Selected Invasive

Plants of Alaska

2004

United States Department of

Agriculture

Forest Service, Alaska Region R10-TP-130B

Produced by State & Private Forestry, Forest Health Protection

When trying to identify an unknown plant, color photos often help. This pocket guide provides a selection of invasive plants found across Alaska today. This booklet is not intended to take the place of more comprehensive reference guides, but to help those unfamiliar with these species to begin to recognize them, as the first step towards taking action.

Non-native invasive plants displace native vegetation, degrade wildlife habitat, and negatively affect human health, the economy, and the environment. Factors such as geographic isolation and harsh winters have protected Alaska from large-scale invasive plant infestations in the past. Recently, however, some of the most harmful noxious weeds of the lower 48 states have begun to grow and spread in Alaska.

Many of the invasive plants featured in this booklet have been responsible for significant economic losses and environmental damage across North America over the past two centuries. Other species featured here (Siberian peashrub and European bird cherry) have been dependable components of Alaska’s urban landscape, but were included because they have recently been observed spreading aggressively into Alaskan wildlands and natural areas.

There are many ways invasive plants are introduced to Alaska. Seeds and plant parts can travel in the root balls of nursery stock, in animal feed, tires, recreational equipment, or as components of wildflower seed mixes. Movement of people and equipment within natural areas and site-disturbing projects, such as road-building and construction, can create inroads for invasive plants.

Alaskans have the chance to prevent invasive plant infestations before they become so widespread that control is costly and eradication impossible. This invasive plant booklet is designed to assist with identifying some of the most problematic species that are now moving along the roads, streams and beaches of Alaska. Thank you for doing your part to insure that these invasive plant species, and others like them, do not spread into Alaska's wildlands.

Photos provided by the Forest Service or the UAF Cooperative Extension Service unless noted.

UNIVERSITY OF ALASKA

FAIRBANKSCollege of Rural Alaska

Cooperative Extension Service

NATIONALPARK

SERVICE

Departmentof the Interior

Spotted Knapweed on Turnagain Arm

In Alaska we are concentrating on prevention, early detection, and rapid response.

Prevention:

Keeping these invasive plant species from becoming established in Alaska is the highest priority. This booklet is a tool to help identify some of the species of greatest concern in Alaska.

Early Detection & Rapid Response:

Not only is it important to recognize these plants, but it is imperative that we find small infestations before they become too difficult to control. For example, spotted knapweed has been found five times within Alaska, but luckily these sites were discovered when the populations were less than 100 plants each.

The Alaska Soil and Water Conservation Districts are in the process of forming “Cooperative Weed Management Areas” (CWMAs) across the state. The CWMAs will be actively involved in the detection, monitoring, and treatment of problematic invasive plant populations.

For additional information about invasive plants in Alaska: Contact your local UAF Cooperative Extension Service office or

appropriate local land management agency.

Or visit:

http://www.uaf.edu/coop-ext http://www.fs.fed.us/r10/spf/fhp/ http://www.cnipm.org/index.html

To view or contribute to the state-wide database of exotic plants:http://akweeds.uaa.alaska.edu/akweeds2.html

This document was produced by:Michael Shephard, USDA Forest Service, State & Private Forestry

Tom Huette, USDA Forest Service, State & Private Forestry Jamie M. Snyder, UAF Cooperative Extension Service

(see back pages for index)

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 1

Canada Thistle (Cirsium arvense) Sunflower Family

• Aperennialthatgrowstofivefeettallwitherect,ridged,branchingstems.Leavescurled,wavy,oblong,alternateonstemwithwoollyhairsonunderside.Leavesarisedirectlyfromthestemwithoutadistinctleafstalk.Flowersarepurple-pinkinclustersattheendsofbranches.

• Formscoloniesviaanextensivehorizontalandverticalrootsystem;caneventuallycoveracres.Alsospreadsbywind-blownseeds.Youngplantsappearasbasalrosettesthatboltinlatesummer.Growsinfields,pastures,forests,andalongroadsides,ditches,andriverbanks.

• Restrictsrecreationallanduse,scratchesandinfectsanimalskin,andproducesallelopathicchemicalstosuppresssurroundingvegetation.Verydifficulttoeradicateonceestablished.

Canada Thistle (Cirsium arvense) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 3

Bull Thistle (Cirsium vulgare) Sunflower Family

• Biennialerectplantrisesfromafleshytaproot.Alarge,flatrosetteformsinthefirstyear,andflowersandstemselongateinthesecondyear.Stemgrows2to5feettallwithmanyspreadingbranches.Leaveshairyandpricklyonupperside,andcottonyunderneath.Stemshaveirregularspiny“wings.”Flowerheadsare1.5to2inches,urnshaped,purplerayflorets.Bractsunderflowersarefleshyandtippedwithspines.

• Foundondisturbedsites,roadsides,andriparianareas.FoundinAnchorage,Haines,POWislandthusfar.

• Restrictsrecreationallanduse,decreaseslandvalue,andcompeteswithnativevegetationforwater,space,andlight.

Bull Thistle (Cirsium vulgare) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 5

Oxeye Daisy (Leucanthemum vulgare) Sunflower Family

• Ashort-livedshowyperennialthatspreadsvegetativelybyrhizomesorfromseeds.Headssolitaryattheendsofbranches,consistingofrayanddiscflowers.Whiterayflorets0.5to1inchlong.Yellowdiscs0.5to1inchacross.Leaveshairlesstosparselyhairy,alternatealongthestem,becomingprogressivelysmallertowardsthetop,oblanceolate,withcrenatetolobedmargins.Upperleavestoothed,lackingapetiole.

• Commononroadsides,disturbedareas,beachmeadows,andlandscapedareas.Frequentlyacomponentofwildflowerseedmixes.Formsdensecolonies,isunpalatabletograzinganimalsandinsects,andhostsseveralplantviruses.Heavyinfestationscancausesoilerosion.

Oxeye Daisy (Leucanthemum vulgare) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 7

Spotted Knapweed (Centaurea biebersteinii) Sunflower (or C. maculosa) Family

• Biennialorshort-livedperennial.Plantsgrowtothreefeettallfromastouttaproot.Basalrosetteshavedeeplylobedgray-greenleaves.Flowerheadssolitaryattheendsofbranches.Involucralbractsbeneathflowersarestiffandtoppedwithdarkcomb-likefringegivingaspottedappearance.Flowerheadspink-purple,consistingofrayfloretsonly,solitaryattheendofstembranches.

• Spreadsonlybyseeds.Adaptedtowell-drainedsoils.Seedsdispersedneartheparentplantortransportedbypeople,wildlife,vehicles,andinsoil,cropseed,andcontaminatedhay.LookforthisplantalongroadsidesinAlaska.FoundinAnchorage,Haines,ValdezandPOWislandthusfar.

• ResponsibleformillionsofdollarsineconomiclossandenvironmentaldamageinthewesternUnitedStates.

Spotted Knapweed (Centaurea biebersteinii) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 9

Orange Hawkweed (Hieracium aurantiacum) Sunflower Family

• Aperennialwithcolorfulorange-redflowersaboutoneinchindiameter.Flowerheadsareredontheedgesandorangeinthecenter.Flowersconsistofrayfloretsonlywithnotcheduppermargins.Leavesclusteredinabasalrosette.Afewsmallleavesmaybefoundonthe6to8inchlongstem,butoftenstemsremainleafless.Leavesarecoveredwithsoftwhitehairs.Stemshaveshorterdarkcoloredhairs.Leavesaredarkergreenontheuppersurfacethanthelowersurface.Stems2to12inches,occasionallygrowingtotwofeet.Milkyjuiceproducedbyleavesandstems.

• Spreadsbystolons,rhizomes,andseed.Afavoriteflowerofunwarygardenersandwildflowerenthusiasts.Foundalongroads,riparianareasandbeaches.Movesintoforbmeadowswhereitspreadsaggressively.Formsdensemats,crowdingoutnativeplants.

Orange Hawkweed (Hieracium aurantiacum) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 11

Non-Native Sunflower Family Yellow-flowered Hawkweeds

Meadow Hawkweed (Hieracium caespitosum)Mouse-ear Hawkweed (H. pilosella)Narrowleaf Hawkweed (H. umbellatum)

• Bothnativeandnon-nativespeciesofhawkweedexistinAlaska.NativeAlaskanhawkweedslackstolons,havebranchedstemswithmanyleaves,andgenerallyarefoundinhigh-elevationmeadows.

• Mouse-earhawkweediseasilyidentifiedbyits solitaryyellowflower.

• Similarinappearancetoorangehawkweed,meadowhawkweedgrowstothreefeet,itsstemcoveredincoarseblackgland-tippedhairs,andbearingmultipleyellowflowers.

• Narrowleafhawkweedhashairyleaveswithserratedmargins.Non-Native Yellow-flowered Hawkweeds Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 13

Narrowleaf Hawksbeard (Crepis tectorum) Sunflower Family

Related Species: Smooth Hawksbeard (Crepis capillaris), is another invasive species.

• Annualorwinterannualto3feettall.Basalleavesarestalkedandlance-shapedwithmarginsvaryingfromnumerousbackward-pointingteethtodeeplylobed.Stemleavesclaspthestem.Leafmarginsareoftencurledbacktowardsthemidrib.Bractsbelowdandelion-likeyellowrayflowersaresmooth,lackinghairs.

• Oftenfoundondisturbedsoil;wasteplaces,riverbars,orroadsides.Thrivesindry,coarsesoil.Competeswithseedlings,forages,cerealsandoilseeds.Themostseriousinfestationsofthisweedoccurinweakcropstands.Spreadsintoriparianareas.

Narrowleaf Hawksbeard (Crepis tectorum) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 15

Hairy Catsear (Hypochaeris radicata) Sunflower Family

Similar Species: Fall Hawkbit (Leontodon autumnalis), is a similar-looking exotic species.

• Perennialherbwithabasalrosetteofdandelion-shapedleaves.Similarinappearancetodandelion,butcangrowto2feet.Leavesaredenselyhairyonbothsides.Noleavesonstems.Severalsimpleorbranchedstems6to24inchestall.Yellowflowerheads,oftenseveralheadsperstem.

• Growsinmeadows,gardens,roadsides,andwasteplaces.EspeciallycommoninsouthernSoutheastAlaska.

Hairy Catsear (Hypochaeris radicata) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 17

Perennial Sowthistle (Sonchus arvensis) Sunflower Family

Related Species: Common Sowthistle (Sonchus oleraceus)

• Perennialwithflowersandleavessimilartothedandelion.Plantstofourorfivefeettall.Flowerheadsare1to2inchesacross.Longstemsarisefromabasalrosetteofdandelion-likeleaves.Stemsarebranchedonlyatthetop.Basalandstemleaveshavepricklymargins.Leavesonthestemarelessnumerous,andclaspthestemsatthebase.Plantsexudeamilkysapwhenbroken.Bractsbelowflowershavenumerousglandtippedhairs

• Commonlyfoundinwasteareas,meadows,woods,lawns,roadsides,beaches,ditches,andriverandlakeshores.Candrasticallyreducecropyieldsinagriculturalareasbycompetingwithdesiredplantsfornutrients.

Perennial Sowthistle (Sonchus arvensis) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 19

Common Tansy (Tanacetum vulgare) Sunflower Family

• Perennial,spreadsbyseedandbyshortrhizomes,formingdenseclumps.Flat-toppedclustersofbutton-likeyellowflowers.Numerouscompositeflowerheads(20to200perplant).Headscomposedofdiscfloretsonly-flowerheadswithoutpetals.Uprightstemsoftenpurplish-redanddottedwithglands.Leavesalternateanddeeplydividedintonarrowindividualleaflets,givingafeatheryappearance.Plantsgrowtofivefeettall.Strongodorreminiscentofcreosote.

• Thrivesindisturbedhabitatsinfullsun.Foundonroadsides,riverandstreambanks,andbeachmeadows.Mildlytoxictograzinganimals.

Common Tansy (Tanacetum vulgare) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 21

Tansy Ragwort (Senecio jacobaea) Sunflower Family

• Short-livedperennialwithonetoseveralstemsarisingfromataproot.Theplantgrows1to4feettall.Leavesdeeplycut.Basalleavesstalked2to8incheslong.Leavesbecomesmallerandpetiolesbecomeshortermovingupthestem.Flowerheadsborneinterminalclusters,headsconsistofyellowrayanddiscflorets.Rayfloretsnumber10to13.Petalsare0.25to0.5incheslong.

• Formsalow-growingrosetteinthefirstyear.Foundinwasteplaces,roadsides,clearcuts,meadows.Containsatoxiccompoundresponsibleforconsiderablelivestockmortality.

Tansy Ragwort (Senecio jacobaea) Sunflower Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 23

Western Salsify (Tragopogon dubius) Sunflower Family

• Biennialoroccasionallyannual,growing1to3feettall,withalong,stouttaproot.Thehollowstem,andlong,narrowgrass-likeleavescontainamilkywhitejuice.Stemsareswollenimmediatelybelowyellowrayflowers.Bractsaredistinctlylongerthantheyellowflowerpetals.Dandelion-likeseedsarewinddispersed.Juvenileplantsresembleshootsofgrass.Flowerheadsopenandpointtowardthesuninthemorning,followingituntilmiddaybeforeclosingagain.

• Occursalongroadsidesanddisturbedsites.AlargepopulationhasbecomeestablishedalongtheTurnagainArmsegmentoftheSewardHighway,andisspreadingrapidlydespitecontrolefforts.

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Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 25

Japanese Knotweed Buckwheat Family (Polygonum cuspidatum)

• Anherbaceousperennialthatformsextremelydensestands,shadingoutcompetingvegetation.Stemsto10feettall,hollow,bamboo-likewiththickenednodeswheretheleafstalksmeetthestem.Leavesbroadlyoval,to6incheslong,withshortpetioles.Branchedspraysofsmallwhitetogreenish-whiteflowersinlateAugust/September.Giantknotweedissimilarinappearancebuthasmuchlargerleavesandstems.

• Herbaceousperennial.Diesback,turningbrightyellowbeforedroppingleavesinthefall.Reproducesfromextensivespreadingrhizomesorbroken-offpiecesofstem.

• Foundonroadsides,streambanks,andbeachmeadows.Clogswaterwaysandlowersqualityofhabitatforwildlife,fish,andtheinsectsonwhichfishdepend.

Japanese Knotweed Buckwheat Family (Polygonum cuspidatum)

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 27

Garlic Mustard (Alliaria petiolata) Mustard Family

• Herbaceousbiennialplant.Stronggarlicodorwhencrushed.Firstyearplantsarerosettesofdarkgreenkidneyshapedleavesarisingfromacommonbasewithdistinctleafveinsandscallopededgesto4inchesindiameter.Secondyearplantswithfewtoseveral-branchedstemsto3feettall.Secondyearplantshavealternatetriangularleaves,decreasinginsizetowardthetopofthestem.Flowerswhite,0.25inchesindiameter,withfourpetals.PlantsflowerinApril-JunewithseedsproducedJune-August.Seeds8to10/pod,shiny-black,cylindrical.Verytolerantofcooltemperaturesandlowlight.

• Thrivesonthemoist,shadedsoilofriverfloodplains,forests,roadsides,edgesofwoods,trails,andforestopenings.Dominatestheunderstoryinforestedareas.Reducesforagesitesfordeerandothergrazingwildlife.

Garlic Mustard (Alliaria petiolata) Mustard Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 29

White Sweetclover (Melilotus alba) Pea Family Yellow Sweetclover (M. officinalis)

• Annualorbiennial;inthefirstseasonofgrowththeyproducevegetativeshootswhichmayreach12inches.Uprightgrowthhabit.Intolerantofshade.Whiteandyellowsweetcloverareverysimilar,differingprimarilyinflowercolor.

• Plantscangrowtosixfeettall,fromataproot.Sweet-scented,withmany-branchedstems.Leavestoothed,oblongtolanceshaped,andcompoundwiththreeleaflets.Flowerssmallandwhiteoryellow,intaperingspike-shapedclustersattheendofbranches.

• Rapidlycolonizesopenwasteareas,andspreadsquicklyalongriparianareasandriverbanks.AlreadygrowingaggressivelyalongseveralmajorAlaskanrivers.

White Sweetclover (Melilotus alba) Yellow Sweetclover (M. officinalis) Pea family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 31

Bird Vetch (Vicia cracca) Pea Family

Related Species: Winter Vetch (V. villosa)

• Perennialwhichreproducesbyseedandvegetativelybyundergroundrhizomes.Multiple,branchingvine-likestemshavesmalltendrilsandalternate,pinnately-compoundleaveswith8to10leaflets.Bilaterallysymmetricalpurpleflowersarearrangedonaone-sidedspike.Floweringoccursfromspringtolatefall.Seedscontainedininch-long,brown,lance-shapedpods.

• Birdvetchaggressivelyclimbsfencing,trees,bushes,andothervegetation,monopolizingsunlight,space,andmoisture.Spreadsalongroadsides,trails,andotherdisturbedareas.

Bird Vetch (Vicia cracca) Pea Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 33

Scotchbroom (Cytisus scoparius) Pea Family

• Perennialshrubtotenfeettallfromaforkedtaproot.Stemsstronglyangled.Leavesclover-like,deciduous.Flowersnumerous,brightyellow,arisingfromtheleafbasesalongthestem,similarinappearancetogardenpeas.Fruitspealike,flattened,brownish-black.Reproducesvegetativelyandfromseed.Seedsremainviableforuptoeightyyears.

• Foundalongforestedges,clearings,meadows,andheath.

• Growsintodenseimpenetrablestandswhichpreventreforestation,createfirehazard,andeliminateforagefordeerandotherherbivores.

Scotchbroom (Cytisus scoparius) Pea Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 35

Common Toadflax, Butter & Eggs Figwort Family (Linaria vulgaris)

• Anaggressiveperennialthatcanreproducebyseedsorrhizomes,with1to25stemsperplant.Woody,smooth,erect,leafy,ofteninclumpsto2feettall.Numerouspalegreenleavesto3incheslong,alternate,narrowandpointedatbothends.Flowersborneattheendofeachsteminspike-likeclusters,yellow,withcentralbeardedorangepatch,oneinchlong,similartosnapdragonswithaspurextendingbelowthelowerlipofthecorolla.

• Commoninroadsides,wasteareas,lakeshores,beachmeadows,pastures,andedgesofforests.Apersistent,aggressiveinvader,capableofformingdensecolonies.Toxictograzinganimals.

Common Toadflax (Linaria vulgaris) Figwort Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 37

Ornamental Jewelweed, Balsam Family Himalayan Balsam (Impatiens glandulifera)

• Annualherbwiththick,many-branched,hexagonallyangledstemswhichcangrowto10feet.Stemssmooth,multi-branched,reddishincolor,butcanalsobegreenwithlargeswollennodesandglandsatthenodes.Lowerleavesoppositeupperleaveswhorledwiththreeleavestoanode.Leaveslance-shapedtolance-ovate,6incheslong,fromastoutpetiole.Leafmarginsfinely,sharplyserrated.Irregularflowersoneinchinlength,pink-purpletowhite,withfivepetals.

• Thrivesinlowlands,riparianzones,andalongbeaches.Rapidlyclogsstreamsandwetlands.Prolificseedproductionandaggressivespreadmakecontroldifficult.UnwarygardenershavecontributedtoitsspreadintoAlaska.

Ornamental Jewelweed, Balsam Family Himalayan Balsam (Impatiens glandulifera)

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 39

Brittlestem Hempnettle (Galeopsis tetrahit) Mint Family

• Annualwhichcangrowto4fttall.Flowerspurple,pink,whiteorpaleyellowwithdarkvariegatedmarkings,growinginclustersatbaseofleafstalks.Stemsbranched,bristly-haired,squareincrosssection,andswollenbeneaththeleafstalks.Leavesoppositeonstalks,egg-shapedtolance-shapedwithlargeroundedteethandpointedtips.Leavesprominentlyveinedandcoveredwithbristlyhairs.

• Formsdensestandsondisturbedsites,forestedge,riparianareas,meadows,andbeaches.Numerousseedsaresmallandeasilyspreadonshoes,tires,andrecreationalequipment.

Brittlestem Hempnettle (Galeopsis tetrahit) Mint Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 41

Reed Canarygrass (Phalaris arundinacea) Grass Family

• Tallreed-likeperennialrisingfromstoutrhizomes.Stemsarehollow,2to6feettall,withbluish-greenwaxycoating.Leafbladesflat,upto3/4inchwide,withclaspingligules.Leavesrough,sheathsopen.Panicleinflorescenceis6to18cmlongwithspikeletsoccuringinclustersonshortscabrousbranches.Seedheadsreddishtopurplishatbase,becomingstrawcolored;compactatfirstthenopeningatmaturity.

• Highlyvariablespeciespreferringmoistsites.Beginsgrowingearlyintheseason.Spreadswithinsitesbycreepingrhizomes,effectivelyexcludingallothervegetation.Foundalongroadsides,ditches,wetlands,riparianareas,beaches,andgrowingintolakes.Formsdense,persistent,monospecificmattedstands.Difficulttoimpossibletoeradicateonceestablished.

Reed Canarygrass (Phalaris arundinacea) Grass Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 43

Downy Brome, Cheatgrass Grass Family (Bromus tectorum)

• Annualorwinterannualgrassrises2to28inchesfromafibrousrootsystem.Seedsgerminateinlatefallorearlyspring,andrapidspringgrowthproducesmatureseedroughly2monthslater.Seedheadisdenseanddrooping,andseedsrangefromstraw-coloredtopurplish.Growsinsolitaryclumpsortufts,withlight-greenleaves,andmembranousligules.Leafsheathesdenselyandsoftlyhairy.Lemmashavelong,softhairsandlongawns,givingthegrassits“downy”appearance.

• Occursonrangelands,roadsides,wasteplaces,anddisturbedsites.Willinvadegrasslandsandopenforests,especiallyonsandyorgravellysoils.Ahighlyvariable,prolificseedproducer,adaptedtoabroadrangeofsiteconditions.Earlymaturation and accumulation of dead above-ground material greatlyincreasesfirehazard.Awnsinjureeyesandmouthsofgrazinglivestockandwildlife.Downy Brome (Bromus tectorum) Grass Family

U. of Missouri Cooperative Extension Service photo by Fred Fishel.

Alaska Natural Heritage Program, photo by Irina Lapina.

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 45

Foxtail Barley (Hordeum jubatum) Grass Family

• Short-livedperennialgrass,reproducingfromseedsandtillers.Grows1to2feettall,withstemsvaryingfromsmoothtodenselyhairy.Initiatesgrowthinearlyspring,andmaturesmid-tolate-summer.Seedheadisanoddingbushyspikethatrangesfrompalegreentopurplish,withmultiple,long(1to2.5inch)awns.Stemsareslenderanderect,withdarknodes,andflatblue-greenleafbladestaperingtofinepoints.Leavesaregray-greenandhaveasandpaper-liketexture.

• Foundonopenground,inmeadows,roadsides,wasteplaces,riparianareas,andotherdisturbedsites.Awnsmaycausesoresaroundtheeyes,noses,throatsandearsofdogsandgrazinganimals.

Foxtail Barley (Hordeum jubatum) Grass Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 47

Bluebur (Lappula squarrosa) Borage Family

• Anannualorwinterannualplant,profuselybranched,growingupto24inchestall.Allsurfacesofleavesandstemarecoveredwithstiffwhitehairs.Lowerleavesareoblongandstalked,whileupperleavesaresmaller,andstalkless.Smallfive-petaledflowersarepalebluewithyellowcenters,appearingattheendsofstems,amidstclustersofsmallleaves.Similarinappearancetoforget-me-not(Myosotis) flowers,butsmaller.Seeds,or“nutlets,”havetworowsofhookedprickles,whichattachtoclothingandfurfordispersal.

• Acommonweedofroadsidesanddisturbedareasacrossthecontinent.Thisspeciesisanuisancetopeopleandanimals,asitsseedsstickonshoes,clothing,andinfur.

Bluebur (Lappula squarrosa) Borage Family

United States Geological Survey, photo by Roseann Densmore.

AdensecanopyofEuropeanbirdcherryalongastreamsideinAnchor-age.Intheareapicturedhere,birdcherryhaslargelydisplacedthenativevegetation,suchaswillowandbirch,onwhichwildlifedepends.

Species to Monitor:

Siberianpeashrub(Caragana arborescens), and European bird cherry(Prunus padus),areimportantornamentalspeciesforthenurseryandlandscapeindustriesinAlaska.

Thesehardyspeciesarewell-suitedtoAlaskanclimates,andmakegoodadditionstourbanyardsandlandscapedareas.However,recentlybothspecieshavebeenobservedmovingindependentlyintonaturalareas,outsideofcultivation.

Siberianpeashrubseedlingshavebecomeestablishedinopenwoodlands,meadows,andriparianareas,andEuropeanbirdcherryisnowthedominantvegetationalongmanyofthestreamsrunningthroughAnchoragegreenbelts.Theeasyestablishmentandrapiddisplacementofnativevegetationbybothofthesespeciesiscauseforconcern.

Pleasebevigilantwherethesespeciesareplantedandcultivated,andreporttheirmovementintonaturalareastotheCooperativeExtensionServiceorappropriatelocalagency.

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Siberian Peashrub (Caragana arborescens) Pea Family

• Uprightbranchingshruborsmalltreewithyellow-greenbarkonyoungtwigs.Maturebranchesandtrunkhavegraytoolive-greenbarkandhorizontallenticels.Leavesarealternateorwhorledandcompound,with8to12ellipticleaflets,andwithoutanendleaflet.Youngleavesarelightgreen,darkeninginsummer,andyellowinfall.Stipulesarenarrowandoftenpersistasspines.Yellowtubularflowersareborneonastalkthatgrowsfromleafaxil.Fruitisborneinpods;greenandflattenedatfirst,andsharplypointed,smoothandbrownwhenmature.

• Apopularornamentalshrub,itformsadensespreadingrootsystem,andisnowmovingintonaturalareas.AknowninvaderofwoodlandsandriparianareasinCanadaandthenorthernUnitedStates.

Siberian Peashrub (Caragana arborescens) Pea Family

Forest Service • Alaska Region, September 2004 • www.fs.fed.us/r10/spf/fhp/ 53

European Bird Cherry (Prunus padus) Rose Family

• Alow-branchedtreewhichspreadsbyseedandcanreachupto35feetinheight.Producesshowywhiteflowers,borneonfive-inchlongspikes,andalargenumberofsmallblackbitterfruitsinlatesummer.Afavoriteofsomebirds,whospreadtheseedalongstreams.Purplishgraytogreenishbark.Leaveselliptictoobovate,withsharplyserratemargins.

• AfavoriteornamentalinAlaska.Generally,moosedonotbrowsethistree.ItisnowspreadingfreelyintoriparianzonesinAnchorageandFairbanks.

• Alongurbanriversandstreams,itisthedominantunderstoryseedlingandsapling,replacingnativetreesandshrubs.

European Bird Cherry (Prunus padus) Rose Family

COMMON NAME SCIENTIFIC NAME CODE FAMILY

27 GarlicMustard Alliaria petiolata ALPE4 Mustard

29 Sweetclover,whiteandyellow MEAL12 Melilotus alba, M. officinalis MEOF Pea

31 BirdVetch Vicia cracca VICRC Pea

33 Scotchbroom Cytisus scoparius CYSC4 Pea

35 CommonToadflax,Butter&Eggs Linaria vulgaris LIVU2 Figwort

37 OrnamentalJewelweed HimalayanBalsam Impatiens glandulifera IMGL Balsam

39 BrittlestemHempnettle Galeopsis tetrahit GATE2 Mint

41 ReedCanarygrass Phalaris arundinacea PHAR3 Grass

43 DownyBrome,Cheatgrass Bromus tectorum BRIN1 Grass

45 FoxtailBarley Hordeum jubatum HOJU Grass

47 Bluebur Lappula squarrosa LASQ Borage

51 SiberianPeashrub Caragana arborescens CAAR Pea

53 EuropeanBirdCherry Prunus padus PRPA Rose

USDAisanequalopportunityproviderandemployer.

Selected Invasive Plant Species of Alaska

COMMON NAME SCIENTIFIC NAME CODE FAMILY

1 CanadaThistle Cirsium arvense CIAR4 Sunflower

3 BullThistle Cirsium vulgare CIVU Sunflower

5 OxeyeDaisy Leucanthemum vulgare LEVU Sunflower

7 SpottedKnapweed Centaurea biebersteinii CEBI2 Sunflower

9 OrangeHawkweed Hieracium aurantiacum HIAU Sunflower

11 Non-NativeYellow-floweredHawkweeds Hieracium HIUM (umbellatum, pilosella, caespitosum) HIPI,HICA10 Sunflower

13 NarrowleafHawksbeard Crepis tectorum CRTE3 Sunflower

15 HairyCatsear Hypochaeris radicata HYRA3 Sunflower

17 PerennialSowthistle Sonchus arvensis SOAR2 Sunflower

19 CommonTansy Tanacetum vulgare TAVU Sunflower

21 TansyRagwort Senecio jacobaea SEJA Sunflower

23 WesternSalsify Tragopogon dubius TRDU Sunflower

25 JapaneseKnotweed Polygonum cuspidatum POCU6 Buckwheat

Orange hawkweed invading the Kodiak National Wildlife Refuge.

U.S. Fish & Wildlife Service, photo by Leslie Kerr.