Xeranthemum annuum

Species category

Weed

Common name

immortelle

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

Oblanceolate

Size

  • Length 3.8–5 mm 
  • Width 1–1.5 mm 
  • Thickness 0.7–0.9 mm 

Color

Yellow with black mottling; 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.
is lighter at apexApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
and darker at the base

Texture

Silky appressedAppressed:
Pressed close or lying flat against something.
hairs

Other structures

Triangular pappusPappus:
Modified calyx in Asteraceae, composed of hairs, bristles, awns, or scales. The pappus-like structure attached to milkweed seeds is termed a coma. 
scales are about half the 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.
length.

Identification notes

A small attachment ring is on the basalBasal:
The base of the fruit or seed opposite the apical end.
end. 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 can be considered a long triangle.

Noxious weed seed categories

Not listed

AOSA examination list

Not included

Nomenclature

Family

Asteraceae

Valid name

Xeranthemum annuum L.

Synonyms

Xeranthemum squarrosum Boiss

 Xeranthemum annuum.  Achenes with triangular pappus scales that are around half the length of the achene.
Xeranthemum annuum. Achenes with triangular pappus scales that are around half the length of the achene.