Photo Gallery (U.S. National Park Service)

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Tamarix ramosissima

Salt Cedar / Tamarisk

2048 x 1536
2.7 MB

Artemisia absinthium

Absinth wormwood

1704 x 2272
2.0 MB

Cirsium arvense - Canada thistle is an aggressive, creeping plant that infests hundreds of acres of park land and over 500,000 acres in the state of North Dakota. Generally, the plant infests disturbed ground, reducing forage for wildlife.

Canada thistle

1536 x 2048
2.2 MB

If your park visit includes a trip to the North Unit in July and August, you will become intimately aware of the presence of Canada thistle. The campground is highly infested with this thorny, prickly plant.

Canada thistle infestation

1944 x 2592
2.4 MB

Hyoscyamus niger

Black henbane

1536 x 2048
2.2 MB

Centarurea repens, Russian knapweed. The similar spotted knapweed, Centaurea maculosa, is also found in the park.

Russian knapweed

2112 x 2816
2.3 MB

Euphorbia esula - The leafy spurge infestation is estimated near 4,000 acres (about 10%) in the South Unit of the park. Heaviest concentrations are found along stream beds, drainages and wooded draws.

Leafy spurge

2448 x 3264
4.5 MB

In North Dakota, leafy spurge infests nearly 1 million acres. It costs North Dakota farmers and ranchers $27 million in direct impacts every year. Total economic impact to the state is estimated at $86 million.

Chemical control of Leafy spur...

2448 x 3264
2.7 MB

Intensive management is necessary and is Theodore Roosevelt National Park's highest priority in resource management. Control efforts focus on leafy spurge ( Euphorbia esula ), spotted knapweed ( Centaurea maculosa ), Russian knapweed ( Centarurea repens ), Canada thistle ( Cirsium arvense ), black henbane (Hyoscyamus niger), absinth wormwood (Artemisia absinthium) and salt cedar (Tamarix ramosissima).

IPMT Crew Spraying

1704 x 2272
1.8 MB

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