Sowthistle, perennial (Sonchus arvensis)

Sowthistle, perennial description

Perennial sowthistle is a tall creeping perennial with flowers that resemble dandelions. Plants can be 2-4 ft high, and they produce a milky sap.

Propagation

Perennial sowthistle reproduces by seed or root propagation.

Similar species

The easiest way of differentiating perennial sow-thistle from annual sow-thistle is to examine the roots systems. The flowers of perennial sow-thistle are larger than those of annual sow-thistle.

Distribution

Perennial sowthistle is common in cropland and ditches throughout the country.

Identifying Sowthistle, perennial

Seedling

Cotyledons round to oval, with slight indentations at the tips. Cotyledons wither, but usually remain, after true leaves develop. First few true leaves alternate, elliptic to oval with the base narrower than the tips, with toothed edges and soft prickles.

Mature plant

Stems erect, branching near the top, 2 to 5 feet high at maturity. Stems smooth below to slightly hairy near the top, hollow, with a milky sap.



Leaves alternate, elliptic in outline. Lower ones up to 10 inches long, lobed and irregularly toothed (similar to dandelion), with soft prickles, leaves narrow into winged stalks. Upper leaves smaller, with fewer lobes and teeth, short stalked to stalkless and clasping the stem. Leaves have a milky sap.

Root structure description

Deep, horizontal, creeping roots.

Flowers

Bright yellow, up to 1-1/2 inches across, in groups of heads at ends of branches. Flowers June to late September. Seeds small, rectangular, brown with lengthwise ridges and a tuft of white hairs on top end.