Invasive species

Any plant that grows outside of its natural range is considered exotic. If it responds to its new environment with rapid growth, and if it can quickly establish itself over large areas of land then it is considered invasive.

How does this happen?

When humans were introduced into North America we brought plants with us from our country of origins. Plants have

been introduced for agricultural purposes, horticultural purposes, and in some cases, purely by accident. However, when

a plant species is introduced outside its natural range, it is also outside the natural range of its natural controls that can

include any herbivores, parasites and diseases. Free from these natural controls, some exotic plants experience rapid

and unrestricted growth, become invasive in their new environments, and reduce ecosystem diversity and function.

Why aren't’t all exotic plant species invasive?

The primary factors which contribute to a plant’s ability to invade include its life cycle, annual or perennial; how it

spreads, as a vine or by seed; its capacity for abundant seed production; its high seed germination rate; how long-lived

its seeds are; and how rapid it can mature to its seed-producing stage. The quicker it can reproduce itself, the quicker it

can invade and overwhelm the native plant species which previously occupied the land.

Why should we be concerned?

Invasive plant species are the second greatest threats to the natural ecosystems of the world today. Only direct habitat

destruction poses a greater threat to the future of biological diversity. Invasive species disrupt the ecology of natural

ecosystems by displacing native plant and animal species and reduce biological diversity by reducing the amount of light,

water, nutrients and space available to native species.

What Plants are Invasive in Northeastern Ohio?

 Targeted Species

1

Garlic mustard

Alliaria petiolata

2

Autumn olive

Elaeagnus umbellata

3

Japanese honeysuckle

Lonicera japonica

4

Amur honeysuckle

Lonicera maackii

5

Morrow honeysuckle

Lonicera morrowii

6

Tatarian honeysuckle

Lonicera tatarica

7

Purple loosestrife

Lythrum salicaria

8

Reed canary grass

Phalaris aurundinacea

9

Common reed grass

Phragmites australis

10

Japanese knotweed

Polygonum cuspidatum

11

European buckthorn

Rhamnus cathartica

12

Glossy buckthorn

Rhamnus frangula

13

Multiflora rose

Rosa multiflora

 

 Well-established Species

1

Quack grass

Agropyron repens

2

Tree-of-heaven

Ailanthus altissima

3

Japanese barberry

Berberis thunbergii

4

Smooth brome

Bromus inermis

5

Flowering-rush

 Butomus umbellatus

6

Asian bittersweet

Celastrus orbiculatus

7

Common thistle

Cirsium arvense

8

Poison hemlock

Conium maculatum

9

Field bindweed

Convolvulus arvensis

10

Crown-vetch

Coronilla varia

11

Queen Anne's lace

Daucus carota

12

Air-potato

Dioscorea batatas

13

Cut-leaved teasel

Dipsacus laciniatus

14

Common teasel

Dipsacus sylvestris

15

Russian olive

Elaeagnus angustifolia

16

Hairy willow-herb

Epilobium hirsutum

17

Small-flowered hairy willow-herb

Epilobium parviflorum

18

Winged euonymus

Euonymus alatus

19

Wintercreeper

Euonymus fortunei

20

Meadow fescue

Festuca pratensis

21

Day-lily

Hemerocallis fulva

22

Dame's rocket

Hesperis matronalis

23

Yellow flag

Iris pseudacorus

24

Common privet

Ligustrum vulgare

25

Moneywort

Lysimachia nummularia

26

White sweet-clover

Melilotus alba

27

Yellow sweet-clover

Melilotus officinalis

28

Eurasian watermilfoil

Myriophyllum spicatum

29

Lesser naiad

Najas minor

30

Water-cress

Nasturtium officinale

31

Curly pondweed

Potamogeton crispus

32

Lesser celandine

Ranunculus ficaria

33

Bouncing Bet

Saponaria officinalis

34

Johnson grass

Sorghum halepense

35

Narrow-leaved cattail

Typha angustifolia

36

Hybrid cattail

Typha X glauca

37

European cranberry-bush

Viburnum opulus var.opulus

38

Periwinkle

Vinca minor

 

 Watch List Species

1

Porcelain-berry

Ampelopsis brevipedunculata

2

Nodding thistle

Carduus nutans

3

Spotted knapweed

Centaurea maculosa

4

Leafy spurge

Euphorbia esula

5

Border privet

Ligustrum obtusifolium

6

Showy pink honeysuckle

Lonicera X bella

7

Nepalgrass

Microstegium vimineum

8

Chinese silvergrass

Miscanthus sinensis

9

Star-of-Bethlehem

Ornithogalum umbellatum

10

Mile-a-minute weed

Polygonum perfoliatum

11

Giant knotweed

Polygonum sachalinense

12

Kudzu

Pueraria lobata

13

Dog rose

Rosa canina

14

Black swallow-wort

Vincetoxicum nigrum

 

For more Information:

Invasive Insects and Diseases

The introduction of exotic plant species have resulted in the escape of plant pathogens that have greatly impacted our local flora, such as Dutch Elm Disease, Beech Bark Disease, Chestnut Blight and Dogwood Anthracnose. Introduced insects that have impacted Holden include European Beech Scale, Gypsy Moth and Emerald Ash Borer.

Introduced Animals

White-tail Deer were extirpated from Ohio in the late 1800s but were re-introduced to Ohio in the late 1920s. Browsing by white-tail deer has a negative impact on all Holden collections. Deer browse destroys specimens propagated or purchased for the designed landscape. Browsing severely limits ecological function of natural areas when whole age classes and layers of woody species disappear from the landscape. Holden has protected a landscape matrix of woodland and grassland that is coincidentally optimal habitat for whitetail deer. Deer exclosure studies within the natural landscape produce quantifiable data on the impact of whitetail deer on the landscape. Infrared aerial surveys document the population density of whitetail deer in and around the Holden landscape. Historical density for whitetail deer in northeastern Ohio is eight deer per square mile. Current whitetail deer density is 29 deer per square mile. Whitetail deer are one of the strongest negative pressures on Holden landscape and require management plans to reduce population density.

Earthworms

Did you know that there are no native earthworms in glaciated North America? For many of the same reasons that earthworms are useful in a vegetable garden, they are harmful within our native woodlands that evolved with earthworms. Studies conducted by the University of Minnesota show that at least seven species of earthworms are invading Minnesota’s hardwood forests and causing the loss of tree seedlings, wildflowers, and ferns. Invading earthworms eat the leaves that create the duff layer and are capable of eliminating it completely. Big trees survive, but many young seedlings perish, along with many ferns and wildflowers. In areas heavily infested by earthworms, soil erosion and leaching of nutrients may reduce the productivity of forests and ultimately degrade fish habitat. For more information on invasive earthworms visit the Minnesota Department of Natural Resources web site.