Invasive species displace native flora and fauna and pose threats to our local environment, economy, and human health. The invasive plant species below are some of the most threatening or prevalent on Bowen Island.
Burdock (Arctium minus)
Burdock has large, hairy leaves, reddish stems and strong burrs that can trap bats and birds. It also get stuck in pets fur and can be painful.
To control burdock on your property:
- Cut tap root 8-10 cm below ground to remove completely.
- Mow or cut before flowering to prevent seeding.
Yellow flag Iris (Iris pseudacorus)
Yellow flag Iris (Iris pseudacorus) is an invasive plant that can grow on land, in riparian areas and in water. It forms dense mats that choke out the native species birds use for nesting. Floating seeds can spread long distances by water and underground rhizomes spread local infestations.
Yellow flag Iris on your property? Hand digging should be done carefully, as leftover and dropped root fragments can further the spread. The “benthic barrier” method is most effective. Plants are covered with heavy rubber matting and left for 70 days to smother themselves. Read the fact sheets linked below for more information or watch the videos for full instructions. Contact BIM if you need help with your management plan.
Giant hogweed (Heracleum mantegazzianum)
***CAUTION*** Giant hogweed leaves and stem hairs contains a clear, highly toxic sap that causes burns, blisters and scarring. The leaves are similar to carrot leaves but much larger, plants can grow up to 6m high.
Since BIM started controlling hogweed in 2016, sightings are rare. If you see giant hogweed, use extreme caution – do not touch it and please report your sighting to bim@bimbc.ca or 604-947-4255.
For more information please visit the links below.
Knotweeds (Fallopia sp.)
Knotweeds are far from dangerous, young shoots even have a delicious asparagus-like flavour fried up in butter. The reason knotweed is also known as the the “green zombie” is its ability to seemingly return from the dead, spreading further each time it’s cut down. Its roots can spread up to 20m laterally and 3m deep, lifting pavement to damage roads and sidewalks, and breaking through concrete to enter septic systems and foundations!
Because it is so easily spread (any live plant part, as small as 1cm, can sprout a new plant!) small patches of knotweed pop up in different spots each spring. But, after several years of mapping and treating knotweed annually, BIM is well on its way to eradicating knotweeds from the Island. Please help by reporting sightings of knotweed to bim@bimbc.ca or by calling 604-947-4255.
Check out the links below for more information and tips on removal of this invasive species from your own property.
Gorse (Ulex europaeus)
Apart from a few plants on Cates Hill, gorse is only found in the southern area of Bowen, along Cowan Point Drive to the golf course. Gorse is often mistaken for scotch broom because of their similar yellow flowers. From a distance, it can also be confused with rosemary but it’s many sharp, 2 inch thorns are unmistakable – and make it a real challenge to remove by hand.
Gorse is a fairly unique invasive species in the Lower Mainland but not worldwide – it covers 5% of the land area in New Zealand, and they spend millions each year trying to control it.
Bowen Island Municipality has been working on controlling the gorse infestation since 2019, with follow up treatments planned through 2024. Please report sightings of gorse to bim@bimbc.ca or by calling 604-947-4255.
Check out the links below for more information and tips on removal of this invasive species from your own property.
Daphne/Spurge laurel (Daphne laureola)
***CAUTION*** Daphne is prevalent on Bowen Island, particularly on the east side. You may have seen it in your own yard, and because of its waxy leaves, fragrant white flowers and black berries, mistaken it for a lovely ornamental shrub. But make no mistake – it is poisonous. Its sap can cause skin irritation and eye and throat irritation in enclosed spaces, and the berries, if eaten, can cause swelling, vomiting, weakness, coma and even death.
The fact that daphne thrives in shade and that its seeds are dispersed by birds make it difficult to control or contain. To control Daphne on your own property, wear gloves, long sleeves and goggles, pull small plants, dig up larger plants and cut the roots of plants you can’t remove at least an inch below ground. An Extractigator is available for loan from BIM to help pull larger plants, contact bim@bimbc.ca or 604-947-4255 to inquire.
For more information follow these links.
Scotch broom (Cytisus scoparius)
Scotch broom grows everywhere on Bowen, but thanks to the efforts of neighbourhood groups and the Weed Warriors, has been prevented from taking over large areas. As the broom busters say:
“Cut Broom in Bloom!”
Control broom on your own property by pulling small plants, digging up larger plants and cutting the roots of plants you can’t remove at least an inch below ground. An Extractigator is available for loan from BIM to help pull larger plants, contact bim@bimbc.ca or 604-947-4255 to inquire.
For more information follow the links below.
Euphorbia/Mediterranean Spurge (Euphorbia characias subsp. wulfenii)
***CAUTION*** Not an invasive on any of the official lists, but Euphorbia is popping up in ditches and along trails on the south side of Bowen. It’s a popular garden plant here because the deer won’t touch it – but you shouldn’t either! The milky sap causes photosensitivity, skin exposed to it will blister in the sun.
Japanese butterbur/giant coltsfoot (Petasites japonicus)
Japanese butterbur or is quite large and dramatic as an ornamental, but its underground stems allow it to spread rapidly, especially in moist streamside areas. Its large leaves also shade out other plants, which can leave bare ground and cause erosion problems.
This species is not yet on the noxious weeds list but is capable of invading sensitive ecosystems and is very difficult to get rid of.
Because Japanese butterbur is not yet widespread on the Island, it is a perfect candidate for an “early detection, rapid response” approach. In other words, we are working hard to eradicate this species before it becomes a problem.
Please don’t plant butterbur on your property and help us spread the word about this potentially invasive species!
- Noxious Weed Control Board
- Environmental Services
Disposal
Do not home compost invasive plant material, generally the temperatures are not hot enough to kill invasive plant seeds.
Knotweeds and hogweed should be double-bagged, sealed and disposed of in the regular garbage. Most other invasive plant material can be disposed of with green waste, but should be bagged to prevent further spread, especially when seeds are present.
Check with Bowen Island Municipality 604-947-4255 or Bowen Waste Solutions 604-947-2255 before putting any toxic, dangerous or invasive plant material out for curbside pickup.