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Cirsium undulatum

Species category

Weed

Common name

wavyleaf 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.
 and curved

Size

  • Length: 7 mm
  • Width: 2.5 mm
  • Thickness: 2 mm

Color

Brown with a yellow apicalApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
 rim

Texture

Rough and shiny with faint longitudinal ribs

Other structures

Strong stylarStylar:
The end of the fruit or seed that contains the style or the apical end.
 knob

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.
 obovate with one side straight and the other curved. Many faint longitudinal ridges over a shiny but rough texture. Color yellow-brown with apical rim yellow. Prominent stylarStylar:
The end of the fruit or seed that contains the style or the apical end.
 knob which protrudes well above the apicalApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
 rim. Scar basalBasal:
The base of the fruit or seed opposite the apical end.
. One of the larger Cirsiums.

Noxious weed seed categories

State Noxious Weed: California 

AOSA examination list

Not included

Nomenclature

Family

Asteraceae

Valid name

Cirsium undulatum (Nutt.) Spreng.

Cirsium undulatum. Yellow-brown achenes with a yellow apical rim.
Cirsium undulatum. Yellow-brown achenes with a yellow apical rim.
On the Top: Carduus nutans . From Left to Right: 1. Cirsium undulatum 2. Cirsium vulgare 3. Cirsium arvense . Achenes with many faint longitudinal ridges over a shiny but rough texture. 
On the Top: Carduus nutans. From Left to Right: 1. Cirsium undulatum 2. Cirsium vulgare 3. Cirsium arvense. Achenes with many faint longitudinal ridges over a shiny but rough texture.