Go to Midwest Weeds and Wildflowers Home Page

Plumeless Thistle

Carduus acanthoides L.

Asteraceae (Sunflower Family)

▲▼ first year rosettes just before bolting

▲▼flowering plants

▲▼ flower buds

▲▼ inflorescences

 

▲▼ flowers, showing  winged, spiny stems and narrow outspread bracts below head inflorescences

▲▼ flowers, showing  winged, spiny stems and narrow outspread bracts below head inflorescences

▲▼ flowers, showing  winged, spiny stems and narrow outspread bracts below head inflorescences

▲▼ inflorescences with pointed bracts

 ▲ comparison between plumeless thistle flower (left) and musk thistle flower (right)

Carduus acanthoides L., Plumeless Thistle: (Bayer Code:  CRUAC; US Code:  CAAC)

         Biennial thistle very similar to musk thistle, except first year leaves are more narrow and deeply lobed, with more marginal spines

         Second-year flowering stem is moderately branched, with smaller leaves

         Flowers are smaller than musk thistle, (0.5-1.5 inches diameter) with more lanceolate/linear flat bracts, rather than triangular bracts seen on musk thistle

         No ray flowers, and disk flowers are pink to purplish

         Flowering season is late spring to early summer (May-June), which differs from other invasive thistles (Canada thistle,  bull thistle) that tend to bloom in mid to late summer (July-September)

         Found in pastures, along roadsides; more common in northern Midwest

 

 

Go to Midwest Weeds and Wildflowers Home Page

 

Updated 23 January 2019