When plants that evolved in one region of the globe are moved by humans to another region, a few of them flourish, crowding out native vegetation and the wildlife that feeds on it. Some invasives can even change ecosystem processes such as hydrology, fire regimes, and soil chemistry. These invasive plants have a competitive advantage because they are no longer controlled by their natural predators, and can quickly spread out of control. In California, approximately 3% of the plant species growing in the wild are considered invasive, but they inhabit a much greater proportion of the landscape. The list below includes California’s most invasive plants and provides links to additional information for each one.
- PAF = Plant Assessment Form with detailed information.
- Profile = Plant Profile webpage with additional links.
- CalWeedMapper = statewide map
(Source: California Invasive Plant Council – here)
- silver wattle (Acacia dealbata) – PAF, Profile, CalWeedMapper
- blackwood acacia (Acacia melanoxylon) – PAF, Profile, CalWeedMapper
- Russian knapweed (Acroptilon repens) – PAF, Profile, CalWeedMapper, Species ID Card
- barb goatgrass (Aegilops triuncialis) – PAF, Profile, CalWeedMapper, Species ID Card
- eupatory, croftonweed (Ageratina adenophora) – PAF, Profile, CalWeedMapper, Species ID Card
- Pacific bentgrass (Agrostis avenacea) – PAF, Profile, CalWeedMapper
- carpet bent (Agrostis stolonifera) – PAF, Profile, CalWeedMapper
- tree-of-heaven (Ailanthus altissima) – PAF, Profile, CalWeedMapper, Species ID Card
- camelthorn (Alhagi maurorum) – PAF, Profile, CalWeedMapper
- alligatorweed (Alternanthera philoxeroides) – PAF, Profile, CalWeedMapper
- European beachgrass (Ammophila arenaria) – PAF, Profile, CalWeedMapper
- sweet vernal grass (Anthoxanthum odoratum) – PAF, Profile, CalWeedMapper
- fertile capeweed (Arctotheca calendula) (fertile forms) – PAF, Profile, CalWeedMapper, Species ID Card
- capeweed (Arctotheca prostrata) – PAF, Profile, CalWeedMapper
- giant reed (Arundo donax) – PAF, Profile, CalWeedMapper, Species ID Card
- bridal creeper (Asparagus asparagoides) – PAF, Profile, CalWeedMapper
- onion weed (Asphodelus fistulosus) – PAF, Profile, CalWeedMapper, Species ID Card
- Australian saltbush (Atriplex semibaccata) – PAF, Profile, CalWeedMapper, Species ID Card
- slender oat (Avena barbata) – PAF, Profile, CalWeedMapper
- wild oats (Avena fatua) – PAF, Profile, CalWeedMapper
- five-horn smotherweed (Bassia hyssopifolia) – PAF, Profile, CalWeedMapper
- mediterranean lineseed (Bellardia trixago) – PAF, Profile, CalWeedMapper
- annual false-brome (Brachypodium distachyon) – PAF, Profile, CalWeedMapper, Species ID Card
- slender false-brome (Brachypodium sylvaticum) – PAF, Profile, CalWeedMapper
- black mustard (Brassica nigra) – PAF, Profile, CalWeedMapper
- field mustard (Brassica rapa) – PAF, Profile, CalWeedMapper
- Sahara mustard (Brassica tournefortii) – PAF, Profile, CalWeedMapper, Species ID Card
- rattlesnake grass (Briza maxima) – PAF, Profile, CalWeedMapper
- ripgut brome (Bromus diandrus) – PAF, Profile, CalWeedMapper
- soft chess (Bromus hordeaceus) – PAF, Profile, CalWeedMapper
- Japanese brome (Bromus japonicus) – PAF, Profile, CalWeedMapper
- red brome (Bromus madritensis ssp. rubens) – PAF, Profile, CalWeedMapper
- cheatgrass (Bromus tectorum) – PAF, Profile, CalWeedMapper
Species ID Card - European sea rocket (Cakile maritima) – PAF, Profile, CalWeedMapper
- Plumeless thistle (Carduus acanthoides) – PAF, Profile, CalWeedMapper, Species ID Card
- musk thistle (Carduus nutans) – PAF, Profile, CalWeedMapper, Species ID Card
- Italian thistle (Carduus pycnocephalus) – PAF, Profile, CalWeedMapper
- slenderflower thistle (Carduus tenuiflorus) – PAF, CalWeedMapper
- iceplant (Carpobrotus chilensis) – PAF, Profile, CalWeedMapper
- highway iceplant (Carpobrotus edulis) – PAF, Profile, CalWeedMapper
- woolly distaff thistle (Carthamus lanatus) – PAF, Profile, CalWeedMapper, Species ID Card
- purple starthistle (Centaurea calcitrapa) – PAF, Profile, CalWeedMapper, Species ID Card
- (Centaurea debeauxii)
- meadow knapweed (Centaurea jacea notho ssp. pratensis) – PAF, Profile, CalWeedMapper, Species ID Card
- diffuse knapweed (Centaurea diffusa) – PAF, Profile, CalWeedMapper, Species ID Card
- Malta starthistle (Centaurea melitensis) – PAF, Profile, CalWeedMapper
- yellow starthistle (Centaurea solstitialis) – PAF, Profile, CalWeedMapper, Species ID Card
- spotted knapweed (Centaurea stoebe ssp. micranthos) – PAF, Profile, CalWeedMapper, Species ID Card
- squarrose knapweed (Centaurea virgata var. squarrosa) – PAF, Profile, CalWeedMapper
- skeleton weed (Chondrilla juncea) – PAF, Profile, CalWeedMapper, Species ID Card
- Canada thistle (Cirsium arvense) – PAF, Profile, CalWeedMapper, Species ID Card
- bull thistle (Cirsium vulgare) – PAF, Profile, CalWeedMapper
- narriow-leafed iceplant (Conicosia pugioniformis) – PAF, Profile, CalWeedMapper, Species ID Card
- poison-hemlock (Conium maculatum) – PAF, Profile, CalWeedMapper, Species ID Card
- New Zealand cabbage tree (Cordyline australis) – PAF, Profile, CalWeedMapper
- pampasgrass (Cortaderia jubata) – PAF, Profile, CalWeedMapper, Species ID Card
- white pampasgrass (Cortaderia selloana) – PAF, Profile, CalWeedMapper, Species ID Card
- Cotoneaster (Cotoneaster franchetii) – PAF, Profile, CalWeedMapper, Species ID Card
- milkflower cotoneaster (Cotoneaster lacteus) – PAF, Profile, CalWeedMapper
- silverleaf cotoneaster (Cotoneaster pannosus) – PAF, Profile, CalWeedMapper, Species ID Card
- common brassbuttons (Cotula coronopifolia) – PAF, Profile, CalWeedMapper
- common hawthorn (Crataegus monogyna) – PAF, Profile, CalWeedMapper
- montbretia (Crocosmia x crocosmiiflora) – PAF, Profile, CalWeedMapper, Species ID Card
- common crupina (Crupina vulgaris) – PAF, Profile, CalWeedMapper
- artichoke thistle (Cynara cardunculus) – PAF, Profile, CalWeedMapper, Species ID Card
- Bermuda grass (Cynodon dactylon) – PAF, Profile, CalWeedMapper
- common houndstongue (Cynoglossum officinale) – PAF, Profile, CalWeedMapper
- annual dogtail (Cynosurus echinatus) – PAF, Profile, CalWeedMapper
- Scotch broom (Cytisus scoparius) – PAF, Profile, CalWeedMapper, Species ID Card
- Portugese broom (Cytisus striatus) – PAF, Profile, CalWeedMapper, Species ID Card
- orchard grass (Dactylis glomerata) – PAF, Profile, CalWeedMapper
- Cape-ivy (Delairea odorata) – PAF, Profile, CalWeedMapper
- tansy mustard (Descurainia sophia) – PAF, CalWeedMapper
- foxglove (Digitalis purpurea) – PAF, Profile, CalWeedMapper, Species ID Card
- wild teasel (Dipsacus fullonum) – PAF, Profile CalWeedMapper, Species ID Card
- Fullers teasel (Dipsacus sativus) – PAF, Profile, CalWeedMapper, Species ID Card
- stinkweed (Dittrichia graveolens) – PAF, Profile, CalWeedMapper, Species ID Card
- pride-of-Madeira (Echium candicans) – PAF, Profile, CalWeedMapper
- Brazilian egeria (Egeria densa) – PAF, Profile, CalWeedMapper
- purple veldtgrass (Ehrharta calycina) – PAF, Profile, CalWeedMapper, Species ID Card
- panic veldtgrass (Ehrharta erecta) – PAF, Profile, CalWeedMapper, Species ID Card
- long-flowered veldtgrass (Ehrharta longiflora) – PAF, Profile, CalWeedMapper, Species ID Card
- water hyacinth (Eichhornia crassipes) – PAF, Profile, CalWeedMapper
- Russian olive (Elaeagnus angustifolia) – PAF, Profile, CalWeedMapper
- medusahead (Elymus caput-medusae) – PAF, Profile, CalWeedMapper, Species ID Card
- devil’s thorn (Emex spinosa) – PAF, Profile, CalWeedMapper, Species ID Card
- Spanish heath (Erica lusitanica) – PAF, Profile, CalWeedMapper, Species ID Card
- redstem filaree (Erodium cicutarium) – PAF, Profile, CalWeedMapper
- red gum (Eucalyptus camaldulensis) – PAF, Profile, CalWeedMapper
- blue gum (Eucalyptus globulus) – PAF, Profile, CalWeedMapper
- eggleaf spurge (Euphorbia oblongata) – PAF, Profile, CalWeedMapper, Species ID Card
- carnation spurge (Euphorbia terracina) – PAF, Profile, CalWeedMapper, Species ID Card
- leafy spurge (Euphorbia virgata) – PAF, Profile, CalWeedMapper
- Japanese knotweed (Fallopia japonica) – PAF, Profile, CalWeedMapper, Species ID Card
- giant knotweed (Fallopia sachalinensis) – PAF, Profile, CalWeedMapper, Species ID Card
- coarse fescue (Festuca arundinacea) – PAF, Profile, CalWeedMapper
- red-tailed fescue (Festuca myuros) – PAF, Profile, CalWeedMapper
- Italian ryegrass (Festuca perennis) – PAF, Profile, CalWeedMapper
- edible fig (Ficus carica) – PAF, Profile, CalWeedMapper
- sweet fennel (Foeniculum vulgare) – PAF, Profile, CalWeedMapper, Species ID Card
- treasure flower (Gazania linearis) – PAF, Profile, CalWeedMapper, Species ID Card
- bridal veil broom (Genista monosperma) – PAF, Profile, CalWeedMapper
- French broom (Genista monspessulana) – PAF, Profile, CalWeedMapper, Species ID Card
- cutleaf geraniium (Geranium dissectum) – PAF, Profile, CalWeedMapper
- crown daisy (Glebionis coronaria) – PAF, Profile, CalWeedMapper, Species ID Card
- sweetgrass (Glyceria declinata) – PAF, Profile, CalWeedMapper, Species ID Card
- Halogeton (Halogeton glomeratus) – PAF, Profile, CalWeedMapper
- English ivy and Algerian ivy (Hedera helix, H. canariensis) – PAF, Profile, CalWeedMapper
- licorice plant (Helichrysum petiolare) – PAF, Profile, CalWeedMapper, Species ID Card
- bristly ox-tongue (Helminthotheca echioides) – PAF, Profile, CalWeedMapper
- short-pod mustard (Hirschfeldia incana) – PAF, Profile, CalWeedMapper
- common velvet grass (Holcus lanatus) – PAF, Profile, CalWeedMapper
- Mediterranean barley (Hordeum marinum, H. murinum) – PAF, Profile, CalWeedMapper, CalWeedMapper
- water thyme (Hydrilla verticillata) – PAF, Profile, CalWeedMapper
- Canary Island St. Johnswort (Hypericum canariense) – PAF, Profile, CalWeedMapper, Species ID Card
- St. John’s Wort (Hypericum perforatum) – PAF, Profile, CalWeedMapper, Species ID Card
- smooth catsear (Hypochaeris glabra) – PAF, Profile, CalWeedMapper
- common cat’s-ear (Hypochaeris radicata) – PAF, Profile, CalWeedMapper
- English holly (Ilex aquifolium) – PAF, Profile, CalWeedMapper
- pale yellow iris (Iris pseudacorus) – PAF, Profile, CalWeedMapper, Species ID Card
- dyer’s woad (Isatis tinctoria) – PAF, Profile, CalWeedMapper, Species ID Card
- kochia (Kochia scoparia) – PAF, Profile, CalWeedMapper
- hairy whitetop (Lepidium appelianum) – PAF, Profile, CalWeedMapper
- hoary cress (Lepidium chalepense) – PAF, Profile, CalWeedMapper, Species ID Card
- white-top (Lepidium draba) – PAF, Profile, CalWeedMapper, Species ID Card
- perennial pepperweed (Lepidium latifolium) – PAF, Profile, CalWeedMapper, Species ID Card
- ox-eye daisy (Leucanthemum vulgare) – PAF, Profile, CalWeedMapper, Species ID Card
- South American spongeplant (Limnobium laevigatum) – PAF, Profile, CalWeedMapper
- Algerian sea lavendar (Limonium ramosissimum ssp. provinciale) – PAF, Profile, CalWeedMapper, Species ID Card
- broad-leaved toadflax (Linaria dalmatica ssp. dalmatica) – PAF, Profile, CalWeedMapper, Species ID Card
- Yellow toadflax (Linaria vulgaris) – PAF, Profile, CalWeedMapper, Species ID Card
- sweet alyssum (Lobularia maritima) – PAF, Profile, CalWeedMapper
- creeping waterprimrose (Ludwigia hexapetala) – PAF, Profile, CalWeedMapper
- creeping waterprimrose (Ludwigia peploides) – PAF, Profile, CalWeedMapper
- hyssop loosestrife (Lythrum hyssopifolium) – PAF, Profile, CalWeedMapper
- purple loosestrife (Lythrum salicaria) – PAF, Profile, CalWeedMapper, Species ID Card
- white horehound (Marrubium vulgare) – PAF, Profile, CalWeedMapper
- California burclover (Medicago polymorpha) – PAF, Profile, CalWeedMapper
- pennyroyal (Mentha pulegium) – PAF, Profile, CalWeedMapper, Species ID Card
- common iceplant (Mesembryanthemum crystallinum) – PAF, Profile, CalWeedMapper
- false sandalwood (Myoporum laetum) – PAF, Profile, CalWeedMapper
- common forget-me-not (Myosotis latifolia) – PAF, Profile, CalWeedMapper
- parrotfeather (Myriophyllum aquaticum) – PAF, Profile, CalWeedMapper
- spike watermilfoil (Myriophyllum spicatum) – PAF, Profile, CalWeedMapper
- tree tobacco (Nicotiana glauca) – PAF, Profile, CalWeedMapper
- olive (Olea europaea) – PAF, Profile, CalWeedMapper
- foxtail restharrow (Ononis alopecuroides) – PAF, Profile, CalWeedMapper
- scotch thistle (Onopordum acanthium) – PAF, CalWeedMapper, Species ID Card
- buttercup oxalis (Oxalis pes-caprae) – PAF, Profile, CalWeedMapper
- yellow glandweed (Parentucellia viscosa) – PAF, Profile, CalWeedMapper
- kikuyugrass (Pennisetum clandestinum) – PAF, Profile, CalWeedMapper
- purple fountain grass (Pennisetum setaceum) – PAF, Profile, CalWeedMapper, Species ID Card
- bulbous canarygrass (Phalaris aquatica) – PAF, Profile, CalWeedMapper
- Canary Island date palm (Phoenix canariensis) – PAF, Profile, CalWeedMapper
- common pokeweed (Phytolacca americana) – PAF, Profile, CalWeedMapper, Species ID Card
- buckhorn plantain (Plantago lanceolata) – PAF, Profile, CalWeedMapper
- Kentucky bluegrass (Poa pratensis) – PAF, Profile, CalWeedMapper
- annual beardgrass (Polypogon monspeliensis) – PAF, CalWeedMapper
- curly-leaved pondweed (Potamogeton crispus) – PAF, Profile, CalWeedMapper
- cherry plum (Prunus cerasifera) – PAF, Profile, CalWeedMapper
- narrowleaf firethorn, scarlet firethorn (Pyracantha angustifolia, crenulata, coccinea) – PAF, Profile, CalWeedMapper
- creeping buttercup (Ranunculus repens) – PAF, Profile, CalWeedMapper
- wild radish (Raphanus sativus) – PAF, Profile, CalWeedMapper
- castor bean (Ricinus communis) – PAF, Profile, CalWeedMapper
- black locust (Robinia pseudoacacia) – PAF, Profile, CalWeedMapper
- Himalayan blackberry (Rubus armeniacus) – PAF, Profile, CalWeedMapper, Species ID Card
- sheep sorrel (Rumex acetosella) – PAF, Profile, CalWeedMapper
- curly dock (Rumex crispus) – PAF, Profile, CalWeedMapper
- hairy oat grass (Rytidosperma penicillatum) – PAF, Profile, CalWeedMapper
- hardy pampas grass (Saccharum ravennae) – PAF, Profile, CalWeedMapper
- barbwire Russian thistle (Salsola paulsenii) – PAF, Profile, CalWeedMapper
- glasswort (Salsola soda) – PAF, Profile, CalWeedMapper
- Russian thistle (Salsola tragus) – PAF, Profile, CalWeedMapper
- Mediterranean sage (Salvia aethiopis) – PAF, Profile, CalWeedMapper
- giant salvinia (Salvinia molesta) – PAF, Profile, CalWeedMapper
- bouncing betty (Saponaria officinalis) – PAF, Profile, CalWeedMapper
- California pepper tree (Schinus molle) – PAF, Profile, CalWeedMapper
- Brazilian pepper tree (Schinus terebinthifolius) – PAF, Profile, CalWeedMapper
- Mediterraneangrass, split-grass (Schismus arabicus, S. barbatus) – PAF, Profile, CalWeedMapper
- cutleaf fireweed (Senecio glomeratus) – PAF, Profile, CalWeedMapper
- tansy ragwort (Senecio jacobaea) – PAF, Profile, CalWeedMapper
- scarlet wisteria (Sesbania punicea) – PAF, Profile, CalWeedMapper, Species ID Card
- milk thistle (Silybum marianum) – PAF, Profile, CalWeedMapper
- wild mustard (Sinapis arvensis) – PAF, Profile, CalWeedMapper
- London rocket (Sisymbrium irio) – PAF, Profile, CalWeedMapper
- smooth cordgrass and hybrids (Spartina alterniflora x foliosa, S. alterniflora) – PAF, Profile, CalWeedMapper
- English cordgrass (Spartina anglica) – PAF, Profile, CalWeedMapper
- dense-flowered cordgrass (Spartina densiflora) – PAF, Profile, CalWeedMapper
- Salt marsh hay (Spartina patens) – PAF, Profile, CalWeedMapper
- Spanish broom (Spartium junceum) – PAF, Profile, CalWeedMapper, Species ID Card
- cape ricegrass (Stipa capensis) – PAF, Profile, CalWeedMapper
- tropical needlegrass (Stipa manicata) – PAF, Profile, CalWeedMapper
- smilo grass (Stipa miliacea var. miliacea) – PAF, Profile, CalWeedMapper
- smallflower tamarisk (Tamarix parviflora) – PAF, Profile, CalWeedMapper, Species ID Card
- athel pine (Tamarix aphylla) – PAF, Profile, CalWeedMapper, Species ID Card
- saltcedar, tamarisk (Tamarix ramosissima, T. gallica, T. chinensis) – PAF, Profile, CalWeedMapper, Species ID Card
- common tansy (Tanacetum vulgare) – PAF, Profile, CalWeedMapper
- New Zealand spinach (Tetragonia tetragonioides) – PAF, Profile, CalWeedMapper
- hedgeparsley (Torilis arvensis) – PAF, Profile, CalWeedMapper
- Chinese tallow trees (Triadica sebifera) – PAF, Profile, CalWeedMapper
- rose clover (Trifolium hirtum) – PAF, Profile, CalWeedMapper
- common gorse (Ulex europaeus) – PAF, Profile, CalWeedMapper, Species ID Card
- Japanese kelp (Undaria pinnatifida) – PAF, Profile, CalWeedMapper
- common mullein (Verbascum thapsus) – PAF, Profile, CalWeedMapper
- periwinkle (Vinca major) – PAF, Profile, CalWeedMapper, Species ID Card
- Mexican fan palm (Washingtonia robusta) – PAF, Profile, CalWeedMapper
- Watsonia (Watsonia meriana) – PAF, Profile, CalWeedMapper, Species ID Card
- calla lily (Zantedeschia aethiopica) – PAF, Profile, CalWeedMapper
- dwarf eelgrass (Zostera japonica) – PAF, Profile, CalWeedMapper
- zz_Draft_Wards weed (Carrichtera annua) – PAF
- zz_Draft_boneseed (Chrysanthemoides monilifera ssp. monilifera) – PAF
- zz_Draft_old man’s beard (Clematis vitalba) – PAF
- zz_Draft_taro root (Colocasia esculenta) – PAF
- zz_Draft_little robin (Geranium purpureum) – PAF
- zz_Draft_glossy privet (Ligustrum lucidum) – PAF
- zz_Draft_European sea lavendar (Limonium duriusculum) – PAF
- zz_Draft_slenderleaf iceplant (Mesembryanthemum nodiflorum) – PAF
- zz_Draft_puncturevine (Tribulus terrestris) – PAF
- zz_Draft_desert knapweed (Volutaria tubuliflora) – PAF