Blue Flowers


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  • A many-branched perennial
  • Grows up to 6 feet tall from a deep taproot
  • Lower leaves are deeply toothed
  • Upper leaves are sparse and small, giving the plant a stemmy look
  • Many sporadic flowers are white to bluish-purple and up to 1 inch in diameter
  • Contains a milky juice
  • Remove prior to seed set by pulling, hoeing or mowing
  • Herbicides may be needed

Yellow Flowers

Yellow Starthistle

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  • An annual to short-lived weed that spreads by seed only
  • Grows one to three feet tall
  • Bright yellow flower heads are about 1 inch in diameter
  • Inch-long spines form at ends of bracts under flowerheads
  • Stems are winged, but not spiny
  • Grows along roadsides and in waste areas and grasslands
  • Pull, dig or mow at first sign of yellow flowers
  • Chemical controls are available

Curlycup Gumweed

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    • Biennial or short-lived perennial
    • Grows 1 to 3 feet tall with fibrous root systems
    • Leaves are about one inch long, rounded at the tip, toothed on the edges and grow alternately on the stem
    • Yellow flowers are about one inch in diameter and sticky or gummy underneath
    • Commonly seen growing along roadsides
    • Difficult to remove by hand or weed wacker
    • Herbicides are available


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  • Annual
  • Forms flat, spreading mat with stems up to 5 feet long
  • Leaves are small and include 4 to 8 pairs of leaflets
  • Flowers are tiny, yellow, and have 5 petals
  • Produces many spiny fruits that break apart into tack-like “goatheads” that can puncture tires and feet
  • Plant continues to flower and produce seed until frost
  • Remove prior to seed set by pulling, hoeing or digging; easiest when plant is small
  • Herbicides are available.

White Flowers

Russian Thistle

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    • Bushy annual that grows 6 inches to 3 feet tall
    • Reproduces by seed
    • Seedlings resemble tiny pine trees
    • Stems are often striped red or purple; mature plants may have a reddish appearance
    • Leaves grow alternately on the stem, are string-like at the base, and grow shorter and spine-tipped at the top of the plant
    • Spiny flowers grow inconspicuously where the upper leaves join the stem
    • Dead plants will break off and roll with the wind, scattering seeds
    • Herbicides are available and plants should be sprayed during the early stages of life



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    • Annual
    • Grows 1 to 6 feet tall
    • Stems are highly branched
    • Leaves grow alternately, are lance-shaped, and about 2 inches long
    • Leaves are hairy underneath with a smooth upper surface
    • Flowers grow among the upper leaves inconspicuously, and form short spikes at the top of the plant
    • Remove prior to seed set by pulling, hoeing or mowing
    • Easily controlled mechanically in the seedling stage
    • Herbicides are available

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