Invasive Evil Twins

Invasive Evil Twins
Invasive Evil Twins

Many non-invasive exotic species in the Sea to Sky area are entirely harmless, either staying put in the gardens they’re planted in, or contributing to a functional ecosystem. However, some are either closely related to an invasive species or look very similar. Knowing the difference can be the key to helping prevent the spread of invasive species in the Sea to Sky!

Here are a few examples of plants that have “evil” invasive twins:


Perennial Baby’s Breath vs. Annual Baby’s Breath

Perennial Baby’s Breath (Gypsophila paniculata) is invasive, while Annual Baby’s Breath (Gypsophila elegans) is non-native.

These two plants are very closely related to one another, and nearly identical at a glance. Their flowers are extremely similar, with Annual Baby’s Breath having slightly showier flowers. The main difference between the two species is their growth habits.

As their names suggest, Perennial Baby’s Breath is a perennial species, with individual plants that can survive year after year, whereas Annual Baby’s Breath is an annual species with individual plants that die off each year. This distinction is what makes one invasive while the other is simply non-native.

Perennial Baby’s Breath can grow its population size exponentially each year. Since plants survive multiple years, they produce seeds many years in a row and quickly take over dry, rocky areas.

Invasive Perennial Baby’s Breath is not currently found in the Sea to Sky. If you think you’ve spotted, please report it.

California Poppy vs. Welsh Poppy

California Poppy (Eschscholzia californica) is considered invasive in the Sea to Sky, while Welsh Poppy (Papaver cambricum) is non-native and non-invasive.

These two species, while they look quite similar, aren’t as closely related as some of the other species in this list. While both species are within the Poppy family, they are native to opposite sides of the globe. Welsh Poppy is native to Western Europe, while California Poppy is native to Mexico and the southwestern United States.

California Poppy has bright orange flowers with satin-like petals that close up on dark days and overnight. Welsh Poppy’s flowers are typically yellow or orange, with a distinct seed pod growing from the centre. When the flowers are finished blooming, the seed pods remain at the ends of the stalks, and disperse the seeds through tiny holes on the tops of the pods. This species reproduces prolifically, with seeds that burst from the seed pods and are catapulted up to 2 m away from the parent plant.

In its native range, California Poppy blankets the dry hills in gorgeous orange flowers from February to May. California Poppy is also often utilized in wildflower seed mixes, which could aid spread. Please avoid planting invasive species – you can browse through this page to learn more.


Yellow Flag Iris vs. Blue Flag Iris

Yellow Flag Iris (Iris pseudacorus) is invasive, while Blue Flag Iris (Iris versicolor) is non-native/exotic.

These two species are easy to tell apart while in bloom but not so much during the rest of the year. Yellow Flag Iris and Blue Flag Iris are very closely related, as evident by their similar size, leaf shape, height, and flower shape. However, despite these similarities, they behave quite differently from one another.

While Blue Flag Iris makes a great addition to a damp area in a garden, Yellow Flag Iris is an aggressive invasive. Yellow Flag Iris quickly spreads throughout waterways, forming dense mats of rhizomes. It is toxic to both humans and wildlife and outcompetes many native species that the ecosystem relies on. Skin contact with its leaves is also known to cause irritation.

Blue Flag Iris, on the other hand, grows more slowly and takes a long time to form a dense stand with its rhizomes. Native to eastern North America, it has quite a few pollinators and native pests that overlap with the West Coast; it is also edible to wildlife, unlike its yellow cousin.

Field Bindweed vs. Morning Glory

Field Bindweed (Convolvulus arvensis) (also commonly called Morning Glory) is invasive, while true Morning Glory (Ipomoea spp.) is non-native.

This comparison gets a bit more complicated. To help, the invasive plant that is commonly called ‘Morning Glory’ will be referred to as Field Bindweed here. True Morning Glories are part of the genus Ipomoea (relatives of the sweet potato), while Field Bindweed is in the genus Convolvulus (nightshade family). Despite their similarly-shaped flowers, these two groups of plants aren’t very closely-related.

True Morning Glories, including Sweet Potato Vine, generally have more heart-shaped leaves and many different flower colours. While also a vine, this group of plants is not nearly as aggressive of a grower as Field Bindweed is. They grow much slower and are not considered invasive.

Invasive Field Bindweed, if allowed to establish, will form a deep, extensive network of roots and rhizomes that are extremely difficult to remove. This species has leaves that are arrowhead-shaped and only has flowers that are white or occasionally tinged pink. Field Bindweed grows very quickly, climbing over all obstacles in its path.


Are you confused yet?

If you think you’ve spotted one of the invasive plants presented in this article, don’t hesitate – report it to us!

Spread the love

Add Comment

Your email address will not be published. Required fields are marked *