Sonchus arvensis (Perennial Sow-Thistle) - photos and description

 

 

 


Upper stem leaf in above photo


Lower stem leaf in above photo

General: Tall, weedy species with extensive horizontal root system. Stem is hollow. Plant exudes a milky sap. Plant glabrous.

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 5.5 cm in diameter.

Leaves: Leaves are alternate, clasping, lanceolate to obovate, entire above to deeply lobed below. Leaves reduced upwards. Lower stem leaf highlighted in photo above was 13 cm long by 6.5 cm wide. Lobes of leaves are spiny.

Height: Height listed in Budd's Flora to 150 cm tall, we measured plants to 143 cm tall.

Habitat: Roadsides, wet soils, waste areas.

Abundance: Common.

Origin: Introduced.

When and where photographed: Photos taken August 2nd, grassy roadside, about 70 km east of our home in Regina, SK.