Science

Invasive Species

When plants are introduced to a new location, either intentionally or accidentally, they can spread prolifically, out-compete native species for resources, and eventually even dominate the landscape. Biologists are studying the mechanisms underlying a taxon’s ability to become invasive, but it can be difficult to predict whether or not a species will become invasive in a new habitat. With an increased awareness about the environmental and economic threats posed by invasive species, the Chicago Botanic Garden has expanded and strengthened its invasive plant policy.  We also partner with other gardens to be part of an invasive plant sentinel network, sharing information about plant species we see spreading.

Chicago Botanic Garden Status:

RRemove as soon as possible, including all cultivars, and/or do not add to collection in future
PPhase out (species that pose a lesser invasive risk, form significant structural features in landscape, and will be time-consuming to replace will be phased out over a five- to ten-year period)
EEvaluate species and cultivars, then remove invasive taxa
WWatch and monitor for signs of invasiveness

 

Scientific Name
Common Name
PlanRemoval complete?
Acer ginnala
Amur maple
PUnderway
Acer platanoides
Norway maple
R2015
Aegopodium podagraria
Goutweed
R2005
Agropyron repens
Quack grass
R*
Ailanthus altissima
Tree-of-heaven
R 
Alliaria petiolata
Garlic mustard
R*
Alnus glutinosa
European black alder
P2024
Alternanthera philoxeroides
Alligator weed
R 
Ampelopsis brevipedunculata
Porcelainberry vine
R2003
Anthriscus sylvestris
Wild chervil
R 
Arctium minus
Lesser burdock
R*
Artemisia absinthium
Wormwood
R 
Artemisia vulgaris
Mugwort
R 
Azolla spp.
Water fern
R 
Berberis thunbergii
Japanese barberry
R2017
Berberis koreana
Korean barberry
R2019
Berberis koreana x B. thunbergii (incl. 'Tara' cv.)
Hybrid barberry
R2019
Berberis vulgaris
European barberry
R 
Bromus inermis
Smooth brome
R 
Butomus umbellatus
Flowering rush
R 
Cabomba caroliniana
Fanwort
R*
Calamagrostis brachytricha
Reed grass
RUnderway
Carduus nutans
Nodding plumeless thistle
R*
Carex divulsaR 
Celastrus orbiculatus
Oriental bittersweet
R2003
Centaurea maculosa
Spotted knapweed
R 
Cirsium arvense
Canada thistle
R*
Cirsium palustre
Marsh plume thistle
R*
Cirsium vulgare
Bull thistle
R*
Conium maculatum
Poison hemlock
R*
Coronilla varia
Crown vetch
R2005
Cotoneaster multiflorus
Many-flowered cotoneaster
P 
Daucus carota
Queen Anne's lace
R*
Dioscorea batatas
Chinese yam
R2005
Dipsacus laciniatus
Cutleaf teasel
R*
Dipsacus sylvestris
Teasel
R*
Duchesnia indica
Wild strawberry
R2004
Echinops sphaerocephalus
Globe thistle
R 
Egeria densa
Brazilian elodea
R 
Eichornia crassipes
Water hyacinth
R 
Elaeagnus umbellatus
Autumn olive
R 
Epilobium hirsutum
Hairy fireweed
R 
Euonymus alatus
Winged euonymus
R 
Euonymus europeaus
European spindletree
R2005
Euonymus fortunei
Wintercreeper
RUnderway
Euphorbia cyparissias
Cypress spurge
R 
Euphorbia esula
Leafy spurge
R 
Festuca elatior (=F. arundinacea)
Tall fescue
R*
Festuca pratense
Meadow fescue
R 
Glechoma hederacea
Ground ivy
R*
Hemerocallis fulva (locally invasive)
Tawny daylily
R (wild type only) 
Heracleum mantegazzianum
Giant hogweed
R 
Hesperis matronalis
Dame's rocket
R2005
Hippophae rhamnoides
Common sea buckthorn
R*
Hydrilla verticillata
Hydrilla, water thyme
R*
Hydrocharis morsus-ranae
European frog-bit
R 
Hypericum perforatum
Common St. Johnswort
R2004
Inula helenium
Horse-heal
 
R 
Ipomoea aquatica
Water spinach
R 
Iris pseudacorus
Yellow flag iris
R2005
Lapsana communis
Nipplewort
R 
Lespedeza cuneata
Chinese bush clover
R 
Leymus arenarius
Blue lyme grass
R 
Ligustrum obtusifolium
Border privet
P 
Ligustrum vulgare
Common privet
P 
Linaria vulgaris
Butter-and-eggs
R2005
Lonicera x bella
Bell's honeysuckle
R 
Lonicera japonica
Japanese honeysuckle
R2003
Lonicera maackii
Amur honeysuckle
R 
Lonicera morrowii
Morrow's honeysuckle
R 
Lonicera tatarica
Tatarian honeysuckle
R*
Lotus corniculatus
Bird's-foot trefoil
R*
Lysimachia nummularia
Moneywort
R2003
Lysimachia verticillata
Whorled loosestrife
R 
Lythrum salicaria
Purple loosestrife
R*
Malus spp. (crabapples)
Crabapple
E, I 
Melilotus alba
White sweet-clover
R 
Melilotus officinalis
Yellow sweet- clover
R 
Microstegium vimineum
Japanese stilt grass
R 
Miscanthus sacchariflorus 
Amur silver grass
R 
Miscanthus sinensis 
Chinese silver grass, Autumn Red Miscanthus, Flame Grass, Eulalia, Maiden Grass, Zebra Grass 
R (exempted cultivars are M.s. ‘Silberpfeil,’ ‘Hinjo’ and Miscanthus x giganteus)2016
Morus alba
Mulberry
P 
Myriophyllum aquaticum
Parrot feather
R*
Myriophyllum spicatum
Eurasian watermilfoil
R*
Najus minor
Toothed water weed
R*
Nasturtium officinale
Watercress
R 
Nymphoides peltata
Yellow floatingheart
R 
Pastinaca sativa
Wild parsnip
R 
Pennisetum alopecuroides
Chinese fountain grass
RUnderway
Perilla frutescens
Beefsteak plant
R 
Phalaris arundinacea
Reed canary grass
R2004
Phellodendron amurense (excluding male cultivars)
Amur corktree
R 
Phellodendron japonica (excluding male cultivars)
Japanese corktree
R 
Phragmites australis
Common reed
R 
Pistia stratiotes
Water lettuce
R 
Poa compressa
Canada bluegrass
I 
Poa pratensis
Kentucky bluegrass
I 
Polygonum cuspidatum = P. japonicum
Japanese knotweed
R 
Polygonum perfoliatum
Asiatic tearthumb
 
R 
Polygonum sachalinense
Giant knotweed
R 
Populus alba
White poplar
P 
Portulaca oleracea
Purslane
R 
Potamogeton crispus
Curlyleaf pondweed
R*
Potentilla argentea
Silver cinquefoil
R 
Prunus mahaleb
Mahaleb cherry
P 
Pueraria montana =P. lobata
Kudzu vine
R*
Pyrus calleryana
Callery pear
R2019
Ranunculus ficaria
Lesser celendine
R 
Rhamnus cathartica
Common buckthorn
R*
Rhamnus frangula
Glossy buckthorn
R2005
Robinia pseudoacacia (native to N. Am.; aggressive in our region)
Black locust
R wild type; E cultivars2004
Rorippa sylvestris
Creeping yellow-cress
R 
Rosa caninaR 
Rosa multiflora
Japanese rose
R (check rootstocks)*
Rumex acetosella
Garden sorrel
R*
Salvinia molesta and S.minima 
Water fern
R*
Saponaria officinalis
Bouncing bet
R2005
Setaria faberi
Japanese bristlegrass
R 
Silene latifolia ssp. alba (Lychnis alba)
White campion
 
R 
Sonchus arvensis
Field sow thistle
R*
Sorghum halapense
Johnson grass
R 
Stachys balansae
No common name
R 
Symphytum asperum
Prickly comfrey
 
R 
Thalictrum buschianum
No common name
R 
Trapa natans
European water chestnut
R*
Typha angustifolia
Narrow leaf cattail
R 
Ulmus pumila
Siberian elm
R 
Valeriana officinalis
Common valerian
R2005
Verbascum thapsus
Flannel mullein
R*
Veronica gentianoides
Gentian speedwell
R 
Viburnum opulus
European cranberrybush viburnum
R 
Vinca minor
Common periwinkle
E, I 
Vincetoxicum nigrum
Black swallowwort
R*
Vincetoxicum rossicum
Swallowwort
R*

Watch List

These taxa are not currently posing a serious invasive risk in the Chicago area, but may do so in the future, particularly as the climate changes. Plan: W= watch and monitor for signs of invasiveness.  Addition of Watch List taxa to the collection should be avoided.

Scientific Name
Common Name
Plan
Akebia quinataW
Buddleja davidiiW
Elaeagnus angustifoliaW
Gypsophila paniculataW
Houttuynia cordataW
Quercus acutissimaW
Ranunculus acrisW
Ranunculus linguaW
Scilla sibericaW
Spiraea japonicaW
Syringa reticulataW
Tamarix ramosissima and other Tamarix spp.W
Verbina bonariensisW and deadhead
Wisteria sinensisW