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Invasive Plants BC

Invasive Plants

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  Canada thistle (Cirsium arvense) is a root-creeping perennial. Considered noxious under the BC Weed Control Act, this thistle is commonly found on roadsides, cultivated fields, pastures, logged forests, riverbanks, and other disturbed areas. It is a major concern in the Peace River, Omineca and Skeena areas, and is a widespread throughout the province. Canada thistle has purple or white flowers, with stalkless, spiny, dark-green leaves, growing to 0.3-2 metres in height at maturity. Canada thistle spreads rapidly through horizontal roots that give rise to large infestation patches nearby and out-competing native plants. Canada thistle develops seeds sparingly and may produce 1,000 to 1,500 seeds per flowering shoot. Best adapted to rich, heavy loam, clay loam, and sandy loam, it grows poorly in shaded conditions, can tolerate saline, wet, or dry soils, but does not tolerate waterlogged or poorly aerated
  (Tanacetum vulgare) Common tansy (Tanacetum vulgare) is a perennial and considered regionally noxious under the BC Weed Control Act. Common tansy is currently distributed in the following areas: 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.Common tansy has yellow disc flowers that resemble buttons in a flat-topped cluster at the top of the plant. With fern-like leaves, common tansy can grow 0.4–1.5 metres in height at maturity.Spread mainly through seeds and roots, common tansy can be transported by birds, animals, and on vehicles that have been in infested areas. Seeds can remain viable for up to 25 years; therefore, stopping seed spread is a main concern. Common tansy prefers sunny areas with well-drained soil, and often infests stream
  (Heracleum mantegazzianum) Giant hogweed (Heracleum mantegazzianum), also known as “Giant Cow Parsnip,” is a perennial and currently distributed in the Lower Mainland, Fraser Valley, Gulf Islands, and central to southern Vancouver Island.Giant hogweed has numerous small white flowers clusters in an umbrella-shaped head, with stout, hollow green stems covered in purple spots. Dark green leaves are coarsely toothed in 3 large segments with stiff underside hairs, and lower leaves can exceed 2.5 metres in length. Giant hogweed can grow up to 5 metres in height at maturity.Giant hogweed is a highly competitive plant due to vigorous early-season growth, tolerance of full shade and seasonal flooding, as well as its ability to co-exist with other aggressive invasive plant species. Each plant can produce up to 100,000 winged seeds (typically 50,000) that remain viable in the soil for up to
  (Ulex europaeus) Gorse (Ulex europaeus) is a spiny, perennial evergreen shrub, considered noxious under the BC Weed Control Act, and thrives on sunny clearings with dry, infertile soil such as sandy or rocky areas, roadsides, fields and pastures, bluffs, cutblocks, and cutbanks. It is currently distributed in Vancouver Island, West Vancouver, some of the Gulf Islands, and Skidegate on the Queen Charlotte Islands. Gorse is a dense evergreen shrub with a single upright stem, spine-like leaves, and fragrant yellow, pea-like flowers. Seedpods are hairy and black. Gorse can grow 1-3 metres in height at maturity.Growing rapidly for the first 15 years, gorse can live up to 45 years. Maturing seedpods explode and disperse up to 18,000 seeds per mature plant. Gorse seeds are easily distributed by ants, animals, birds, and machinery. Since gorse grows mainly by the ocean,
  (Hieracium spp.) Hawkweeds (Hieracium spp.) are perennial plants with 14 non-native species recorded in BC, and are difficult to identify among the 8 native hawkweed species. One of the 14 non-native species, orange hawkweed (Hieracium aurantiacum) is currently the only hawkweed considered regionally noxious under the Weed Control Act. Most hawkweeds have yellow flowers. Invasive hawkweeds are found throughout most forest regions and regional districts in British Columbia. The regional districts east of the Rocky Mountains, Northern Rockies, and Peace River Regional Districts only have a few known invasive hawkweed sites and efforts to prevent further establishment and spread are actively underway. Orange hawkweed is regionally noxious in the East Kootenay, Central Kootenay, Columbia-Shuswap, Thompson-Nicola, Bulkley Nechako, and Cariboo Regional Districts. Hawkweeds have bright orange, orange-red, or yellow ray flowers with several flower heads in clusters at the
Himalayan blackberry (Rubus discolor) is mostly a biennial plant, growing 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. 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. Himalayan blackberry has petite, white or faint pink flowers 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. Canes grow up to 3 metres in height and 12 metres in length at maturity. Evergreen leaves are predominantly large, rounded or oblong, and generally grouped in fives on first-year canes and threes on second year, flowering canes. Fruits are up to 2 cm
  (Berteroa incana) Hoary alyssum (Berteroa incana) is an annual to short-lived perennial. Considered regionally noxious under the BC Weed Control Act, hoary alyssum is most common on sandy or gravelly soils and establishes on roadsides, railway embankments, and heavily grazed pastures. It is currently found in south-central and southeastern BC including the Okanagan, Cariboo, Boundary, Thompson, and Kootenay areas.Hoary alyssum has small white flowers with deeply notched petals that are supported on slender stalks. The whole plant is covered in star-shaped hairs that are rough to touch, with grey leaves that clasp closely to the stem. Oval seedpods are chambered and held close to the stem with each chamber containing 5-7 black seeds. Hoary alyssum can grow up to 0.7 metres in height at maturity.Hoary alyssum spreads rapidly through a long season of seed production. Each plant flowers
  (Cynoglossum officinale) Hound’s-tongue (Cynoglossum officinale) is a biennial to short-lived perennial, and is considered noxious under the BC Weed Control Act. Hound’s-tongue is found on dry pasture, roadsides, and logged forestland. Found primarily in the southern interior of BC, it is a major concern in the Kootenay, Okanagan, Thompson, and Cariboo areas.Mature hound’s tongue plants have a woody taproot, with rough, hairy, wide leaves and dull reddish-purple, five-petal flowers. Each flower produces four rounded-triangular seeds covered with hooked prickles. Growing 0.5-1.2 metres tall, stems leaves are short and stalkless. First year plants form a rosette with leaves hanging down to resemble the shape of a dog’s tongue.Each plant produces 2,000-4,000 barbed seeds a year that cling easily clothing, livestock and wildlife, resulting in new infestations spread over great distances. Hound’s-tongue decreases forage production on rangeland and pastures. Barbed
  (Polygonum spp.) Knotweeds (Polygonum spp.) 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). 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. 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.Knotweeds have 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

Other Invasive Organisms

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Common Carp. Text.
Didymo (Didymosphenia geminate) or “Rock Snot” is a fresh water diatom most commonly found in high elevation streams and rivers throughout northern Europe and North America. It has long been considered a ‘cold-water’ algae, but has since spread to warmer lower elevation streams and rivers. It can form massive blooms causing significant negative impact to freshwater fish, plants and invertebrates through habitat and food web alteration.   Its most distinguishing feature is a slimy brown layer or ‘ blooms’ that smothers rocks, aquatic plants or any other structures in the water.  The blooms resemble thick slimy looking mats and are distinguished from other forms of algae by its brown, beige or white color.  Didymo is never green in colour.   Although Didymo looks slimy in appearance, it is spongy and scratchy to the touch and has a texture similar to
The Eastern grey squirrel (Sciurus carolinensis) may be cute and fuzzy to on-lookers, especially in the popular tourist areas of Stanley Park in Vancouver, but it is an invasive mammal in British Columbia that is ranked by the Invasive Species Specialist Group (ISSG) as one of the Top 100 Invasive Species in the world. This small mammal has some big ecological impacts—it has depleted populations of the European red squirrel through out-competition and disease (parapoxvirus), and displaces native birds of their nesting habitat, eating the birds’ eggs and nestlings. It also competes with native mice and voles. Economically, Eastern grey squirrels cost homeowners repairs due to digging up of lawns and gardens, chewing through electrical wires, eaves and shingles, and nesting in roofs, attics, and chimneys. Fruit and nut trees and vines may not produce as well due to the
Largemouth Bass  
The New Zealand mud snail is a very tiny aquatic snail (often smaller than your baby fingernail) and is native to fresh waterbodies in New Zealand. The New Zealand mudsnail is typically light to dark brown in colour but may look black when wet. The shell of adult mud snails usually have 5 – 6 whorls that lean to the right, are less than 5 mm in size and can easily be confused with other fresh water and native snails. It is thought that the New Zealand mudsnail was transported to North America in the ballast water of transport ships originating from Europe and Asia. It was first recorded in North America in the late 1980’s in Idaho’s Snake River and is now widespread in many states including Washington, Oregon, and California. The New Zealand mudsnail can live in a
Appropriately named for its ‘fire’ like sting, the European fire ant (Myrmica rubra) will attack aggressively if disrupted. When this ant attacks, it pinches down with its mandible then swings around and stings multiple times. In a few cases it has produced severe allergic reactions including anaphylactic shock. The European fire ant is a small red to brownish red ant that can be identified by its two waist segments, our native ant only has one, and the two backward pointing spines and stinger (visible with a magnifying glass).  This invasive insect was introduced from its native Eurasia to eastern North America. It was first sighted along the eastern seaboard of the United States in the early 1900s and has since spread across several Canadian provinces including Nova Scotia, New Brunswick, Quebec, Ontario, and into British Columbia. European fire ant nests

Weed of the Week: Burdock


Articles_pg_burdock
What does tainted milk, tangled fur, intestinal hairballs, and velcro all have in common? That would be the vigorously self-seeding invasive plant known as common burdock (Arctium minus).

Common burdock grows in low to mid-elevations in British Columbia and is well known for prickly burs that cling stubbornly to clothing and animals. Its more popular qualities include medicinal and culinary uses, and observation of its hooked spines that led to the invention of Velcro in the early 1940s by Swiss inventor, George de Mestral.

First introduced to North America in the 1700s for its medicinal characteristics, common burdock was a popular trading item between English and French settlers and is one of four burdock species that was introduced into North America. Common and great burdock (Arctium lappa) are the two weedy species.

Burdock’s brownish-green, deep roots are used as a traditional medicinal herb for many ailments, including as a remedy for dry and scaly skin conditions such as psoriasis and eczema, and as a blood purifier clearing the bloodstream of some toxins. In traditional Chinese medicine, burdock is often used with other herbs for sore throat and colds.

Additionally, burdock root oil extract, also called bur oil, is popular in Europe as a scalp treatment applied to improve hair strength, shine and body, help reverse scalp conditions such as dandruff, and combat hair loss. 

Despite the practical uses for burdock, there is a down side. The infamous hook-and-loop system on burdock seeds helps them to disperse, hitching rides on passing animals and people, thereby creating new infestations over great distances. Shakespeare describes it well in Troilus and Cressida, when Pandarus says, “They are Burs, I can tell you, they’ll stick where they are thrown.”

Common burdock is a Eurasian, biennial herb that tolerates most soil conditions. Plants are identifiable by wavy, heart-shaped leaves that grow alternately on the stem, and purple, prickly flowers borne in clusters at the top. Burdock typically blooms between July and October. Seeds mature by September and are spread throughout the winter and spring. Various insects pollinate burdock, particularly honeybees, bumblebees and leaf-cutting bees.

Common burdock is considered an invasive plant in BC. Invasive plants grow and spread quickly, outcompeting native plants and causing damage to the environment, economy and our health; they are the second greatest threat to biodiversity after habitat loss.

Though a treat for pollinators, common burdock can seriously disrupt native ecosystems. Although found primarily on disturbed sites, it will spread to natural areas from nearby roadsides, rail tracks, and abandoned fields. Burdock infestations can be found in grasslands and forests, and along roadsides, ditches, stream banks, and pastures.

Reaching heights of 1 to 3 metres, its large leaves can shade out and prevent other plants from growing, having an adverse effect on crop quality. Burdock has been known to reduce the value of wool due to the seed heads entangling in it, and is responsible for tainting milk products if grazed in large quantities. Additionally, burdock plants indirectly affect the development of economically important plants by hosting powdery mildew and root rot.

Reproducing only by seed, each plant can survive up to 4 years, and seeds 2 to 10 years. An average of 100 burs are produced per plant each season, with each bur containing about 40 seeds. Some studies suggest upwards of 15,000 seeds per plant are produced during its life span.

Common burdock is considered a Noxious Weed under the BC Weed Control Act because of its ability to disperse to reduce crop quality, disperse easily, and sicken livestock. The burs can cause irritation if they cling to the eyes, throat, mouth, or the inside of the stomach of livestock. In some cases the seeds must be surgically removed.

Plants may pose a health risk for livestock, but for areas in Asia, particularly in Japan, the taproot of young burdock plants are harvested and eaten by people as a root vegetable. Burdock contains inulin, a natural dietary fiber, and has also been used traditionally to improve digestion.

Burdock may be a health remedy for some and a food choice for others, but ultimately, infestations are a burden to biodiversity in BC, and should be prevented or controlled. In order to remove this problematic plant, the large taproot systems that grow deep underground must be tilled after rigorous mowing. Most broadleaf herbicides are also useful for control. Hand-cutting below the root crown can also be effective.

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April 7, 2014, Richmond Review, by Martin van den Hemel: The European fire ant is...
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