Sonchus asper (Prickly Sow-Thistle) - photos and description



Leaves have rounded auricles.

Lower stem leaf in above photo.

Basal leaf in above photo.

General: A weedy annual species with prickly leaves. Stem is hollow, and the stem's surface is angled. Plants mostly glabrous. When these plants are bruised they exude a milky sap.

Has been declared a noxious weed in Saskatchewan.

Flowers: Flower heads ligulate, bright yellow in colour, grow in a terminal panicle. Flower heads measured to 17 mm in diameter. Flowers close by late morning.

Leaves: Leaves are alternate, spatulate, upper leaves clasping with rounded auricles. Upper leaves very prickly. Leaves reduced upwards. Upper leaf highlighted in photo above was 14 cm long by 4 cm wide. Lower and basal leaves have long petioles. Basal leaf highlighted in photo above was 16.5 cm long by 3.5 cm wide.

Height: Height listed in Budd's Flora to 150 cm tall, we measured plants to only 30 cm tall.

Habitat: Gardens, roadsides, disturbed soil.

Abundance: Common.

Origin: Introduced.

When and where photographed: Photos taken August 8th, bare soil in shrub bed along walking path, in our home city of Regina, SK.