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Giant Hogweed (Heracleum mantegazzianum)
Origin: Asia
•
Introduced as an ornamental
~5 invasions reported on Gabriola Isld.
Characteristics:
•
Perennial herb, up to 5 m in height
•
Flowers: small, white, in large flat-topped
umbrella-like clusters <0.8m in diameter
•
Leaves: large, coarsely-toothed, <2.5 m long
•
Stems: hollow, green with purple spots, hairy
•
Roots: stout taproot, fleshy fibrous roots
WARNING! Stems and stalks exude clear watery
sap that sensitizes skin to UV radiation, leading
to severe burns, blistering & painful dermatitis,
and often resulting in long-term scarring.
Giant Hogweed (Heracleum mantegazzianum)
Infests: Open, sunny, moist areas
~5 invasions reported on Gabriola Isld.
Reproduction:
Seeds: <50,000/yr, viable for <10 yrs, dispersed by
wind and animals
Management:
•
Biocontrol – none
•
Manual/mechanical:
•
Mature: remove flower heads prior to seed-set, cut
stems and sever roots ~12cm below ground
•
Immature: mow every 2 wks to exhaust the seedbank, or
cut then cover with black plastic & monitor for re-growth
WARNING! Wear waterproof protective clothes,
including gloves, long sleeves, pants and eye protection
(see WorkSafeBC protocol)
USDA APHIS PPQ Archive
King County Weed Control Board, WA
•
FRPA, WCA
Gorse (Ulex europaeus)
Origin: Europe
•
Introduced as an ornamental, for stock fodder and for
stock-proof hedgerows
Characteristics:
•
Perennial shrub, up to 3 m in height
•
Flowers: yellow, pea-like, on short
velvety stalks
•
Leaves: alternate, reduced to stiff
branched spines on mature plants
•
Stems: 5-angled
~1 invasion reported on Gabriola Isld.
FRPA, WCA
Gorse (Ulex europaeus)
Infests: Dry, open, sunny, disturbed areas
•
Reduces access, increases fire hazard, impedes forest regeneration
Reproduction:
•
Seeds: <600/m2/yr, viable for <40 yrs
Management:
•
Biocontrol – none in Canada
•
Manual/mechanical – repeatedly cut
below ground, before seed set
•
Other – goats and sheep can browse
& trample young plants
~1 invasion reported on Gabriola Isld.
Himalayan Blackberry (Rubus discolor)
Origin: Asia
•
Many invasions reported on Gabriola Isld.
Introduced for the cultivation of its fruit
Characteristics:
•
Perennial; trailing/arching canes <10m long; thorns
•
Leaves: palmately compound; oblong, toothed leaflets
•
Flowers: white to pale pink; <2.5cm in diameter
•
Fruit: dark purple to black when ripe
•
Roots: woody root ball
NOTE: Be sure not to confuse this plant with the
native Trailing Blackberry (Rubus ursinus).
Himalayan Blackberry (Rubus discolor)
Infests: Open, sunny areas with well-drained soil
Reproduction:
•
Seed: viable in the soil for several years
•
Vegetatively: rhizomes, “runners” & plant fragments
Management:
•
Biocontrol – none
•
Manual/mechanical – Pull young plants from the
ground and dig up the root ball. Cut larger
canes to the ground with loppers and dig up the
root ball. Remove the biomass from the site.
Plant native trees or shrubs to create shade.
Many invasions
reported on Gabriola Isld.
FRPA
Knotweeds (Fallopia spp. & Polygonum spp.)
Origin: Asia
Characteristics:
•
Perennial, up to 5 m in height
•
Flowers: white to green, in showy plume-like
clusters
•
Leaves: variable between species
•
Stems: hollow, bamboo-like canes
By: dankogreen www.flickr.com
FRPA
Knotweeds (Fallopia spp. & Polygonum spp.)
Japanese Knotweed (Fallopia japonica)
•
Smaller in stature
than other species
(~2 m)
•
Leaf bases flat,
not heart-shaped
•
Flower clusters
longer and more
ornamental
•
Mostly female
~2 invasions reported on Gabriola Isld.
FRPA
Knotweeds (Fallopia spp. & Polygonum spp.)
Giant Knotweed
•
Tallest species (>5 m)
•
Very large leaves with heart-shaped bases
•
Mostly male
Giant K.
Bohemian Knotweed
•
Japanese X Giant Knotweed
•
Stiffly upright flower clusters
•
Rounded leaf tip
Bohemian K.
B
Himalayan Knotweed
•
Long, tapered leaf
G
Himalayan K.
J
H
FRPA
Knotweeds (Fallopia spp. & Polygonum spp.)
Infests: Open, moist, disturbed areas, & riparian areas
•
Increases soil erosion; reduces sight lines along roads &
right-of-ways; impedes access to water for recreation
Reproduction:
•
Seeds: occasionally
•
Rhizomes (roots): spread <20m away
•
Stem fragments can sprout roots
Management: Biocontrol - none
•
Manual/mechanical – cut to the ground 2x/mth
from Apr-Aug, then monthly until 1st frost
•
When controlling it near streams or ditches,
prevent the movement of plant parts downstream
By: dankogreen www.flickr.com
FRPA, WCA*
Oxeye Daisy (Leucanthemum vulgare)
Origin: Eurasia
•
Likely introduced as an ornamental
Characteristics:
•
Perennial herb; up to 1m in height;
•
Flowering head: white petals; yellow centre;
solitary at the end of flowering stems
•
Leaves: variable
~15 invasions
reported on Gabriola Isld.
FRPA, WCA*
Oxeye Daisy (Leucanthemum vulgare)
Infests: Prefers open, sunny, disturbed areas
•
Tolerates: full sun to part-shade, moist to dry soil
•
Readily spreads into native habitats
•
Carries several crop diseases, and gives milk an
unpleasant taste
Reproduction:
•
Seed: prolific seed producer; viable for 20yrs in the
soil; can remain viable after digestive by animals
•
Rhizomes
Management:
•
Biocontrol – none
•
Manual/mechanical – pull/dig plants from soil, leaving
no fragments behind; thick, heavy layer of mulch
~15 invasions
reported on Gabriola Isld.
FRPA, WCA
Scentless Chamomile (Matricaria perforata)
Origin: Europe
•
~2 invasions
reported on Gabriola Isld.
Likely introduced as an ornamental or seed contaminant
Characteristics:
•
Annual, biennial or short-lived perennial herb;
<1 m in height
•
Flowers: 2-3 cm in diameter; look like small
oxeye daisies; several at end of each stem
•
Leaves: finely divided; fern-like; dill-like
•
Roots: extensive fibrous network
Andy’s Northern
Ontario Wildflowers
BC MAL
FRPA, WCA
Scentless Chamomile (Matricaria perforata)
Infests: Open, sunny, disturbed areas
•
~2 invasions
reported on Gabriola Isld.
Reduces yields in hay fields, pastures and cropland
Reproduction:
•
Seed: >200,000/yr; float on water; can
remain viable after passing through the
digestive tracts of animals
Andy’s Northern
Ontario Wildflowers
Management:
•
Biocontrol – 2 weevils & a gall-forming midge
•
Manual/mechanical – repeatedly pull or mow
before flowering to prevent seed set;
burn/torch
BC MAL
WCA
Perennial Sowthistle (Sonchus arvensis)
Annual Sowthistle (Sonchus oleraceus)
~5 invasions
reported on Gabriola Isld.
Origin: Europe
•
Likely introduced as a crop seed contaminant
Characteristics:
•
Perennial sowthistle: perennial forb; extensive
creeping roots; 0.4-1.5 m tall; stems branch near
the top; contain a bitter milky juice; yellow,
dandelion-like flowers <3.8 cm diameter; leaves
have spiny/prickly margins
•
Annual sowthistle: taprooted; much smaller flowers
(<2.5 cm across)
Annual Sowthistle
WCA
Perennial Sowthistle (Sonchus arvensis)
Annual Sowthistle (Sonchus oleraceus)
Infests: Open, sunny, disturbed areas, &
riparian areas
~5 invasions
reported on Gabriola Isld.
Reproduction:
•
Seed:
•
•
•
Annual Sowthistle: ~6,000/yr; viable for several yrs in soil;
dispersed by wind, water and animals
Perennial Sowthistle: <35,000/yr; short-lived seedbank;
dispersed mainly by wind
BC MFR
Rhizomes (Perennial Sowthistle only)
Management:
•
Biocontrol – none
•
Manual/mechanical – repeatedly pull, or mow (Annual
Sowthistle only), before flowering to prevent seed set
Perennial Sowthistle
Neil Fletcher
Spurge Laurel (Daphne laureola)
Origin: Europe
•
Introduced as an ornamental
Characteristics:
•
Long-lived, evergreen shrub, <1.5 m in height
•
Flowers: small, cream to light green, with
orange stamens, clustered at the base of
the leaves
•
Leaves: dark green, thick, shiny, and densely
whorled
•
Fruits: clustered, black, oval berries, each
with a single seed
Spurge Laurel (Daphne laureola)
Infests: Dense forests to open sunny areas
WARNING! Sap can cause dermal irritation and
respiratory distress.
Reproduction:
•
Seeds
Management:
•
Biocontrol – none
•
Manual/mechanical – hand-pull plants with
stems <1.5 cm in diameter; cut plants with
stems >1.5 cm below ground
WARNING! Wear protective clothing/gear when
managing Daphne and do not store biomass in
enclosed spaces (see WorkSafeBC protocol)
FRPA, WCA
Tansy Ragwort (Senecio jacobaea)
Origin: Eurasia
~10 invasions
reported on Gabriola Isld.
Characteristics:
•
Biennial to short-lived perennial, <1.2 m tall
•
Flowers: small, yellow, daisy-like, clustered
at the top of stems
•
Leaves: alternate, deeply cut/pinnate
(ragged appearance)
FRPA, WCA
Tansy Ragwort (Senecio jacobaea)
Infests: Open, sunny areas
•
Very toxic to livestock, toxins accumulate
and cause photosensitivity and liver damage
•
Toxic to humans – toxins appear in milk and
honey from infested fields/pastures
Reproduction:
•
Seeds: >150,000/yr, viable for >20 yrs,
dispersed by wind, water and animals
Management:
•
Biocontrol – 5 agents in BC: 2 beetles,
2 moths and 1 fly
•
Manual/mechanical – repeated mowing or
hand-pulling before flowering
~10 invasions
reported on Gabriola Isld.
FRPA
Yellow Flag Iris (Iris pseudacorus)
Origin: Europe and northern Africa
•
Introduced as an ornamental
Characteristics:
•
Herbaceous aquatic perennial, <1.25 m in height
•
Flowers: yellow, large, showy, solitary, on the
tops of stems
•
Leaves: mostly basal, erect, sword-like, arise
from the soil in a fan
~10 invasions
reported on Gabriola Isld.
FRPA
Yellow Flag Iris (Iris pseudacorus)
Infests: Aquatic and riparian areas
•
Forms dense monocultures, reducing aquatic
habitat and impeding water flow
•
Toxic to cattle, pigs and humans; can cause
dermal blistering or irritation, as well as
vomiting or diarrhea if ingested
Reproduction:
•
Seeds and rhizomes (roots)
Management:
•
Biocontrol – none
•
Manual/mechanical – hand-pull small invasions,
and mechanically remove larger invasions;
must remove entire root mass.
~10 invasions
reported on Gabriola Isld.
Invasive Plants
Not Yet “Found”
on Gabriola Island
Carpet Burweed (Soliva sessilis)
Seed
(3-5mm)
Origin: South America
•
First discovered on BC’s coast in 1996
Washington Noxious
Weed Control Board
Characteristics:
•
Broadleaf winter annual, <7 cm in diameter
and height, grows fall to summer
•
Leaves: slightly hairy, carrot-like
•
Flowers: tiny, greenish-yellow
Carpet Burweed (Soliva sessilis)
Seed
(3-5mm)
Infests: Open, sunny areas with short vegetation
•
Trailsides, roadsides, lawns, golf courses, RV Parks, and
rocky outcrops
Reproduction:
•
Seeds: spine-tipped, 5-10/flower, viable for <20 yrs,
spread by people, pets, tires, sports equipment, etc.
•
Seeds pierce skin, causing discomfort and infection in
people and their pets.
Management:
•
Manual/mechanical – repeatedly pluck plants before
flowering to prevent seed set & deplete seedbank
•
Fire – Tiger torch prior to seed set & re-seed/plant
•
Biocontrol – none
Washington Noxious
Weed Control Board
FRPA, WCA
Knapweeds (Centaurea spp.)
Origin: Europe
•
Likely introduced as a crop seed contaminant
Characteristics:
•
Biennial or shot-lived perennial forb, <1.8 m in height; 1st
year rosette of leaves, flowering stems in following year(s)
•
Flowers: pinkish-purple, solitary at ends of stems, thin
ragged petals, dark fringed bracts
•
Roots: stout taproot, thick lateral roots (Black K. only)
•
Leaves:
•
Spotted K. - alternate, pinnate, rosette at base of stem
•
Black K. & Meadow K. – basal leaves lance-shaped, wavy
margins, sparsely hairy, stalked; stem leaves small & un-lobed
•
Diffuse K. – alternate, pinnate, hairy
BC MAL
FRPA, WCA
Knapweeds (Centaurea spp.)
Infests: Open, sunny areas
•
Can cause skin irritation
•
Contains a possible carcinogen
Reproduction:
•
Seeds: <140,000/m2/yr, viable for >8 yrs, dispersed by
humans, animals, equipment or vehicles
•
Rhizomes: Black K. only.
Management:
•
Biocontrol – several agents in BC including beetles,
moths, flies, and a stem/leaf rust
•
Manual/mechanical – repeated mowing, cutting or
hand-pulling before seed set; mowing/cutting may
stimulate low-growing form (hand-pulling preferable).
BC MAL
FRPA, WCA
Leafy Spurge (Euphorbia esula)
Origin: Eurasia
Characteristics:
•
Long-lived, perennial forb, up to 1 m in height
•
Flowers: small, yellowish green, paired bracts, arranged in clusters
•
Leaves: alternate, lance-shaped
Infests: Open, sunny areas, often
with dry coarse soils
•
Contains a milky latex that is poisonous
to some livestock and causes skin
reactions in humans
•
Produces allelopathic compound that
inhibits the growth of other plants
FRPA, WCA
Leafy Spurge (Euphorbia esula)
Reproduction:
•
Rhizomes (roots): spread <9m deep and <4.5m laterally, with <300 buds
•
Seeds: <130,000/yr, viable for <8yrs, dispersed by animals and water
Management:
•
Biocontrol – 7 agents in BC: 5 fleabeetles and 2 moths
•
Manual/mechanical – generally
unsuccessful
•
Other – sheep-grazing has been
successful in the US
FRPA
Orange Hawkweed (Hieracium aurantiacum)
Origin: Europe
Characteristics:
•
Perennial forb, up to 1.2 m in height
•
Flowers: orange, ray-flowers with notched tips,
arranged in terminal clusters
•
Leaves: mostly basal, covered with stiff hairs
•
Stems: stiff, hairy, usually solitary
FRPA
Orange Hawkweed (Hieracium aurantiacum)
Infests: Open, sunny, disturbed areas
•
Rapidly forms dense mats due to stolons
Reproduction:
•
Seeds: hundreds/stem
•
Rhizomes
•
Stolons/runners (horizontal stems, produce new roots)
Management:
•
Biocontrol – none
•
Manual/mechanical – repeated hand-pulling ensuring
seeds and stolons are not left behind
FRPA
Purple Loosestrife (Lythrum salicaria)
Origin: Eurasia
•
Introduced as an ornamental
Characteristics:
•
Perennial forb, up to 2 m in height
•
Flowers: purple, in long terminal racemes
•
Leaves: simple, oblong, opposite or whorled
•
Annual stems from perennial woody rootstocks
Town of High River
FRPA
Purple Loosestrife (Lythrum salicaria)
Infests: Aquatic and riparian areas, and ditches
•
Forms dense monocultures, reducing plant and animal
diversity in wetlands; impedes water flow
Reproduction:
•
Seeds: <300,000/stalk/yr, viable for <20 yrs,
dispersed by water
•
Rhizomes (roots)
•
Vegetative from plant fragments
Management:
•
Biocontrol – 3 agents in BC: all beetles
•
Manual/mechanical – hand-pulling before
seed set may be effective on very small
infestations; the entire root must be removed
Town of High River
Spartina (Spartina spp.)
Origin: South America and Eastern US
•
First discovered on BC’s coast 10-20 yrs
ago
Characteristics:
•
4 species: S. densiflora, S. patens, S.
anglica, S. alterniflora
•
Perennial, marine grass
•
Leaves: variable, depending on the species
•
Inflorescence: variable, depending on the
species
People for Puget Sound
People for Puget Sound
People for Puget Sound
Spartina (Spartina spp.)
Infests: Inter-tidal mud flats and salt
marshes
Reproduction:
•
Seeds
•
Rhizomes
Management:
•
Biocontrol – none
•
Manual/mechanical – pull plants once or
twice per year, before flowering; if unable
to pull the plants, clip and bag flowering
heads to prevent see production/spread
People for Puget Sound
People for Puget Sound
People for Puget Sound
FRPA, WCA
Toadflax (Linaria spp.)
Origin: Europe
•
Likely introduced as an ornamental
Characteristics:
•
Perennial forb, up to 1.2 m in height
•
Flowers: yellow, resemble snap-dragons,
borne in loose terminal racemes
•
Leaves: alternate, ovate (Dalmatian T.) or
lance-shaped (Yellow T.)
FRPA, WCA
Toadflax (Linaria spp.)
Infests: Open, sunny, disturbed areas
•
Undesirable forage, toxic to livestock
Reproduction:
•
Seeds: <500,000/yr, viable for <10 yrs,
dispersed by wind and animals
•
Rhizomes
Management:
•
Biocontrol – 5 agents in BC: 3 beetles and
2 moths
•
Manual/mechanical – repeated hand-pulling
before seed set each year
Resources
Coastal Invasive Plant Committee (CIPC)
www.coastalinvasiveplants.com
[email protected]
Weed Hotline: 250-857-2472
•
Invasive Plant Council of B.C. (IPCBC)
www.invasiveplantcouncilbc.ca
•
E-Flora BC (Online atlas of the plants of BC
www.eflora.bc.ca
• Weeds BC:
www.weedsbc.ca
Note: This website’s Resources section contains PDF versions of the
“Guide to Weeds in BC” and “Seven Steps to Managing Your Weeds”.
Resources
•
IAPP – Invasive Alien Plant Program:
http://www.for.gov.bc.ca/hra/Plants/application.htm
• The Global Invasive Species Team (TNC):
www.tncweeds.ucdavis.edu/esadocs.html
• Garry Oak Ecosystem Recovery Team (GOERT):
www.goert.ca
• CalPhotos:
www.calphotos.berkeley.edu/flora/