herbaceous plant lives for years but loses its leaves in winter. It grows on farms, roadsides, waste ground, and ditch edges. It also grows by saltwater and brackish shores, where fresh and salt water mix.

Plants reach about 3.3–4.9 feet [1–1.5 metres] tall. Their spread reaches 1.6–3.3 feet [0.5–1 metre]. They reach full size in one or two years. Creeping stems, called stolons, help them spread beyond the first clump. The upright stems have grooves and stiff hairs. Upper leaves clasp the stems. They have rounded lobes at their bases. Small prickles line the leaf edges.

Gold-yellow flowerheads bloom from midsummer into autumn. Each head measures about 0.13–0.16 feet [0.04–0.05 metres] across. Loose groups of heads grow at the stem tops. Bracts surround each head and bear sticky, yellow-tinted glands. The plant spreads with ease from seed as well. This helps it persist on ground that people work.

Grow perennial sowthistle in full sun, in soil that drains well. It suits moist soil and tolerates chalk, clay, loam, and sand. The RHS says acid, neutral, and alkaline soils all suit it. Yet Plants For A Future says wild plants avoid acid ground. Its H7 rating shows it withstands cold below −20°C in European conditions. The RHS suggests wildflower meadows and wildlife gardens as planting sites. Yet the plant can cause trouble in lawns, beds, and borders. It needs no pruning, but you need to watch its spread. Pests rarely cause trouble. Powdery mildew and leaf spot may still occur.

Plants For A Future lists young leaves, stems, and roots as edible. Eat young leaves raw in salads, or cook them. They taste slightly bitter and supply vitamin C. You may remove the edge prickles, but need not. Cooked stems and young roots also serve as food. Roasted roots can take the place of coffee. The source lists no known hazards. This does not prove the plant is wholly safe. It records folk uses of leaves in poultices and calming teas. People have also used root teas for chest complaints. These records do not prove that such treatments work. The source also notes possible use to kill insects. It gives no evidence here that this use works.