Invasive Plants are non-native plants that have been shown to spread from gardens into wilderness areas, outcompeting and displacing the native plants that our native ecosystems require to remain healthy and ecologically balanced. Many native insect species are unable to survive (particularly during their larval stage) without eating the native plants they evolved alongside. Many native birds are unable to survive (particularly when first hatched) without eating insects, and insects are also an important food source for various other wildlife species, so not only does a loss of native plants leads to a loss of insects, but it leads to continued losses all the way up the food chain.

Different plants can be invasive in different geographic areas, so the California Invasive Plant Council (Cal-IPC) conducts extensive research to determine which plant species are invasive in California and rate their level of invasiveness. These are the Cal-IPC-rated invasive plant species that are known to grow in Yolo County.

One of the best places in Woodland to see invasive weed tree species is Pioneer Park. The City of Woodland has planted seven different invasive weed tree species there. In addition, 4th Street and Elm Street have six invasive weed tree species each among their street trees planted by the city.

Invasive Trees

Invasive Small Trees or Large Shrubs

Invasive Shrubs

Invasive Vines

Invasive Perennial Herbs

  • Capeweed (Arctotheca calendula)
  • Prostrate Capeweed (Arctotheca prostrata)
  • Thoroughwort (Ageratina adenophora)
  • Alligator Weed (Alternanthera philoxeroides)
  • Australian Saltbush (Atriplex semibaccata)
  • Iceplant (Carpobrotus edulis)
  • Purple Starthistle (Centaurea calcitrapa)
  • Diffuse Knapweed (Centaurea diffusa)
  • Skeleton Weed (Chondrilla juncea)
  • Canada Thistle (Cirsium arvense)
  • Bull Thistle (Cirsium vulgare)
  • Poison Hemlock (Conium maculatum)
  • Brass Buttons (Cotula coronopifolia)
  • Cardoon (Cynara cardunculus)
  • Wild Teasel (Dipsacus fullonum)
  • Brazilian Waterweed (Egeria densa)
  • Water Hyacinth (Eichhornia crassipes)
  • Eggleaf Spurge (Euphorbia oblongata)
  • Fennel (Foeniculum vulgare)
  • Little Robin (Geranium purpureum)
  • Jerusalem Artichoke (Helianthus tuberosus)
  • Bristly Ox-tongue (Helminthotheca echioides)
  • Mustard (Hirschfeldia incana)
  • Klamathweed (Hypericum perforatum)
  • Hairy Cat's Ear (Hypochaeris radicata)
  • Yellowflag Iris (Iris pseudacorus)
  • Hairy Whitetop (Lepidium appelianum)
  • Lens-podded Hoary Cress (Lepidium chalepense)
  • Whitetop (Lepidium draba)
  • Perennial Pepperweed (Lepidium latifolium)
  • European Sea Lavender (Limonium duriusculum)
  • Dalmatian Toadflax (Linaria dalmatica ssp. dalmatica)
  • Sweet Alyssum (Lobularia maritima)
  • Six-petal Water Primrose (Ludwigia hexapetala)
  • Marsh Purslane (Ludwigia peploides)
  • Hyssop Loosestrife (Lythrum hyssopifolia)
  • Purple Loosestrife (Lythrum salicaria)
  • White Horehound (Marrubium vulgare)
  • Pennyroyal (Mentha pulegium)
  • Parrot's Feather (Myriophyllum aquaticum)
  • Water Milfoil (Myriophyllum spicatum)
  • Scotch Cottonthistle (Onopordum acanthium)
  • Bermuda Buttercup (Oxalis pes-caprae)
  • Pokeweed (Phytolacca americana)
  • Ribwort (Plantago lanceolata)
  • Crispate-leaf Pondweed (Potamogeton crispus)
  • Jointed Charlock (Raphanus sativus)
  • Russian Knapweed (Rhaponticum repens)
  • Sheep Sorrel (Rumex acetosella)
  • Curly Dock (Rumex crispus)
  • Lily of the Valley Vine (Salpichroa origanifolia)
  • Milk Thistle (Silybum marianum)
  • Woolly Mullein (Verbascum thapsus)
  • Purpletop Vervain (Verbena bonariensis)
  • Periwinkle (Vinca major)
  • Calla-lily (Zantedeschia aethiopica)

Invasive Annual Herbs

  • Fivehorn Smotherweed (Bassia hyssopifolia)
  • Mediterranean Lineseed (Bellardia trixago)
  • Black Mustard (Brassica nigra)
  • Common Mustard (Brassica rapa)
  • Mustard (Brassica tournefortii)
  • Italian Thistle (Carduus pycnocephalus)
  • Slender-Flowered Thistle (Carduus tenuiflorus)
  • Woolly Distaff Thistle (Carthamus lanatus)
  • Tocalote (Centaurea melitensis)
  • Yellow Starthistle (Centaurea solstitialis)
  • Stinkwort (Dittrichia graveolens)
  • Coastal Heron's Bill (Erodium cicutarium)
  • Wild Geranium (Geranium dissectum)
  • Smooth Cat's Ear (Hypochaeris glabra)
  • Summer Cypress (Kochia scoparia)
  • Bur Clover (Medicago polymorpha)
  • Russian Thistle (Salsola tragus)
  • Charlock (Sinapis arvensis)
  • London Rocket (Sisymbrium irio)
  • Field Hedge Parsley (Torilis arvensis)
  • Puncture Vine (Tribulus terrestris)
  • Rose Clover (Trifolium hirtum)

Invasive Perennial Grasses

  • Pacific Bentgrass (Agrostis avenacea)
  • Redtop (Agrostis stolonifera)
  • Meadow Foxtail (Alopecurus pratensis)
  • Giant Reed (Arundo donax)
  • Purple False Brome (Brachypodium distachyon)
  • Andean Pampas Grass (Cortaderia jubata)
  • Pampas Grass (Cortaderia selloana)
  • Bermuda Grass (Cynodon dactylon)
  • Orchardgrass (Dactylis glomerata)
  • Perennial Veldt Grass (Ehrharta calycina)
  • Upright Veldt Grass (Ehrharta erecta)
  • Reed Fescue (Festuca arundinacea)
  • Italian Ryegrass (Festuca perennis)
  • Common Velvetgrass (Holcus lanatus)
  • Mexican Feathergrass (Nassella tenuissima)
  • Vasey's Grass (Paspalum urvillei)
  • Kikuyu Grass (Pennisetum clandestinum)
  • Fountaingrass (Pennisetum setaceum)
  • Harding Grass (Phalaris aquatica) 
  • Kentucky Bluegrass (Poa pratensis)
  • Ravennagrass (Saccharum ravennae)
  • Smilo Grass (Stipa miliacea var. miliacea)

Invasive Annual Grasses

  • Goatgrass (Aegilops triuncialis)
  • Slim Oats (Avena barbata)
  • Wild Oats (Avena fatua)
  • Rattlesnake Grass (Briza maxima)
  • Ripgut Brome (Bromus diandrus)
  • Soft Chess (Bromus hordeaceus)
  • Hairy Chess (Bromus japonicus)
  • Red Brome (Bromus rubens)
  • Downy Chess (Bromus tectorum)
  • Mat Sandbur (Cenchrus longispinus)
  • Dogtail Grass (Cynosurus echinatus)
  • Medusa Head (Elymus caput-medusae)
  • Rattail Six-weeks Grass (Festuca myuros)
  • Foxtail Barley (Hordeum murinum)
  • Annual Beardgrass (Polypogon monspeliensis)

 

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