Transcript Invasive Species - Mississauga Master Gardeners

Ontario’s
Invasive Plant
Species
Durham Master Gardeners
Website: www.durhammastergardeners.ca
What is an Invasive Species?
According to the Ontario Invasive Plant Council,
an Invasive Species is defined as:
“Alien species whose introduction
or spread negatively impact native
biodiversity, the economy and/or
society, including human health.”
http://www.ontarioinvasiveplants.ca/
How Do They Get Here?
Human Pathways
Origin
Native
Habitat
Natural Pathways
Horticultural Pathway
New species
introduced every
year in horticulture
industry
 Most are harmless
garden additions, but
a small percentage
can escape into
native habitats

Impact of Invasive Plants
A leading cause of
biodiversity loss
 Alters landscapes and
threatens native species
 Costly to control spread
 May cause serious health
problems
 Spread rapidly and easily in
new areas

Invasive Trees and Shrubs
Manitoba Maple (Acer negundo)
Native tree fast growing short lived
 Up to 60 ft tall
 Prefers sunlight and adapts to all soil types
 Spreads quickly, suckers, grows well in cities

Norway Maple (Acer platanoides)





Deciduous tree, 65 – 90 ft tall
Tolerates poor conditions
Heavy seed crop with high germination
Surface roots starve other plants
Inhibits native plant growth
Alternatives






Sugar Maple
Red Maple
Burr Oak
Red Oak
Ohio Buckeye
Butternut
Black Alder (Alnus glutinosa)
Shrub or small tree, 60- 90 ft. tall
 Rapid grower: 6-7 ft. per year
 Prefers very moist, marshy ground
 Crowds out native Alders

Russian Olive (Elaeagnus angustifolia)
Reproduces by root suckers
 Similar appearance to willow
 Hardy, grows well near highways
 Tolerates road salt, varying water
and temperature conditions

European Spindle Tree (Euonomous altus)
Winged Euonymus (Euonomous europaeus)
10 – 20 ft. tall shrub or tree
 Poisonous fruit
 Replaces native species
 No natural controls

Alternatives





Speckled Alder or Green Alder
(both native to Ontario)
Pagoda Dogwood
American Witch hazel
Serviceberry
Common hoptree
Non-native Bush Honeysuckle





Shrubs 4 – 6 ft high, showy flowers
No natural controls
High seed count
Fruit provides less nutrients to birds
Releases allopathic chemicals into
the soil and forms dense stands
Amur Honeysuckle
(Lonicera maackii)
Bell’s Honeysuckle
Morrow Honeysuckle
Tartarian Honeysuckle
(Lonicera bella)
(Lonicera morrowii)
(Lonicera tatarica)
Invasive Vines
English Ivy (Hedera helix)
Perennial evergreen vine
 Grows in a wide range of conditions
 Can escape from the garden to nearby woodlots

Japanese Honeysuckle Vine (Lonicera japonica)





Climbing Vines
Grows 80 - 120 ft long
Will kill trees
No natural controls
High seed count
Periwinkle (Vinca Minor)
Creeping, flowering ground cover
 Evergreen foliage, waxy leaves
 Escapes gardens to woodlands and
forests along wetlands and streams
 Spreads rapidly

Alternatives





Native Honeysuckle
Climbing hydrangea
American Wisteria
Native Virginia Clematis
Bunchberry (Canadian dogwood)
Perennials
Goutweed (Aegopodium podagraria)
Shade tolerant
 Spreads by rhizomes
 Most common is variegated,
but often reverts to green form

Lily of the Valley (Convallaria majalis)
Forms large clumps
 Difficult to remove
 Displaces native species
 Spreads by roots and
seeds

Oxeye Daisy (Leucanthemum vulgare)
Forms dense clumps
 Spreads by seeds and creeping
rhizome
 Host to several viruses
 Often mistaken for Shasta Daisy

Alternatives





Black-eyed Susan
Lance-leaved coreopsis
Pale Purple Coneflower
Canada anemone
Canada mayflower
Invasive Weeds
European Buckthorn (Rhamnus cathartica)
Small shrub or tree 6 – 35 ft.
tall sharp thorns
 Thrives in a wide range of
conditions
 First to leaf out and last to drop
leaves
 Birds carry the seeds

Dog Strangling Vine





(Cymanchum rossicum)
Twining vine, up to 6 ft. in height, extremely fast grower
Prefers sun but will grow in shade
No control methods to stop it
Killing forests as it spreads
Threatening Monarch Butterfly
Garlic Mustard (Alliaria petiolate)





Biennial, 1 – 4 ft. tall (introduced as culinary herb)
First year basal rosettes of round, toothed leaves that
smell like garlic
Second year white flower clusters in spring
Has spread to woodlands and flood plains, inhibiting
growth of native species
Prolific seed producer, spread by wildlife
Himalayan Balsam (Impatiens glandulifera)





Annual herb, up to 2 m tall
Prefers moist or wet soils
Creates dense stands
Seed capsules explode when touched
covering as much as 5 m
Often mistaken for native Jewelweed
Native Jewelweed
Japanese Knotweed (Fallopia japonica)






Aggressive, semi-woody
perennial 6 – 25 ft high
Spreads by rhizome and seed
Can be mistaken for Bamboo
Prefers moist to wet soil, but
tolerates drier conditions
One of the world’s most invasive
species
Will grow through concrete,
asphalt, and tear siding off of
buildings
Purple Loosestrife
(Lythrum salicaria)
Wetland perennial 2.4 metres high
and 1.5 metres wide
 Underground rhizomes can produce
30 -50 stems on one root
 Plants can produce over 2.7 million
seeds each

Degrades habitat for wildlife
by crowding out native plants
 Leaf eating beetles were
imported to eat plants with
success rates of up to 90%

Reed Mannagrass (Glyceria maxima)
Common Reed (Phragmites australis)





Aggressive, perennial grasses
Up to 7m tall
Spread rapidly through rhizomes
and root fragments
Prefer full sun to partial shade
Dense, cascading flowers
Giant Hogweed (Heracleum mantegazzianum)






Perennial, up to 5.5 m high, flowers up to 1.2 m across
Seeds slow to germinate, but remain viable for 15 years
Large roots over a metre deep
Flowers once , produces 120,000 seeds per plant, then dies
The sap contains toxins that causes contact dermatitis and
severe burns when exposed to sunlight, and blindness
Do not burn as smoke is toxic
Wild Parsnip (Pastinaca sativa)
Biennial, with edible roots
 First year basal rosette with fern-like foliage
 Second year yellowish-green flower clusters up to 1.5m
tall and 20 cm across
 Sap can cause severe burns

Questions?