Slender Sowthistle

Mediterranean region.

Annual or perennial.

Sonchus tenerrimus was known historically on ballast from Alabama, Pennsylvania (Philadelphia), New Jersey, New York, and, possibly, Quebec.

Annual, biennials, or perennials, 10–80 cm. Stem bases soft to hard, herbaceous, often hollow. Leaves: blades of mid cauline oblong, 3–20 × 2–6 cm, bases auriculate, auricles ovate to lanceolate or linear, ± straight, obtuse to acute, margins usually pinnately lobed, lobes ± rhombic to lanceolate (constricted at bases) or ± linear, terminals ± equaling laterals, entire or dentate. Peduncles usually setose- to stipitate-glandular, often tomentose as well, sometimes glabrous. Involucres 10–12+ mm. Phyllaries usually setose- to stipitate-glandular, sometimes tomentose as well. Corollas: ligules longer than tubes. Cypselae reddish brown, oblanceoloid, 2.5–3.5 mm, ribs 1–3 on each face, faces transversely rugulose or tuberculate across and between ribs; pappi 5–8 mm. 2n = 14.

Sonchus tenerrimus is a species of flowering plant in the family Asteraceae known by the common name slender sowthistle. It is native to the Mediterranean region of southern Europe, northern Africa, and the Middle East. It has been found as well in several other locations around the world, historically in association with ship ballast in coastal regions. It has become naturalized in a few places, such as California in the United States and Baja California in Mexico.

Sonchus tenerrimus is an annual or perennial herb producing a slender, branching stem up to about 80 centimeters (32 inches) tall. The leaves are deeply divided into many variously shaped lobes which may have toothed edges or smaller lobes. The inflorescence bears flower heads lined with glandular, hairy to woolly phyllaries. They are filled with numerous yellow ray florets but no disc florets. The fruit is an achene up to a centimeter long including its pappus.