Musk Thistle

(Carduus nutans) 

COMMON NAMES, Nodding plumeless thistle

Photos

Rosette

rosette

Mature plants

carduus6_5_41

Pre-bloom flower

flower

Flower

flower head

Flower / seed head

seeds

Seed Head

seed head

BACKGROUND

Native to southern Europe and western Asia, musk thistle thrives in pastures and rangelands, in waste areas, stream banks, and road sides.

DESCRIPTION

Musk thistle is a biennial or winter annual. Plants 4 to 6 feet tall are common. Deeply lobed spiny leaves are distinguished by a dark green blade with a prominent light green midrib. Stems are spiny and appear winged. Flowers may be violet, purple, or rose colored. Flowers are typically “nodding” or bent over. A tuft of white hairs is attached to each seed, which develops together at maturity and displaces the flowerhead. Bloom is in June and July.

CONTROL

Several biocontrol agents are available and offer good control. Herbicides can offer good to excellent control when applied between rosette and pre-bud stages. Mechanical means can be used for control by chopping the plant off at the ground.