Fremont Noxious Weeds

This list is based on the New 2007 Weed Rules and is then categorized to fit the needs of Fremont County weed control efforts.


Invasive weeds (Noxious Weeds) that are not currently found in Fremont County, but are in neighboring counties or states. These weeds are to be eradicated immediately and any seed source is to be bagged and buried at the landfill.

  • Brazilin elodea (Egeria densa p.)
  • Common curpina (Cirsium arvense)(L.)Scop.
  • Giant hogweed (Heracleaum mantegazzianum)
  • Orange hawkweed (Hieracium aurantiacum)
  • Hydrilla (Hydrilla verticillata)
  • Scotch boom (Cytisus scoparius)
  • Squarrose knapweed (Centaurea vitgata)Lam.ssp.squarrosa Gugl.
  • Tall hawkweed (Heiracium piloselloides)
  • Syrian bean caper (Zyggophyllum fabago) L.
  • Tansy ragwort (Senecio jacobea)
  • Toothed spurge (Eughorbia dentate)
  • Yellow hawkweed (Heiracium pretence)
  • Yellow starthistle (Centaurea solstitialis)L.
  • Eurasian water milfoil (Myriophyllum aquticum)
  • Giant knotweed (Polygonum sachalinesnse)
  • Water hyacinth (Eihhornia crassipes M.)
  • Mediterrainean sage (salvia aethiopsis)
  • Parrotfeather milfoil (Myriphylum aquiticum)
  • Yellow devil hawkweed (Hiercium glomeratum)
  • Bohemian knotweed (poygonum bohemicum)
  • Common crupina (Crupina vulgaris)
  • Vipers bugloss (Echium vulgare)
  • Small bugloss (Anchusa arvenis)
  • Milium (Milium vernale)
  • Policeman's helmet (Impatiens glandulifera)
  • Purple loosestrife (Lythrum salicaria)
  • Buffalo bur (Solanum rostranum)
  • Jointed goat grass (Anglos cylindrical)
  • Perennial pepperweed (Lepidium lattfolium) L.
  • White top (Cardaria draba)(L.) Desv.

Minimal Presence

Invasive (Noxious) Weeds that have a minimal presence in Fremont County. These have such a minimal presence in Fremont County that it is believed they can be eradicated within a year or two and then closely monitored after that.

  • Plumless thistle (Carduus acanthoides)
  • Japanese knotweed (Plolygonum cuspidatum)
  • St. Johns wart (Hypericum perforatum)
  • Rush skeleton weed (Chondrilla juncea)
  • Dyers woad (Isatistinctoria) L.
  • Black hembane (Hyoscyarrius niger)L.
  • Diffuse knapweed (Centaurea diffusa) Lam.
  • Scotch thistle (Onopordum acanthium)L.
  • Oxeye daisy (Chrysanthemum leucannthemum
  • Saltcedar (Tamarix)
  • Puncturevine (Tribulus terrestris) L.
  • Musk thistle (Carduus nutans) L.
  • Russian knapweed (Centaurea repens)L.
  • Poison hemlock (Conium maculatum)
  • Silver leafy nightshade (Solanum elaeagnifolium) Cav.


Weeds that pose the greatest threat to property. These weeds are given the greatest amount of attention during the day-to-day activities of Fremont County Weed Department

  • Dalmation toadflax (Linara dalmatica) L.
  • Hounds tongue (Cynoglossum offinale) L.
  • Leafy spurge (Euphorbia esula)
  • Mayweed chamomile (Anthemis cotula)
  • Spotted knapweed (Centaurea maculosa) Lam.
  • Yellow toadflax (Linaria vulgaris)

High Presence

Noxious weeds that have a high presence in Fremont County but cannot be economically controlled at the present time. These weeds will be monitored and controlled/ managed as to keep there numbers to a minimum.

  • Canada thistle (Cirsium arvense)(L.) Scop.
  • Field bindweed (Convolvulus arvensis) L.
  • Johnsongrass (Sorghum halepense)
  • White bryony (Bryonia alba)