Desert Knapweed (Volutaria tubuliflora)

Category A Weed

Asters family (Asteraceae)

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Stem

  • To 5 ft. tall; forms basil rosette, then rapid growth forms flower stems; lower parts of flowering stems are winged

Leaves

  •  Fuzzy leaves with deep, rounded lobes; leaves decrease in size higher on the plant

Flower

  • White to pink to purple petals; 0.5 in. tall and 0.5 in. wide with fuzzy hairs at their base; flowers often appear to have no petals; bracts at the base of the flower have light brown, pointed spines; seeds are tiny, barrel-shaped and have a crown of fine hairs that aid in wind dispersal

Other

  • Grows best on disturbed ground and seasonally flooded sites. No known occurrences in Nevada
  • Winter annual; each plant can produce several thousand seeds; seed remains viable in soil for several years
  • Can outcompete native vegetation by rapid growth which shades out other plants

Control

  • Mechanical removal by pulling, digging or hoeing is effective; if plant is flowering, bag up plant and dispose of properly.
  • Apply aminocyclopyrachlor+chlorsulfuron, aminopyralid or clopyralid preemergence or post emergence in the seedling to rosette stage; apply 2,4-D or dicamba post emergence during rosette to early bolting stage

Images

Mature plant
Roots
Leaves
Flower