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a SOLV volunteer romoves ivy from a tree at Fields Creek, saving the tree
photo© Lory Duralia

Western North American wildlife has been challenged by introduced species since the pioneers cultivated the land. We continue to disrupt habitats that had bargained for centuries to achieve an equilibrium and support a rich diversity of native plants and animals when we introduce and encourage "exotic", or non-native, species that are invasive. Spreading out and inhabiting natural spaces, they often take over.

The bullfrog has displaced native amphibians in many places; since introduced (for frog legs - bon apetit!), it has increased in numbers sufficient to threaten native populations of frogs and turtles. Red-legged frog, western pond turtle, and painted turtle populations have declined because of predation by bullfrogs, who eat tadpoles and eggs, in addition to habitat loss and degradation. Here at the nursery, a bullfrog threatened our native red-legged frogs and tree frogs, so we caught it in a trap (they like cat food and sardines), and banished it! You can tell a bullfrog by its habit of making a "eeeeeeeee!" sound when it jumps; native Pacific tree frogs, on the other hand, serenade us with their familiar "ribit" throughout the evening and night hours every spring during mating season, and red-legged frogs communicate under water.

Many non-native plants have invaded greenspaces and choked out native plants. Buddleia (butterfly bush) planted in gardens spreads by seed and quickly takes over. It has recently been added to the Portland nuisance plant list (below) because of its aggressive nature. Good substitutes for buddleia include Ceanothus thrysiflorus, a beautiful native evergreen with gorgeous blue flowers in spring, and any of our native Spireas. See our butterfly page for more suggestions! Other invasive "exotics" include English ivy, which competes with native vegetation in many woodlands, and wins, often killing trees in its path, and Canary reed grass, which has choked out native grasses and undergrowth in open spaces all over our region.

There are many examples of introduced plants and animals that threaten native species, and much every gardener can do. Do not plant invasive exotic species, whose seeds are often spread by birds and wind to habitats outside your own garden. Volunteer to eradicate invasive species with an environmental organization - there are many annual "ivy pulls" in a variety of public spaces every year. And of course, plant native! to renew declining species and feed native wildlife. Remember to plant natives densely when removing invasive exotics from your land, so that they have a chance to out-compete re-emerging nuisance plants.

The city of Portland's natural resource protection program aims to educate the public about our natural heritage and "promote the continued viability and diversity of indigenous plant and animal communities". Portland developed a 'Native Plant List' to help people choose appropriate species for planting, as well as a 'Nuisance Plant List' and 'Prohibited Plant List', which I have included below. Nuisance plants may be native, naturalized or exotic, and they are considered a nuisance because of their tendency to dominate plant communities or because they are harmful to humans. Prohibited plants are those the city prohibits from use in all reviewed landscaping situations within the city limits. The plants on this list pose a serious threat to the health and vitality of native plant and animal communitities; even if the regulations do not apply to you, you can use the list as a guide to responsible landscaping. In addition, the Oregon Department of Agriculture Noxious Weed List can be found online at: oda.state.or.us/Plant/weed_control/index.html

Prohibited Plants
Scientific Name Common Name
Cytisus scopariusScot's Broom
Hedera helixdEnglish Ivy
Lythrum salicariaPurple Loosestrife
Phalaris arundinacaeaReed Canarygrass
Rubus discolorHimalayan Blackberry

Nuisance Plants
Scientific NameCommon Name
Acroptilon repensRussian knapweed
Aegopodium podagraria and variegated varietiesGoutweed
Agropyron repensQuack grass
Alopecuris pratensisMeadow foxtail
Anthoxanthum odoratumSweet vernalgrass
Arctium minusCommon burdock
Arrhenatherum elatiusTall oatgrass
Betula pendula lacinataCutleaf birch
Brachypodium sylvaticumFalse brome
Bromus diandrusRipgut
Bromus hordeaceusSoft brome
Bromus inermisSmooth brome-grasses
Bromus japonicusJapanese brome-grass
Bromus sterilisPoverty grass
Bromus tectorumCheatgrass
Buddleia davidii Butterfly bush
Callitriche stagnalisPond water starwort
Cardaria drabaHoary cress
Carduus acanthoidesPlumeless thistle
Carduus nutansMusk thistle
carduus pycnocephalusItalian thistle
Caraduus tenufoliusSlender flowered dthistle
Centaurea biebersteiniiSpotted knapweed
Centaurea diffusaDiffuse knapweed
Caentaurea jaceaBrown knapweed
Centauarea pratensisMeadow knapweed
Chicorum intybusChicory
Chondrilla junceaRush skelotonweed
Dipsaucus fullonumCommon teasel
Euphorbia lathyrusMole plant
Festuca arundinaceaTall fescue
Foeniculum vulgareFennel
Galium odoratumSweet woodruff
Geranium lucidumShining geranium
Geranium robertianumRobert geranium
Geum urbanumEuropean avens
Heracleum mantegazzianumGiant hawkweed
Hieracium aurantiacum
Hieracaium cespitosumYellow hawkweed
Hieracium laevigatumSmooth hawkweed
Hieracium pilosellaMouse-ear hawkweed
Holcus lanatusVelvet grass
Houttuynia cordataChameleon plant
Hydrilla verticillataHydrilla
Hypericum perforatumSt. John's Wort
Hypocharis radicataSpotted cat's ear
Ilex aquafoliumEnglish holly
Impatiens glanduliferaPolicemen's helmet
Iris pseudacorusYellow flag
Juncus effusus v. effususEuropean soft rush
Laburnum watereriGolden chain tree
Lactuca muralisWall lettuce
Lactuca serriolaPrickly lettuce
Lamium maculatumWhite Nancy
Lapsana communisNipplewort
Lemna minorDuckweed, Water lentil
Leontodon autumnalisFall dandelion
Leucanthemum vulgareOxeye daisy
Ligustrum vulgarePrivet
Linaria dalmatica ssp. dalmaticaDalmation toadflax
Linaria vulgarisYellow toadflax
Lolium multiflorumAnnual ryegrass
Lotus corniculatusBird's foot trefoil
Ludwigia hexapetalaWater primrose
Lunaria annuaMoney plant
Lychnis albaWhite campion
Lysimachia nummulariaCreeping jenny
Lythrum portulaSpatula leaf purslalne
Melilotus albaSweetclover
Melilotus officinalisYellow sweetclover
Melissa officianalisLemon balm
Mentha pulegiumPenny royal
Myriophyllum aquaticumParrots feather
Myriophyllum spicatumEurasian watermilfoil
Nymphaea odorataFragrant water lily
Onopordum acanthiumScotch thistle
Panicum capillareWitchgrass
Parentucellia viscosaParentucellia
Paulownia tomentosaPrincess tree
Phalaris aquaticaHarding grass
Phleum pratensisTimothy
Phragmites australis
Phytolacca americanaPokeweed
Poa annuaAnnual bluegrass
Polygonum aviculareDoorweed
Polygonum coccineumWater smartweed
Polygonum convolvulusClimbing bindweed
Polygonum cuspidatumJapanese knotweed
Polygonum polystachymumHimalayan knotweed
Polygonum sachalinenseGiant knotweed
Populus albaWhite poplar
Potamogeton crispusCurly leaf pondweed
Prunus avium (except cultivars and varieties)Sweet cherry
Prunus laurocerasusEnglish, Portugese laurel
Pueraria lobataKudzu
Ranunculus ficariaLesser celandine
Ranunculus repensCreeping buttercup
Rhus diversilobaPoison oak
Robinia pseudoacacia (except cultivars and varieties)Black locust
Rorippa nasturtium-aquaticumEuropean watercress
Rosa eglanteriaSweet briar
Rosa multifloraMultiflora rose
Rubus laciniatusEvergreen blackberry
Rumex acetosellaRed sorrel
Rumex crispusCurly dock
Secale ceraleCultivated rye
Senecio jacobaeaTansy ragwort
Silene albaWhite campion
Sisyrimbium officinaleHedge mustard
Solanum dulcamaraBlue bindweed
Solanum nigrumGarden nightshade
Solanum sarrachoidesHairy nightshade
Solybum marianumBlessed milk thistle
Sonchus arvensis ssp. arvensisPerennial sowthistle
Sorbus aucuparia (except cultivars and varieties)European mountain ash
Sorghum halepenseJohnson grass
Taeniatherum caput-medusaMedusahead
Tanacetum vulgareCommon tansy
Taraxacum officinaleCommon dandelion
Trifolium arvenseHare's foot clover
Trifolium hybridumAlsike clover
Trifolium repensWhite clover
Trifolium subterraneumSubterraneum clover
Ulex europaeusGorse
Ulmus pumilaSiberian elm
Utricularia inflataSwollen bladderwort
Utricularia vulgarisCommon bladderwort
Verbascum blattariaMoth mullein
Verbascum thapsusMullein
Verabena bonariensisTall verbena
Vicia craccaTufted vetch
Vicia sativaVetch
Viciaa villlosaHairy vetch
Vinca majorPeriwinkle (large leaf)
Vinca minorPeriwinkle (small leaf)
Vulpia myuros [Festuca myuros]Rat-tailed fescue
Xanthium spinoseumSpiny cocklebur
various generaBamboo sp.
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