Invasive Species

Invasive Species

SAWIG is involved in invasive species management, identification and monitoring! Not only is our watershed coordinator a member of the PEI Invasive Species Council, but we also actively survey and manage invasive species in the late spring and summer! Not sure if what you’re looking at is invasive? Pin it anyway and we’ll check it out! See below for some common species, or at the invasive species council’s website!

What is an invasive species?

Canada has a wide variety of species of plants and animals; the biodiversity of our country is amazing! Unfortunately, not all of these species are native to our area; in fact, there are some that should not live here at all!

To put it simply, an invasive species is...

any species that is not native to an area and threatens the environmental, economic or social health of the area.

(PEI Invasive Species Council, 2012).

How do invasive species get here?

Some of these plants and critters catch a ride from other parts of the country, or the world through various means; some mooch a lift on humans, in cargo, on the bottom of boats or in ship ballasts. Not all of these non-native species are a problem, but there are some that can pose serious risks to native flora and fauna.

What is the problem with invasive species?

Once a species is removed from its natural area (ecosystem), it may no longer have any predators or ways to keep the population in check. This means a particular species may be free to quickly reproduce, grow and take over entire areas once populated by native plants or animals. For this reason, invasive species often out-compete native species.

Purple Loosestrife photo: Mike Ogden

Who is Causing Damage Here?

While all invasive species typically cause damage the PEISC has a prioritized list of the invasive species residents of Prince Edward Island should watch out for:

Yellow Flag Iris

Yellow Flag Iris is an ornamental planet which originates in Europe, Northwest Africa and Western Asia. It grows it moist ground and will be found in ditches, wetlands, and around waterways. You can identify Yellow Flag Iris by its sword shaped leaves which range from 0.5m- 1.5m long and 1-3cm in width with a raised ridge in the middle of the leaf.

Yellow Flag Iris


The PEISC recommends completely digging the plant from the ground. Care must be taken to remove all aspects of the plant, roots, rhizomes etc. as the plant will grow again from the remainder. Mowing or cutting has been proven effective as it inhibits photosynthesis eventually killing the plant. In regards to both of these containment efforts the site must be monitored annually to ensure the plant has been eradicated.

Wild Cucumber

Wild Cucumber grows in most areas across PEI, alongside trails, in fields or in forest areas. Wild cucumber is a vine that grows on other shrubs and trees and can choke out smaller plants. It can easily by identified by its spiky fruit, and its leaves with have 5 lobes and a heart-shaped base.

Leaves of Wild Cucumber


Mowing or cutting the plant back in the spring is the best way of ensuring plant morality.

Scotch Broom

Scotch Broom grows in open habitats such as, fields, meadows or yards. It has an extensive root system so becoming very difficult to eradicate once established. Scotch Broom originated from Europe and was brought over originally as an ornamental plant. It has also been used as a coffee alternatives and used for medicinal purposes. Scotch Broom is identifiable by its yellow, pea-like flowers which bloom from May to June. The leaves near the base of the plant also contain 3 leaflets and it has a woody, angled stem.

Flower and leaves of Scotch Broom


Scotch Broom is difficult to manage as its seeds can remain viable in the soil for up to 30 years. Digging is only an option for small infestations. The best management strategy is to cut the plant to ground level and cover with thick black plastic.

Purple Loosestrife

Purple Loosestrife grows along waterways, choking out and destroying natural environments. It can be identified by its purple to pink flowers (5-7 petals) which grow on “spikes” which are 10-40cm long. Purple Loosestrife’s flowers bloom from July to September.

Purple Loosestrife


Digging is the most effective method of eradicating infestations of Purple Loosestrife. When digging, care should be taken to remove as much of the root system as possible to limit regrowth.


Periwinkle can be found at ground level in forests and over shaded areas. It grows and spreads rapidly choking out most native ground cover plants. Periwinkle can be identified by its glossy, evergreen leaves and its pale blue flowers which are 3cm wide and have 5 petals. Periwinkle flowers bloom from May until June.


To remove periwinkle, dig up the whole plant. Make sure that the whole root system has been removed from the ground as any remaining pieces of root will be able to grow into a new plant. In order to do this most effectively, remove plants when soil is damp or soft.