Douglas County Currently Listed Noxious Weeds

Puncturevine / Russian Knapweed / Diffuse Knapweed / Canada Thistle / Perennial Pepperweed / Hoary Cress / Yellow Starthistle

Tribulus Terrestris - Puncturevine (Goathead)

Annual that will form a dense mat.  Grows in dry, hot conditions in waste areas and roadsides. Will mature, flowers will shed and form dry, hard burs.  Average adult size, 2' to 5' in diameter.

Acroptilon Repens - Russian Knapweed

Perennial that form dense colonies which prevent other plants from competing.  Will grow from seed or root fragment and is very difficult to control once established.  Easily identified by black roots.  Average adult size, 8" to 4'.

Centaurea Diffusa - Diffuse Knapweed

This is a short lived perennial that prefers drier sites in range lands and roadsides.  Numerous white flowers, possibly purple.  It's highly competitive, but easier to control than other Knapweeds.  Changes from bushy appearance during first year to scraggly, multi-branched plant during second year, to bush at maturity.  Average adult size, 6" to 2.5'.

Cirsuim Arvense - Canada Thistle

This is a colony forming perennial with an extensive root system.  Will grow from seed or root fragment and is very difficult to control once established.  Prefers moist sites.  Many small purple flowers about 3/4".  Average adult size, 3" to 4".

Lepidium Latifolium - Perennial Pepperweed (Tall White Top)

Perennial plants which need abundant moisture to begin development.  Once development occurs, then site can become dry and plant still flourishes.  This plant can develop from root fragments or seeds and is very difficult to control once established.  Average adult size, 2' to 5'.

Cardaria Draba - Hoary Cress (Short White Top)

Perennial plants that grow on disturbed sites.  This plant can develop from root frangipanis or seeds and is very difficult to control once established.  Blooms in late spring.  Average adult size, 2" to 18".

Yellow Star Thistle

Annual sun-loving plant with yellow flowers and sharp thorns.  This plant will cause "chewing disease" in horses if forced to eat.  The mature plant may flower at 2" and can grow to 3.5'.

Nevada Listed Noxious Weeds, Isolated Locations

Dalmation Toadflax / Tamarisk / Rush Skeleton Weed / Scotch Thistle / Spotted Knapweed

Linaria Dalmatica - Dalmation Toadflax

Perennial, aggressive roadside and rangeland weed that reproduces by seed and root.  Leaves are waxy and grey-green in color.  They will clasp the stem and yellow flower heads have a distinctive spur.  Plants may reach 3' tall.

 Tamarisk

Coming Soon

Chondrilla Juncea - Rush Skeleton Weed

Perennial that is a highly invasive, rangeland weed, inhabiting well drained, light soils.  Cut surfaces produce milky sap.  Extensive deep tap root.  May reach 4' tall with yellow 3/4" diameter flowers.

Onopordum Acanthium - Scotch Thistle

Biennial plants grow in disturbed areas from seed.  Flowers are 2", reddish/purple in color, with a single flower at the end of each branch.  Lower leaves may be prickly and huge, up to 8" wide and 16" long.  When mature, plant may reach 6' tall.

 Spotted Knapweed

Coming soon.