Carduus pycnocephalus

Species category

Weed

Common name

Italian plumeless thistle

Diagnostic characters

Planting unit

AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.

Shape

ObovateObovate:
Inverted egg shaped with apical end the broadest.

Size

  • Length: 5 mm
  • Width: 2 mm
  • Thickness: 1.5 mm

Color

Light brown with dark brown longitudinal lines

Texture

Faint, transverseTransverse:
Set crosswise, crossing or at right angles.
wavy lines

Other structures

Large stylarStylar:
The end of the fruit or seed that contains the style or the apical end.
lobe and brown collar

Identification notes

AchenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
of this species are of two types: those from disc flowers and those from ray flowers. The diagnostic characteristics are for disc achenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
. Ray achenesAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
are grayish brown with dark flecks, dull textured and faintly pebbled.

Noxious weed seed categories

State Noxious Weed: California, Delaware, Hawaii, Maryland, Tennessee, Oregon, West Virginia, Virginia 

AOSA examination list

Not included

Nomenclature

Family

Asteraceae

Valid name

Carduus pycnocephalus L.

 Carduus pycnocephalus.  From Left to Right: 1. Ray flower achene 2. Disc flower achene. Achenes with a large stylar lobe and a brown collar.
Carduus pycnocephalus. From Left to Right: 1. Ray flower achene 2. Disc flower achene. Achenes with a large stylar lobe and a brown collar.