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Pest Information

Anderson's Thistle

Anderson's Thistle

  • Latin Name: Cirsium Andersonii
  • Common Name: Anderson's Thistle
  • Other Names: Rose thistle

Pest Details

Anderson's Thistle
Anderson's Thistle

Origin:

A native thistle in the Pacific states, occurring in California, Nevada, and Oregon.

Biology:

A biennial or a perennial plant, reproducing from seeds. Foliage dies back in the winter, with re-growth from the roots beginning in early spring. It is found in open pine forests and in dry meadows, but also can be a noxious weed in grain fields, roadsides, or other disturbed sites.

Identification:

The mature plant can grow to over 2 feet tall with an erect, woody stem. The stem is slender and a reddish color, with no branches to a very few branches. The leaves begin as a thick rosette at the soil, with other leaves growing well separated and alternate along the developing stems. Lower leaves may be 14 inches long and have dense hairs on their lower surface. Leaves are elongate, lance-shaped, and with wavy to toothed margins. The flower develops at the end of the stem as a tubular flower that never opens fully. It is about 2 inches long with the base enclosed in the spiny bracts. Petals are reddish to reddish purple.

Characteristicts Important to Control:

Where only a few plants exist they can be physically removed or killed with a contact herbicide. Prevention relies on a pre-emergent herbicide placed prior to seed germination.

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