Mistaken Identity, Invasive Plants and Their Native Look-alikes

68 Pages·2009·2.83 MB·English

Mistaken
Identity ?
Invasive Plants and their Native Look-alikes
an Identification Guide for the Mid-Atlantic
MatthewSarver
AmandaTreher
LennyWilson
RobertNaczi
FaithB.Kuehn
www.nrcs.usda.gov http://dda.delaware.gov www.dsu.edu www.dehort.org www.delawareinvasives.net
Publishedby:DelawareDepartmentAgriculture •November2008
Incollaborationwith:ClaudeE.PhillipsHerbariumatDelawareStateUniversity•DelawareCenterforHorticulture
Fundedby:U.S.DepartmentofAgricultureNaturalResourcesConservationService
CoverPhotos:
Front:Araliaelataleaf(Inset,l-r:Araliaelatahabit;Araliaspinosainfloresence,Araliaelatastem)
Back:Araliaspinosahabit

TABLE OF CONTENTS
About this Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction
WhatExactlyisanInvasivePlant?..................................................................................................................2
WhatImpactsdoInvasivesHave? ..................................................................................................................2
TheMid-AtlanticInvasiveFlora......................................................................................................................3
IdentificationofInvasives ..............................................................................................................................4
YouCanMakeaDifference..............................................................................................................................5
Plant Profiles
Trees
NorwayMaplevs.SugarMaple....................................................................................................................6-7
JapaneseAngelicaTreevs.Devil’sWalkingstick ........................................................................................8-9
WhiteMulberryvs.RedMulberry ............................................................................................................10-11
Tree-of-Heavenvs.StaghornandSmoothSumac....................................................................................12-13
Shrubs
AsianBushHoneysucklesvs.NativeBushHoneysuckles........................................................................14-15
BurningBushandWintercreepervs.NativeEuonymus..........................................................................16-17
MultifloraRosevs.NativeRoses..............................................................................................................18-19
Wineberryvs.NativeBlackberriesandRaspberries................................................................................20-21
Vines
JapaneseHoneysucklevs.NativeTwiningHoneysuckles ......................................................................22-23
OrientalBittersweetvs.AmericanBittersweet........................................................................................24-25
JapaneseVirgin’sBowervs.Virgin’sBower............................................................................................26-27
Porcelain-berryvs.NativeGrapes............................................................................................................28-29
Grasses
JapaneseStilt-grassvs.Whitegrass..........................................................................................................30-31
ReedCanarygrassvs.NativeReedgrasses ..............................................................................................32-33
InvasivePhragmitesvs.NativePhragmites ............................................................................................34-35
GoldenBamboovs.SwitchCane..............................................................................................................36-37
JohnsonGrassvs.IndianGrass ..............................................................................................................38-39
Herbs
GiantHogweedvs.AngelicaandCow-parsnip........................................................................................40-41
YellowFlagvs.NorthernBlueFlag..........................................................................................................42-43
LesserCelandinevs.Marsh-marigold......................................................................................................44-45
Controlling Invasives . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Species Control Recommendations . . . . . . . . . . . . . . . . . . . . 49
Glossary of Botanical Terms . . . . . . . . . . . . . . . . . . . . . . . 52
Resources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Acknowledgements. . . . . . . . . . . . . . . . . . . . . . . . . . . 58
AboutThis Guide
Purpose:
Whilesomeinvasiveplantsaredistinctiveand
easily recognized, many others are difficult to
distinguish from one or more species of our
nativeflora. Forlandowners,managers,andthe
general public, identifying confusing invasive
plants can be extremely difficult. While many
existingpublicationsincludeidentificationtips,
none present a complete side-by-side,
illustrated comparison of the key characters
neededtoconfirmidentification. Thisguidefills
a need for a regional photographic guide to a
broadselectionofinvasiveplantsthatareoften
confusedwithsimilarnativelook-alikes.
Scope:
AninvasionofPorcelain-berry(Ampelopsisbrevipedunculata). Becauseofitsclimbing
This guide covers the Mid-Atlantic region, habit,similarleafshape,andclustersofbluishfruit,thisspeciesisoftenconfusedwith
defined here as Delaware, Maryland, New ournativegrapes(Vitisspp.)
Jersey, New York, Pennsylvania, Virginia, and
theDistrictofColumbia.
Thespeciesincludedrepresentsomeofthemostsignificantinvasiveplantidentificationchallengesintheregion,aswellas
thecorrespondingnativespecieswithwhichtheyaremostlikelytobeconfused. Manyinvasiveplantspeciesarenotincluded,
either because their identification is considered relatively straightforward, or because their impacts or distributions are
somewhatlimited. Invasiveplantspeciesincludedinthispublicationarethosethat(1)aregenerallywidespreadthroughout
theMid-Atlanticregion,orarecurrentlyexpandingtheirranges,and(2)areknowntoinvadeundisturbednaturalhabitats.
Whiledetailedcontrolrecommendationsforeachplantspeciesarebeyondthescopeofthispublication,ageneraldiscussion
ofcontrolmethods,andabriefsummaryofmethodsforeachspeciesisincluded. Moredetailedcontrolprescriptionsare
readilyavailablefrommanypublishedandonlineresources,thebestofwhichareincludedintheResourcessectionofthis
guide.
RecommendedCitation:
Sarver,M.J.,A.Treher,L.Wilson,R.Naczi,andF.B.Kuehn,2008.MistakenIdentity?InvasivePlantsandtheirNativeLook-alikes:an
IdentificationGuidefortheMid-Atlantic. Dover,DE:DelawareDepartmentofAgricultureandUSDANaturalResourcesConservation
Service.
AuthorAddresses:
MatthewJ.Sarver LennyWilson FaithB.Kuehn
SarverEcologicalConsulting HorticultureandFacilityManager PlantIndustriesAdministrator
173WallaceRd.,Blairsville,PA15717 DelawareCenterforHorticulture DelawareDepartmentofAgriculture
Email:[email protected] 1810NorthDuPontSt.,Wilmington,DE19806 2320SouthDuPontHwy,Dover,DE19901
Email:[email protected] Email: [email protected]
AmandaTreher RobertNaczi
ClaudeE.PhillipsHerbarium, CuratorofNorthAmericanBotany
DelawareStateUniversity TheNewYorkBotanicalGarden
1200NorthDuPontHwy,Dover,DE19901 2900SouthernBlvd.,Bronx,NY 10458-5126
Email:[email protected] Email:[email protected]
1
Introduction
What Exactly is an Invasive Plant?
Theterm“weed”isafamiliarwordtofarmersandgardeners. former are typically species that can compete with native
Incommonusage,aweedissimplyanyplantthatisgrowing plants in undisturbed natural areas, thus damaging the
inaplacewhereitisunwanted. Inthiscontext,virtuallyany balanceofnativeplantcommunitiesandadverselyimpacting
plantspeciescouldbeconsideredaweed,dependingonthe ecosystems.
perspective of the person applying the term. However, in
regulatory and scientific terminology, a weed is typically Whilemostofourinvasiveplantspecieshavebeenimported
defined more narrowly as a plant species that has the
fromoverseas,somespeciesthatoriginatedinNorthAmerica
potential to interfere with agricultural production or cause
have sometimes been regarded as invasive. These native
damagetonaturalecosystems.
speciesoftendominatehuman-alteredhabitats,andarenot
as problematic in natural areas. We choose to limit our
Theplantsweconsiderinvasivespeciesareasubsetofthose
species usually categorized as weeds using the narrow definitionofinvasivetoincludeonlyplantsnotnativetothe
definitionoftheterm. Invasiveplantshavethepotentialto continent, and to regard native species that can dominate
beevenmoredamagingthanagriculturalweeds,becausethe certainhabitatsasaggressive,ratherthaninvasive.
Definitions
What is the Plant’s Origin? What is the Plant’s Ecology?
Native: Invasive:
AplantspeciesthatisindigenoustoNorthAmer- Analienplantspeciesthatiscapableofrapid
ica,ortoaparticularregionwithinNorthAmerica,known spreadintorelativelyundisturbednaturalcommunitiesand
tohaveoccurredtherehistorically. that,onceestablished,causesadverseecologicalimpacts
withintheinvadedcommunity.
Alien (or Non-native):
AplantspeciesthatisnotindigenoustoNorth Aggressive:
America. Thetermreflectsonlytheoriginoftheplant,and Aspeciesofanyorigin(includingnative)thathas
notitsecology. Thereforenotallalien,ornon-nativeplants thepotentialtodominateundercertainconditionswithin
areinvasive(infact,onlyasmallfractionofthemare). itspreferredhabitat.
What Impacts do Invasives Have?
Annualestimatedeconomiclossesduetoinvasivespeciesin changesinhabitatstructurethatcanreducethebreedingsuc-
general are in the hundreds of billions. These estimated cessofbirdspecies. Invasivewetlandplantscanreplacena-
lossesincludedamagetoagriculturalcrops,fundsspenton tives, thus reducing or eliminating submerged habitat
control, etc. The ecological impacts of invasive species are structureforaquaticorganisms. Someinvasivesdisplacena-
moredifficulttoquantify,butareneverthelesscriticallyim- tiveplantsthatprovidefoodforspecializedorganisms(such
portant. Invasive plants can impact native ecosystems in a asbutterflycaterpillars). Thepossibilitiesfordisruptionof
variety of ways. They may reduce native plant diversity by interactionswithinnaturalcommunitiesarenumerousand
competitionforresources,suchaslight,water,orminerals. interconnected.
They may also alter the nearby soil conditions by secreting
chemicalsthatinhibitthegerminationofseedsorthegrowth
of other plants (an effect known as allelopathy). They may Despite their negative impacts, some invasives do provide
alternutrientcyclingandsoilcharacteristicsininvadedareas foodandcoverfornativewildlife. Inareasthatarealready
bychangingtheamount,composition,orrateofdecayofleaf highlydisturbedandlackinginnativeplantdiversity,thecon-
litter. Invasiveplantsthatarecloselyrelatedtonativespecies tributionofinvasivesashabitatorfoodforsomenativeor-
may hybridize with (and ultimately genetically “swamp”) ganismscanbeimportant. Forthisreason,whenplanningan
theirnativerelatives. invasiveplantcontrolscheme,caremustbetakentoevaluate
thepotentialbenefitsthattheinvasiveiscurrentlyproviding
Alongwithachangeinplantcommunitiescomesacomplex forotherorganisms,andtoreplacethatbenefitbyrestoring
web of impacts on other organisms. Some invasives cause theareawithappropriatenativeplantspecies.
2
Introduction
The Mid-Atlantic Invasive Flora
Demographics
The Mid-Atlantic, situated at a zone of transition between southern and northern floras, and encompassing many
physiographicprovincesandsoiltypes,hostsadiversegroupofnativeplantspecies. AlonghistoryofEuropeansettlement
intheeasternpartoftheregion,followedbyextensiveurbanization,hasledtotheestablishmentofanumberofalienand
invasiveplantspecies. InDelaware,forexample,alienspeciesaccountfor43%ofthetotalflora,withabout6%oftheflora
consideredinvasive. InPennsylvaniaanestimatedonethirdofthefloraisconsideredalien,andaround2%isconsidered
invasive. Asthesefiguresindicate,whilealienspeciesarewell-representedinourregion’sflora,arelativelysmallproportion
ofaliensarelikelytobecomeinvasive. Thus,thesignificantecologicalandeconomicimpactsofinvasiveplantspeciesare
disproportionatetotheirrepresentationintheflora.
Origins and Introduction
ThevastmajorityofinvasiveplantspeciesestablishedintheMid-AtlanticarenativetoAsiaorEurasia. Sincetheclimates
ofEuropeandtemperateAsiaaresimilartothatofthenorthern UnitedStates,thesespeciesarewell-suitedforlifeinour
region. Interestingly,whilemostofourinvasivetrees,shrubsandvinesoriginatedinAsia,manyofourherbaceousinvasive
plantsoriginatedinEurope.
Many of our invasives were first introduced as ornamental plants, usually by arboreta, botanical gardens, or less often,
individuals. Woodyinvasiveplantsinparticularwereprimarilytheresultofhorticulturalintroductions.Otherinvasives,
particularly grasses and vines, were introduced and spread by agronomists as potential livestock forage (Johnson Grass,
Kudzu). Likewise,manyshrubsandvines(Honeysuckles,MultifloraRose)werewidelypromotedbystateandfederalwildlife
agenciesascoverandfoodsourcesforwildlife,thusspreadingmuchmorerapidlythantheywouldhavebynaturaldispersal
alone. A few introductions represent other miscellaneous attempts at economic stimulus (e.g. the introduction of White
Mulberryasahosttreeforsilkwormmothcaterpillars,inanattemptbytheBritishtoestablishasilkindustryinthecolonies).
The second group of invasive plant introductions is those that were truly accidental in nature. Most of these involve
herbaceous plants introduced as seed. An example cited in this guide is the introductionof Japanese Stiltgrass via plant
materialusedaspackingforporcelainshipments.
As this summary suggests, invasive species introduction has historically been a somewhat preventable occurrence. The
horticultureindustryhasgrownmoreinterestedinstoppingtheimportationandsaleofinvasiveplants,althoughmanyare
still widely available. In addition, state and federal agencies are now focused on invasive plant eradication, rather than
introduction,reversingthepasttrendofsearchingfornovelwildlifeplants,andoptingratherforalargelynativeapproach.
Increasing globalization, however, will undoubtedly lead to further spread of plant species worldwide, making an
understandingoftheirecologyandcontrolofutmostimportance.
3
Introduction
Identification of Invasives
There are adverse ecological consequences of mistakenly controlling a native plant species. While an occasional case of
mistakenidentitymayresultintheremovalofonlyasmallproportionofthepopulationofagivennativeplant,widespread
misidentification and “control” of certain native species that are already rare or declining has the potential to result in
significantlocalandpopulation-levelimpacts. Thedeclinesofsomenativeplantspeciesappeartobecausedbythespread
of closely related invasives. Examples of native species that are declining throughout their ranges include American
BittersweetandRedMulberry. Extracareshouldbetakenindistinguishingsuchnativeplantspeciesfromtheirinvasive
counterparts. Inadditiontotheimpactsondecliningnativespeciesthemselves,theremovalofanynativeplantissureto
have complex and potentially negative impacts on the community from which it was eradicated. Finally, herbicides and
laborareexpensive,andtheseresourcesshouldnotbewastedonthecontrolofamisidentifiedplantspecies.
Identification in the Field
Whenattempting to identify anunknown plant species, it is useful to carryafew basic items to help you record accurate
information. Someofthesetoolsinclude:asmallplasticmetricruler,asmallhandlensormagnifier,anotebookandpencil,
acoupleoflarge,plasticzipperbagsforcollectingplantspecimens,asmallpairofprunersforcollectingbranchesofwoody
plants,andacompactdigitalcamerawithmacrosettingforphotographingvariouspartsoftheplantandthehabitatinwhich
itwasfound. Whilefieldguidesandbotanymanualsarehelpfultohaveonhand,ifyourecorddetailednotesandsketch,
photograph,orcollectaspecimenoftheplantinquestion,youwillbepreparedtoidentifytheplantatalatertime. Notethat
itisillegaltocollectspecimenswithoutfirstobtainingtheproperpermission(permitsfromtheappropriateagencyonpublic
land,orpermissionofthelandowneronprivateland).
Aproperlycollectedspecimenincludestheentireplant,eventheroots(whichareoftenimportantforidentification),andany
flowersorfruit(ifpresent). Iftheplantislarge,suchasatreeorshrub,snipoffapieceofabranch,andtakenotesorphotos
describingthebark. Inordertoavoiddamagetopopulationsofnativeplants,donotcollectaspecimenifthereappearsto
beonlyoneorafewplantsinthearea.
Whenyoureturnhome,removeanydirtordebrisfromtheplants,andplaceeachcollectedspecimeninsideofafewsheets
of newsprint with the date and location marked on them. Take care to spread out the leaves and turn some face-up and
othersface-downsothatbothsidesarevisible. Sandwichthenewsprintbetweentwopiecesofcorrugatedcardboard(you
cancutthecardboardtothesizeofthenewsprint)andtopthecardboardwithseveralheavybooks,orplaceitinsideaplant
press. Storethespecimenindoorsinadryareaforseveraldaystoaweekortwo,dependingonthethicknessofthespecimen
and the ambient humidity. Once completely dry, the books can be removed, and the cardboard can be taped together to
protectthespecimenuntilitcanbeexaminedbyabotanist.
Whether or not you choose to collect a specimen, it is important to record the exact location of the plant. Record GPS
coordinates,ifavailable,andmarkthelocationonadetailedmap. Takenotesonallpartsoftheplant,notingcolors,presence
orabsenceofhairs,mannerofleafattachment(opposite,alternate,whorled),thepresenceorabsenceofteeth,thenumber
ofpetalsandsepalsofaflower,etc. Noteanydistinctiveodor,thecolorofsap,andotheruniquefeatures. Besuretonote
whatthesurroundinghabitatislike(woods,fields,wetlands,etc.)andwhatotherplantsaregrowingnearby(ifyouknow
them). Note that some plants can cause dermatitis when handled, so use caution and try to avoid touching sap when
examiningandcollectingunknownplants.
Acarefulsetofnotes,especiallywhencombinedwithaseriesofphotosoraspecimen,shouldhelpyoutoidentifytheplant
inquestion.
4
Introduction
How to Use This Guide
This guide is not intended as a key or a comprehensive grassflowersandfruits. Wehavesimplifiedtheidentification
manual to plants of the region. Rather, if you suspect that process, but if you are not familiar with the reproductive
the plant you are trying to identify is one of the invasive structures of grasses, it will be helpful to have your
speciescoveredhere,thespeciesaccountwillhelpyoutorule identification confirmed by someone familiar with grass
out other similar species. In order to use this guide morphology.
effectively,ifyouhavenoideaoftheidentityoftheplantin
question, you should first consult other basic references in Always be absolutely certain of your identification before
ordertonarrowthepossibilities. Keepinmindthatnoguide eradicatingasuspectedinvasiveplant. Ifyouarestillunsure,
can cover ALL of the other species that might resemble a please consult a professional botanist or invasive species
particularinvasive. Thisisespeciallytruefordifficultgroups biologist. Often, your local extension office or your local
likegrasses. NRCS office can assist you with identification of possible
invasivespecies.
Botanical terminology is complex and extensive. We have
tried to limit the number of unfamiliar terms used in this Numerousprintedandonlineresourcesareavailabletoaidin
guide, and have provided a glossary to define the terms we plant identification. Some of the best are listed in the
douse. Wheneverpossible,wedescribethecharactermore Resourcessectionattheendofthispublication.
fullyratherthanusingatechnicalterm. Oneareaofpotential
difficulty is grass identification, which uses specialized
terminology to describe the tiny structures associated with
You Can Make a Difference
Many battles in the war against invasive plants are being won by small organi-
zations, volunteer “weed warrior” groups, local land managers, and private conserva-
tion landowners. The success of your control efforts depends largely upon your
knowledgeoftheinvasivespecieswithwhichyouareworking,includingtheirnatural
history and impacts on the ecosystem. If you take the time to carefully identify an in-
vasive plant and learn about its native look-alikes, you will find that not only will you
avoididentificationmistakes,butyouwillbecomemuchmorefamiliarwiththebiology
oftheinvasiveyouaretryingtocontrol. Thisguideshouldhelpgetyoustarted,andthe
many invaluable references available in the Resources section will assist you in your
effortstorestorethehealthofaplantcommunitynearyou.
Financial and technical assistance for invasive plant control may be available
through various NRCS cost-share programs, including the Environmental Quality In-
centivesProgram(EQIP)andtheWildlifeHabitatIncentivesProgram(WHIP). Inad-
dition,manyagenciesandprivatefoundationsoffergrantsforinvasivespeciesremoval
projects. Formoreinformation,pleaseconsulttheFinancialandTechnicalAssistance
section of the Resources page at the end of this guide, or contact your local NRCS of-
fice.
5