Italian Thistle

Italian Thistle

Carduus pycnocephalus L.

Asteraceae (Sunflower Family)

▲ ▼ mature, flowering plants

▲ ▼ leaves, including some basal leaves below

▲ ▼ winged stems

▲ ▼ inflorescences

▲ fruit/seed

Carduus pycnocephalus L., ItalianThistle: (Bayer Code: CRUPY; US Code: CAPY2)

An annual to biennial weed native to Europe found only sporadically in Midwest so far, but potential for greater spread exists
First year rosette leaves long, narrow, deeply divided and have toothed, spine-edged margins
Subsequent flowering stem is 1-4 feet tall, slender, slightly-branched with leaf bases extending far down stem, so stem appears to have spiny wings; leaves on flowering stem are smaller than basal leaves
Inflorescence may be single or in small clusters, smaller than many thistles (usually 0.5 to 1 inch diameter), surround by outspread, spine-tipped, narrow-triangular bracts
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)

(Updated January 23, 2019)