Download SPOTTER`S NETWORK Invasive Plants 101

SPOTTER’S NETWORK
Invasive Plants 101 - Plant Notes
Blueweed (Echium vulgare)
Identification:
• ID KEY: Stems covered in stiff hairs with swollen reddish to black bases where
attached to stem that form noticeable flecks. Hairs are painful to the touch.
• Biennial to short-lived taprooted perennial
• Basal rosette in first year (spring)
• Growing to 0.3 to 0.8 meters tall by late June
• Flowers are initially reddish, later turning deep blue to purple with white centres
• Flowers are only on the upper sides of short, rough stems
• Rough hairy leaves become progressively smaller towards the top of the plant
Habitat: Blueweed grows in dry roadsides, disturbed habitats, rocky pastures, and
rangelands at low to mid-elevations in British Columbia.
Origin: Europe
Distribution: Blueweed is in the central and south central areas of the province, it is a
major concern in the Kootenay, Okanagan, Thompson, and Cariboo regions.
Other: Blueweed invades rangelands, pastures, roadsides and idle areas particularly on
coarse, sandy to gravely soils. Blueweed is not usually found in cultivated crops, but can
invade rangelands and pastures. Seeds can contaminate clover and other crop seeds.
Spread: Blueweed spreads via seed; it produces 500 to 2,000 seeds per plant. Most
plants grow near a parent plant, seeds stick to clothing and animals.
Canada thistle (Cirsium arvense var. horridum)
Identification:
• ID KEY: Flower heads are spineless and small compared to other thistles and
there are no spines on the stem
• This perennial thistle has purple (sometimes white) flowers, smaller than most
thistle flowers
• Spiny, dark-green, oblong leaves growing directly from the stem
• Mature plants can be 0.3-2 m and have both horizontal and vertical roots
• This is the only thistle with male and female flowers on separate plants
Habitat: Prefers rich loam soil, ample precipitation, and is somewhat shade intolerant,
but it has adapted to a wide range of environmental conditions
Origin: Europe/Asia
Distribution: Canada thistle is widespread in all areas of British Columbia, and is
considered a major concern in the Omineca and Peace River regions.
1 Other: This thistle infests crops, pastures, rangelands, roadsides, and riverbanks. Thistle
thickets can restrict recreational access to infested areas.
Spread: Plants average about 1,500 seeds per plant which do not usually remain viable
after three years. However, it spreads rapidly through horizontal roots (rhizomes) that
give rise to shoots and can form dense patches and virtual monocultures.
Common tansy (Tanacetum vulgare)
Identification:
• ID KEY: Common tansy is often confused with tansy ragwort, common tansy has
no ray flowers whereas tansy ragwort does
• Aromatic perennial growing to 0.4 to 1.5 m in height
• Upright stems are often purplish red and dotted with glands
• Deeply divided dark green leaves; almost fern-like in appearance
• Yellow "disc" flowers in cluster at top of plant; no ray flowers
Habitat: Common tansy grows at low to mid-elevations along roadsides, stream banks,
in disturbed habitats, and pastures; it grows best in full sun and in fertile, well-drained
soil.
Origin: Europe/Asia
Distribution: Common tansy is found in the following regions: Bulkley-Nechako, Central
Kootenay, Columbia-Shuswap, East Kootenay, and North Okanagan Regional Districts,
and within Greater Vancouver, Fraser Valley, southeast coast of Vancouver Island, Gulf
Islands, Sunshine Coast, and Squamish/Pemberton. It is considered a major concern in
the Kootenay, Okanagan, and Omineca regions.
Other: Undesirable forage and may be toxic to livestock, it can be toxic to humans if
large quantities are consumed
Spread: Common tansy spreads by seed and roots. Seed can be transported on
animals, clothing and vehicles. Seeds can remain viable for up to 25 years; therefore,
stopping seed spread is a main concern.
Diffuse knapweed (Centaurea diffusa)
Identification:
• ID KEY: Flower-heads with small, sharp, rigid spines Thought to be hybridizing with
spotted knapweed making identification difficult at times, but can be identified
from other knapweed spp. by the terminal spine on the floral bract, occasionally
has pink flowers
• Biennial to short-lived perennial, first year in a basal rosette, see top left of slide
• Heavily branched, taprooted
• Grows to 0.6 to 1m in height
• Divided leaves grayish-green in colour, hairy
Habitat: Diffuse knapweed occurs on dry and disturbed sites, over grazed areas, and
areas with poor soil quality.
2 Origin: Europe
Distribution: Diffuse knapweed is well established in many regions of southern BC
Other: Diffuse knapweed is highly competitive, it reduces productivity of rangeland and
quickly invades disturbed plant communities thus reducing biodiversity, and increasing
soil erosion. It emits a toxin called catechin into the soil, which can kill native plants.
Diffuse knapweed is one of 13 "knapweed" species in British Columbia.
Spotted knapweed (Centaurea biebersteinni)
Identification:
• ID KEY: Flower-head bracts have a black-tipped fringe that gives a spotted
appearance
• Biennial or short-lived perennial
• Grows to a height of 1.5 m and has a stout taproot
• Hairy, deeply-cut leaves and purple (or occasionally white) flowers on one or
more upright stems
Habitat: Spotted knapweed is widespread at low to mid-elevation grasslands and dry
open forests. It has adapted to well-drained soils and can survive in very dry climates
such as those of Ashcroft and Osoyoos, but doesn't like dense shade.
Origin: Europe
Distribution: Spotted knapweed occurs frequently in southern British Columbia east of
the Coast-Cascade Mountains and is present on Vancouver Island and the mainland. It
is a major concern in the Kootenay, Okanagan, Thompson, Cariboo, Omineca, and
Peace River regions.
Other: Spotted knapweed is a highly competitive weed that reduces or displaces
desirable forage in disturbed areas, and sometimes invades adjacent areas that are
relatively undisturbed. It forms near monocultures in some areas of British Columbia.
Spotted knapweed is allelopathic, it releases a chemical (catechin) in the soil
preventing other plants from growing. Contact with this plant can cause skin irritation.
Spread: This species is prolific, with individual plants producing up to 140,000 seeds per
square metre. Although seeds are shed in the immediate area around the parent plant,
they are often spread much more widely in hay and on vehicle undercarriages.
Field scabious (Knautia arvense)
Identification:
• ID KEY: large violet to pink, clover-like flowers at the ends of long leafless stalks
• Perennial
• Stems are upright and hairy with coarsely toothed, feather-shaped leaves
• Well developed, woody taproot
Habitat: Field scabious is found on roadsides, pastures, and fields at mid-elevations.
Origin: Europe – escaped ornamental
3 Distribution: Field scabious is present the Cariboo and Peace agricultural regions and is
most troublesome in the Kootenays, Okanagan, Thompson, and Omineca regions.
Other: It competes with forage stands and native pastures and is capable of invading
undisturbed plant communities. Once established, field scabious is difficult to eradicate.
It is sometimes planted as an ornamental and to attract butterflies.
Spread: Each plant can produce up to 2000 seeds that mostly fall near the parent plant
but seeds can also be spread by birds and human activities. The seeds remain viable in
the soil for many years.
Giant hogweed (Heracleum mantegazzianum)
Description:
• ID KEY: Perennial member of the Parsley or Carrot family, resembles our native
plant, cow parsnip, grows up to 6 m or more tall
• Stem is stout, dark reddish in colour, 5-10cm in diameter
• Leaf stalks are spotted and produce a compound leaf that can expand to 1.5 m
across, each leaflet is deeply grooved or divided
• Stems and stalks are hollow and produce coarse hairs around a blister like
pustule
• Tuberous root-stalks form long-lived buds
• Small white flowers form together to make an umbrella shaped inflorescence compound umble
• The flower head can grow to 1 m in diameter
Habitat: Giant hogweed will grow in a variety of habitats but is most frequently found
adjacent to streams, creeks, roads, in vacant lots or in rights of ways. It is frequently
found in areas that are considered moist to wet.
Origin: Asia – escaped ornamental
Distribution: In BC it is known from southern Vancouver Island, the Gulf Islands, and
Vancouver.
Other: A plant takes several years from the time it germinates until it develops a
flowering stem. After flowering it sets seed and dies. Additional crowns may form on
individual plants that continue to flower and develop seed.
Spread: Giant hogweed reproduces through seed and perennial buds. Viability of seed
can exceed more than seven years.
WARNING: The greatest concern from giant hogweed is human health. The blister like
pustules on stems and stalks exude a clear watery sap that sensitizes skin to ultraviolet
radiation. Affected areas are subject to severe burns that usually result in blistering and
painful dermatitis. Blisters often result in purplish to blackened scars. Giant hogweed's
tenacious and invasive nature allows it to readily occupy and crowd out native
vegetation. In riparian areas it forms a dense canopy, out-competing native species
and causing stream bank erosion.
4 Gorse (Ulex europaeus)
Identification:
• ID KEY: Mature plants have scale or spine-like leaves that are branched and
grooved; 1.5-2cm long
• Perennial; spiny, dense evergreen, shrub
• Shrubs grow 1-3 m tall, usually with a single, densely branched, (mostly 5 angled)
upright stem,
• Single bright yellow pea-like flowers, 1.5-2cm long, fragrant, found on hairy stalks
• Leaves are trifoliate on the young plant
Habitat: Gorse grows on dry, open, sandy or rocky clearings, coastal bluffs, logged
areas, and roadsides.
Origin: Europe
Distribution: It is most common on southern Vancouver Island near Victoria, but also
occurs on a number of Gulf Islands, in West Vancouver, and Skidegate on the Queen
Charlotte Islands.
Other: Gorse competes with native vegetation, reduces access for recreation,
increases fire hazard, and has the potential to impair forest regeneration in logged
areas. It has been found to reduce pasture growth on Vancouver Island. Gorse grows
rapidly for the first 15 years, and can live up to 45 years.
Spread: The maturing seed pods explode and disperse the seeds which ants, animals,
birds, and machinery can spread. Water is a common vehicle for dispersal in BC, since
many populations grow near the sea.
Himalayan balsam/Policeman's helmet (Impatiens glandulifera)
Identification:
• ID KEY: Flowers vary from white to pink to reddish and are shaped much like an
English policeman's helmet.
• Annual succulent herb with upright, hollow, much-branched purple-tinged stems
• Grows 0.6 - 2.0 m tall
• Leaves are opposite to whorled, oblong to egg-shaped (elliptical),stalked, and
have a serrated margin
Habitat: Himalayan balsam grows in riparian areas such as wetlands, river edges and
stream banks.
Origin: Asia – escaped ornamental
Distribution: Himalayan balsam is currently found throughout the Lower Mainland, Fraser
Valley and Central Kootenay regions of BC.
Other: Has a shallow root system and can easily be pulled. Once established, tall
Himalayan balsam competes effectively against native plants. In many places it has
been known to suffocate native vegetation. Riverside and ditch-bank infestations are
spread quickly by mowing operations.
5 Spread: Each plant produces up to 800 seeds; seed capsules "explode" at maturity
releasing seeds into rivers and streams which spread far and fast to new locations.
Seeds remain viable for up to 18 months.
Himalayan blackberry (Rubus discolor)
Description:
• ID KEY: Canes are green/red in colour and grow up to 3 m in height and 12 m in
length at maturity and have large hooked or straight prickles
• Mostly biennial
• Flowers are petite, white or faint pink with 5 petals, arranged in clusters of 5-20
• Flower stalks are prickly, with robust stems (canes) that support large, flattened
and hooked or straight prickles
• Evergreen leaves are predominantly large, rounded or oblong, serrated leaf
margin, and generally grouped in fives on first-year canes and threes on second
year, flowering canes
• Fruits are up to 2 cm in diameter, oblong to spherical, black, shiny and hairless.
They form on second year canes and ripen from mid-summer to fall
• Each berry produces numerous seeds that have a hard, impermeable coat
Habitat: Preferring rich, well-drained soil, blackberries can grow well in a variety of
barren, infertile soil, and are tolerant of periodic flooding or shade. Blackberries grow on
disturbed sites, along roadsides and rights-of-ways, in pastures, along river and stream
banks, fresh-water wetlands, riparian areas, forest edges, and wooded ravines.
Origin: Asia
Distribution: They are currently distributed on the Lower Mainland, Sunshine Coast, Fraser
Valley, Gulf Islands, central to southern Vancouver Island, Queen Charlotte Islands, the
Okanagan, and the West Kootenay areas.
Other: Himalayan blackberry out-competes low growing native vegetation through
shading and build-up of leaf litter and dead stems. It can prevent the establishment of
shade intolerant trees such as Garry Oak and ponderosa pine. Blackberries form large,
dense, impenetrable thickets that can limit movement of large animals, take over
stream channels and stream banks, and reduce sight lines along rights-of-ways. Thickets
increase flooding and erosion potential by out-competing deep-rooted native shrubs
that would otherwise provide bank stability.
Spread: Spread by root and stem fragments, and birds and omnivorous mammals, such
as foxes, bears, and coyotes consume berries and disperse seeds. Humans also
contribute to blackberry spread by purposefully planting canes. Thickets can produce
7,000-13,000 seeds per square meter, and seeds can remain viable in the soil for several
years.
6 Hoary alyssum (Berteroa incana)
Identification:
• ID KEY: It is difficult to differentiate hoary alyssum from other similar species. All
similar species can be differentiated by seed head size, number of seeds per
chamber, flower colour, or location of pods on the stem.
• Annual to short-lived perennial in the Mustard Family
• Growing erect to 0.7 m tall
• Whole plant covered with whitish star-shaped hairs
• Upper leaves are elliptic and clasp the stem
• Flowers are white and have deeply notched petals
• Oval seedpods are 5 to 8 mm long, somewhat flattened and held close to the
stem
Habitat: Hoary alyssum prefers dry or gravelly soils and direct sunlight. It is generally
found at low to mid elevations in disturbed plant communities, roadside ditches,
embankments, and heavily grazed pastures.
Origin: Europe
Distribution: Hoary alyssum is currently found in south-central and southeastern BC
including the Okanagan, Cariboo, Boundary, Thompson, and Kootenay areas.
Other: Hoary alyssum can invade dry land, irrigated alfalfa fields, and rangelands and
tends to increase in forage crops following periods of drought or winterkill; infestations
can reduce hay quality and value. It can displace weak plant communities; however,
hoary alyssum’s potential to invade healthy, natural plant communities is unknown.
Spread: Seed is dispersed as a contaminant in hay and spread by vehicles, equipment,
footwear, wildlife, and birds.
Hound’s-tongue (Cynoglossum officinale)
Identification:
• Biennial, or short-lived perennial
• In its first year, hound's-tongue forms a rosette with leaves shaped like a dog's
tongue.
• Mature plants grow from 0.3 to 1.2 m tall and have rough, hairy, wide leaves
• Distinct reddish-purple, five-petal flowers.
• Each flower produces four rounded-triangular nutlets covered in hooked prickles.
• Hound's-tongue has a woody taproot
Habitat: In British Columbia, hound's-tongue grows from grasslands to mid-elevation
forests. It is found on dry sites on pastures, roadsides, and logged-over forestland,
primarily in the southern Interior.
Origin: Asia, Africa, Europe
Distribution: It is a major concern in the Kootenay, Okanagan, Thompson, and Cariboo
areas.
7 Other: Hound's-tongue decreases forage on rangeland and pastures. The plant causes
liver damage in grazing animals usually through infested hay as standing plants are
seldom grazed. The barbed seeds easily cling to the hair, wool, and fur of animals,
resulting in reduced sale value, stress on animals, and increased veterinary costs.
Although medicinal properties are purported, it is not recommended for human
consumption.
Spread: Each year a mature plant can produce up to 2,000-4,000 velcro-like seeds that
are spread great distances by humans, livestock, and wildlife.
Knotweeds (Polygonum spp.)
Description: Knotweeds are invasive perennials, with four species found in British
Columbia: Japanese knotweed (Fallopia japonica); Bohemian knotweed (Fallopia x
bohemica); Giant knotweed (Fallopia sachalenensis); and Himalayan knotweed
(Polygonum polystachyum).
• ID KEY: A distinguishing feature of Japanese knotweed is the zigzag pattern in
which leaves are arranged along the plant’s arching stems.
• Small white-green flowers that grow in showy, plume-like, branched clusters
along the stem and leaf joints
• Hollow stems stand upright and are bamboo-like with reddish-brown speckles
and thin, papery sheaths
• Leaves are heart or triangular-shaped on all species except Himalayan, which
are elongated and tapered
• Stems grow 1-5 m in height at maturity, with leaves 8-10 cm wide and 15 cm long
• Giant knotweed leaves are generally twice the size of the other 3 species.
Habitat: Knotweeds thrive in roadside ditches, low-lying areas, irrigation canals, and
other water drainage systems. They are also found in riparian areas, along stream
banks, and in other areas with high soil moisture and areas that are freshly disturbed.
Origin: Asia
Distribution: Knotweeds occur in the southwest coastal region, the Shuswap, Kitimat,
Stikine, Skeena, Columbia, Okanagan, and Kootenay areas, as well as the Queen
Charlotte Islands. Additional plants may exist in many gardens in communities across
BC.
Other: Plants emerge in early spring and produce large leaves that can shade out other
plant species. Infestations can dominate stream banks and reduce sight lines along
roads, fences, and rights-of-way. Knotweeds threaten biodiversity and disrupt the food
chain by reducing available habitat and increasing soil erosion potential. Knotweeds
can reduce or eliminate access to water bodies for recreation activities including
fishing, swimming, boating, canoeing, and kayaking.
Spread: Knotweeds spread rapidly through root systems that may extend from a parent
plant up to 20 m laterally and up to a depth of 3 m. Knotweeds are dispersed by
human activities or by water to downstream areas, and are of particular concern in
riparian areas and areas prone to seasonal high water or flooding. Stream banks are at
particular risk as exposed knotweed roots break off and float downstream to form new
infestations.
8 Leafy Spurge (Euphorbia esula)
Identification:
• ID KEY: Inconspicuous greenish yellow flowers
• Perennial with creeping root system
• Grows to 0.7m tall
• Leaves spirally arranged up the stalk
Habitat: Leafy spurge grows in areas of full sunlight and dry soil but can tolerate a
variety of habitats, such as roadsides. It occurs in agricultural areas, natural forests,
range/grasslands, rural/disturbed, scrub/shrublands, urban areas.
Origin: Europe/Asia
Distribution: There are solated infestations of leafy spurge throughout southern and
central BC.
Other: Ranked as one of the 100 most invasive species in the world – World
Conservation Union. The stems contain white milky latex, an irritant to skin and grazing
animals. An infestation of leafy spurge eliminates forage-worthy grasses while providing
no nutritional value.
Spread: Leafy spurge develops an extensive root system that can reach 4.5 m below
the soil surface and up to 10 m laterally. It out-competes native vegetation by
consuming available water and nutrients, sprouting new plants out of the existing root
system, and by shading sunlight and excreting toxins that inhibit growth of surrounding
plants. By midsummer, leafy spurge produces high yields of pollen and seed, up to 3,400
pounds of seed per acre.
Marsh plume thistle (Cirsium palustre)
Identification:
• ID KEY: Slender stems are strongly spiny-winged and are usually unbranched
except the upper portion which terminates in clusters of purple flower heads
• Biennial growing erect to about 1.5 m
• Bracts at the base of the flowers are sticky and tipped with a long spine
• Deep segmented, spine-tipped leaves are somewhat hairy on the underside and
have prominent woody veins
• Seeds are straw-coloured, 2.5 - 3.5mm long, with a 9 - 10mm long tawny pappus
• Fiberous root structure
Habitat: Marsh plume thistle grows in moist woodlands, riparian areas, roadsides and
pastures on both disturbed and undisturbed sites.
Origin: Europe
Distribution: Marsh plume thistle is actively contained and monitored at sites in Coastal
BC, near Revelstoke, and Vernon. It is a noxious weed in the Bulkley-Nechako and
Fraser-Ft. George Regional Districts and has been increasing recently in east-central
B.C. The majority of sites are located in the central interior.
9 Other: Marsh plume thistle plants replace native vegetation in open, undisturbed,
natural areas including wet meadows, fields, and riparian areas; thereby reducing
native species and threatening natural diversity. Additionally, they form dense clumps in
cut blocks, competing for moisture and nutrients with tree seedlings planted for
reforestation. Tall stems can lead to snow press, permanently damaging tree seedlings.
Spread: Reproduction by seed dispersed by wind and water as well as ingestion and
deposit by birds.
Orange hawkweed (Hieracium aurantiacum)
Identification:
• ID KEY: Flowering stalks are covered in stiff black hairs
• Fibrous rooted perennial with above ground runners
• Vibrant orange flowers (it is the only hawkweed species with orange flowers)
• Grows 30 to 60 cm tall
• Leaves mostly basal
• Flower stalks are leafless
Habitat: grows at low- to mid-elevations, usually in open areas such as pastures,
meadows, clearings, roadsides, and disturbed sites.
Origin: Europe
Distribution: Orange hawkweed is scattered and locally abundant in Central and
Southern BC and has isolated infestations on Vancouver Island. It is regarded as a major
concern in the Kootenay, Okanagan, Thompson, Cariboo, Omineca, and Peace
agricultural regions.
Other: Orange hawkweed forms dense mats of rosettes that reduce natural forage and
threaten natural diversity. Seeds will mature after plant is cut or pulled so dispose of
plants in the garbage. There are 14 species of this plant in BC (both native and
introduced).
Spread: Seeds are primarily spread by recreationalists.
Oxeye daisy (Leucanthemum vulgare)
Description:
• ID KEY: Oxeye daisy is often confused with the ornamental Shasta daisy, which
has larger yellow disk (2-3 cm) and white ray flowers (2-3 cm).
• Short-lived perennial
• Daisy-like flowers at the end of course, slender stems, with lower spoon-shaped
leaves
• Central yellow disks grow 1-2 cm wide and white ray flowers 1-2 cm long
• Can grow up to 1 m in height at maturity
Habitat: Occurs at low- to mid-elevations in grasslands and dry to moist forests. Due to
its unpleasant taste, most grazers avoid this plant, leaving it to spread easily within
grazed grasslands, pastures, and rangelands.
10 Distribution: Oxeye daisy is present in the Kootenays, Lower Mainland, and Vancouver
Island and is of major concern in the Cariboo, Okanagan, Peace River, Thompson, and
Omineca regions.
Other: Infestations decrease forage for wildlife, decrease local plant biodiversity, and
may compromise vegetative ground cover due to its growth form that results in
exposed soil.
Spread: Oxeye daisy reproduces by seed and underground stems. A single plant
produces 26,000 seeds and dispersal from parent plants lead to nearby infestations.
Purple loosestrife (Lythrum salicaria)
Identification:
• ID KEY: It has stiff, four-sided stems ending in spikes of showy purple flowers
• Perennial or woody half-shrub growing 1-3m tall
• Woody taproot with fibrous branching root system
• Short, narrow leaves that are stalkless
• Plants become taller and bushier over the years with a maturing rootstock
• Sometimes confused with fireweed (Epilobium angustifolium)
Habitat: Purple loosestrife grows in wetlands, stream banks, ditches, irrigation canals,
marshes, stream and lake shorelines and shallow ponds at low to mid elevation in BC.
Origin: Europe – escaped ornamental
Distribution: Purple loosestrife occurs in the Fraser Valley and in isolated infestations on
Vancouver Island, Okanagan, Cariboo and East and West Kootenay regions.
Other: It can form dense stands that reduce plant and animal diversity in wetland
ecosystems.
Spread: Purple loosestrife reproduces by seed (one plant can produce over 300,000
seeds), which are mainly distributed by water; however, they can also be dispersed by
animals and humans.
Rush skeletonweed (Chondrilla juncea)
Identification:
• ID KEY: Stems are covered with stiff hairs that are downward pointing
• Taprooted perennial growing to 1.3 m in height
• Branched wiry stems covered with stiff, reddish-brown downward pointing hairs
at the base
• Stems have a milky juice
• Very small leaves give plant a "skeleton-like” appearance
• small yellow flowers
• Early growth is a rosette of dandelion-like leaves that wither once the plant
flowers
Habitat: In British Columbia, rush skeletonweed occupies rangelands, roadsides, and
disturbed habitats at mid-elevations in the dry grassland zone.
11 Origin: Europe/Asia/North Africa
Distribution: Infestations of rush skeletonweed occur in the Vernon area, Crescent
Valley, Kimberley, Windermere, and Creston. It is a major concern in the Kootenay and
Okanagan regions.
Other: Infestations of rush skeletonweed can reduce livestock and wildlife forage and
the latex in the stems causes serious problems with harvest machinery.
Spread: New plants arise from lateral root buds in upper 0.6 m of soil. A single plant may
produce as many as 20,000 parachute-like seeds which are dispersed by wind, water,
animals, and humans.
Scentless chamomile (Matricaria maritime)
Description:
• ID KEY: Flowers are odourless when crushed, with semi-erect stems that are
smooth and branched with fern-like leaves
• Annual to short-lived perennial
• Single, white, daisy-like flowers with yellow centers at the ends of each branched
stem.
• Fruits are dark brown, rectangular, with 3 prominent, wing-like ribs on one side
and a pale brown broad central area on the other side
• Mature plants reach 0.15-1 m in height
• Often confused with stinking mayweed (Anthemis cotula), oxeye daisy
(Chrysanthemum leucanthemum) and pineappleweed (Matricaria
matricariodes). Stinking mayweed has a very offensive odour when crushed as
well as stem hairs below the flower heads. Oxeye daisy has flowers to 5 cm
across, rhizomatous roots and entire, notched leaves. Pineappleweed grows to
16 cm high, has no white ray flowers and has a distinct pineapple odour when
crushed.
Habitat: Scentless chamomile grows in low to mid-elevation sites, along roadsides,
drainage ditches, fence lines, dry shorelines, hay fields, pastures, and other disturbed
areas.
Origin: Northern Europe
Distribution: Scentless chamomile is currently found in all agricultural regions of BC,
scentless chamomile is a major concern in the Kootenay, Okanagan, Peace River, and
Thompson areas.
Other: This plant can infest perennial forage crops and prefers areas with high soil
moisture; therefore it is commonly found near ponds, streams, and other areas prone to
seasonal flooding. Scentless chamomile is not grazed by livestock, dense stands of
scentless chamomile can reduce crop yields in hay fields, pastures, grain fields, and
other cultivated crops.
Spread: Reproduces rapidly by seed only, with a single plant producing up to 1 million
seeds that are mature as soon as the flower forms. Seeds remain viable for up to 15
years in the soil and are readily dispersed by wind or water, on equipment and vehicles,
or as a contaminant in soil, fill material, crop seed, and animal feed. Seeds can float on
water for up to 12 hours and new infestations are often found around watercourses.
12 Scotch broom (Cytisus scoparius)
Identification:
• ID KEY: Can be confused with Spanish broom, Spanish broom flowers grow at the
tips of stems (crowning the plant), whereas Scotch Broom flowers grow along
stems
• Upright, taprooted evergreen shrub in the Legume Family
• Growing from 1 to 3 m in height
• Stems are ridged, woody, green to brownish-green and prominently 5-angled
• Upper leaves are simple and unstalked, lower leaves are stalked and comprised
of 3 oval leaflets
• Pea-like flowers are bright yellow (sometimes with red markings in the middle)
• Seedpods are flat, brown to black in colour with fine hairs on the margins
Habitat: Scotch broom invades exposed, well-drained mineral soil, and is shadeintolerant.
Origin: Europe - escaped ornamental
Distribution: Scotch broom is currently distributed on the Pacific and Atlantic coasts of
North America. It is common west of the Coast-Cascade Mountains in southwest BC
and is concentrated at the southern end of Vancouver Island. It has also been reported
on the Queen Charlotte Islands and in parts of the Kootenays and North Okanagan–
Shuswap areas.
Other: Due to its affinity for light-dominated, disturbed areas, any disturbance activity,
such as road or home construction near infested areas, can enhance spread. Scotch
Broom invades rangelands, replacing forage plants, and is a serious competitor to
conifer seedlings; Douglas fir plantation failures in Oregon and Washington have been
credited to infestations of this plant. High density infestations can:
1) Increase wildfire fuel loads, thereby escalating wildfire intensity; and
2) Obstruct site lines on roads, resulting in increased maintenance costs for removal.
Dense thickets may be impacting Garry oak woodlands in southwestern BC and limit
movement of large animals. Photosynthetic stems enable year-round growth, leading
to displacement of native plant species.Spread: Scotch broom spreads by seed and
lateral bud growth, and mature plants can produce up to 3500 pods, each containing
5-12 seeds. As seedpods dry they split and spiral, expelling the contained seeds up to 5
metres. The plant can also spread to new disturbed areas through seed transport by
vehicles and machinery.
13 Sulphur cinquefoil (Potentilla recta)
Description:
• ID KEY: It has distinctive hairy leaves divided into five to seven separate, toothed
leaflets growing on one or several stems
• Perennial member of the Rose family
• Flowers have five, sulphur-coloured, heart-shaped petals
• Mature plants grow 0.3 to 0.8 m in height
• Sulphur cinquefoil is most often confused with graceful cinquefoil, a native
species which has wooly white hairs on the underside of leaves, more basal
leaves, bright yellow flowers, and is shorter in stature
Habitat: Adapted to a wide range of soils and climates, but currently is mostly restricted
to the grasslands and dry forest zones in BC.
Origin: Europe/Asia
Distribution: It is common in southern British Columbia, and considered a major concern
in the Kootenay, Okanagan, and Thompson agricultural areas.
Other: Sulphur cinquefoil is unpalatable to grazing animals and very competitive with
native plants, resulting in reduced forage for livestock and wildlife.
Spread: Seeds are dispersed by birds, animals, and livestock, either through digestion or
by being picked up on hooves or in hair. Plants also spread through roots.
Tansy ragwort (Senecio jacobaea)
Description:
• ID KEY: Tansy ragwort is similar to several native species: (i) dryland ragwort
(Seneca eremophilus) has leaf tips that are pointed rather than rounded; (ii)
other native plants in the genus Senecio (e.g.woolly groundsel) are typically
smaller in size, do not have a unique dissected leaf structure
• Biennial or short-lived perennial
• A bushy plant growing 0.3 to 1.2 m tall
• Many deeply-cut leaves, give it a ragged appearance
• Flowers are bright yellow, daisy-like, and grouped in flat-topped clusters
• Black-tipped flower-head bracts are arranged in a single row
Habitat: Disturbed sites in pastures, hay fields, roadsides, and clear cuts
Origin: Europe/Asia
Distribution: Tansy ragwort is currently found in the central Fraser Valley, central to
southern Vancouver Island, the Gulf Islands, and the east side of the Okanagan Valley
between Kelowna and Penticton. It is a major concern in the Lower Mainland and
southern Vancouver Island.
Other: Tansy ragwort reduces forage production of pastures by up to 50%. It contains
alkaloids that can poison livestock, although the plant is often avoided. Trace amounts
of the alkaloids found in milk and honey produced raise concerns for human
consumption.
14 Spread: A single plant can produce 150,000 seeds which can remain viable for over 15
years. Seeds are dispersed by wind, water, and animals.
Yellow flag-iris (Iris pseudacorus)
Identification:
• ID KEY: Yellow flag-iris has showy yellow flowers with 3 sepals that curve
backward and 3 petals pointing upwards
• Perennial
• Leaves fold and clasp the stem at the base in a fan-like fashion, they stand erect
or bent at the top, with long sword-like leaves toward the outside of the plant
• At maturity, plants can reach 1.5 m in height
Habitat: Found in wet areas at low- to mid-elevations, growing in ditches, irrigation
canals, marshes, stream and lake shorelines and shallow ponds.
Origin: Europe/Asia/Africa – escaped ornamental
Distribution: Currently yellow flag-iris is distributed in BC’s southern interior, and has
quickly spread throughout the Okanagan valley, lower Similkameen valley, Christina
Lake and other isolated sites in the West Kootenays.
Other: Dense stands of yellow flag-iris exclude native wetland species, threatening plant
and animal diversity. Yellow flag-iris can sicken livestock if ingested, though it is
generally avoided by grazing animals. Contact with the resins can cause skin irritation in
humans.
Spread: Yellow flag-iris reproduces quickly through seed dispersal and horizontal root
systems, creating thickets in the water like cattails. Up to several hundred flowering
plants may be connected rhizomatously under the water, and fragments can form new
plants when they break off and drift downstream. Yellow flag-iris is widely sold in
nurseries and on the Internet for wet areas and well-mulched soil. While seeds disperse
in the wind and water, popularity of the plant in the market exacerbate efforts to
contain new infestations.
15