Pennington County Local-Declared Weeds

Scott Guffey, Supervisor
Craig Smith, Crew Leader
LouAnn Blain, Admin

Pennington County
Weed & Pest
3607 Cambell Street
Rapid City, SD 57701
Phone: (605)394-5320
Fax: (605)716-3793

Contact Weed & Pest

SOUTH DAKOTA FACTS:

Canada thistle, originally from Eurasia, threatens the native, mixed prairie grasses and agricultural lands of South Dakota.

In 2005, between 1000 and 2500 acres in Pennington County were infected with Dalmatian Toadflax.

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Common Tansy Found in the Central and Northern Black Hills, it grows mainly in along the Rapid Creek drainage in Pennington County. Common Tansy is a perennial. It reproduces by both seed and root. Flowers are bright yellow, button-shaped, up to 1/2 inch across, flat topped and cluster densely at the top of the plant. Leaves are alternate and deeply divided into leaflets. Stems are stout, erect, and unbracted except for the flowering portion at the top. It grows 1 to 4 feet tall.

Dalmatian Toadflax This weed is a new invader into Pennington County and western South Dakota. The main infestation in Pennington County is found south of Rapid City along Highway 16. Dalmatian toadflax is a perennial. It reproduces by roots and a single plant can produce up to one-half million seeds. Its flowers are bright yellow snapdragon like, with an orange throat and a long spur. Leaves alternate and are light green, waxy, heart-shaped and clap at the stem. Stems are woody and grow 1 to 3 feet tall. Dalmatian toadflax was originally introduced to the west coast of North America as ornamental plant in about 1874.

Houndstongue Houndstongue is found throughout Pennington County, with the heaviest infestations in the Black Hills. Houndstongue is a biennial, reproducing by seed only. The flowers are small and reddish-purple in color. Seeds are about the size of a pencil eraser, burr-like with short barbs. Leaves are alternate and rough, with a shape like a dog's tongue hence the name of the plant. Stems are erect, branching above and grow 1 to 4 feet tall.

Puncture Vine Puncture Vine is found mainly in the central and eastern part of Pennington County. It is an annual, reproducing by seed only. Flowers are small, yellow, five-petalled, and arising at the leaf attachment. Seeds are burr-like and when mature can penetrate tire. Leaves are opposite, hairy, and oblong. Stems have stiff hairs, lie along the ground forming a dense map and can grow up to 5 feet in length.

Spotted Knapweed This weed is also an invader of Pennington County and western South Dakota. It is found mainly in the Box Elder Creek drainage in Pennington County. Spotted knapweed is a biennial or short-lived perennial, reproducing by seed. A rosette of leaves is formed the first year, a flower stalk is formed the second year. Flowers are pinkish purple, found mostly on branched tips. Bracts have a comb-like fringe that is black tipped giving the appearance of spots. Leaves are light grayish-green long, narrow and deeply lobed. Stems are erect with slender branches and grow 1 to 3 feet tall.

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