Download Article - Invasive Species Council of BC

Weed of the Week: Oxeye Daisy
During the summer months, whether you enjoy a stroll or a bike ride along the
meadows and roadside paths of southern or interior British Columbia, you’re likely
to notice an attractive abundance of oxeye daisies (Leucanthemum vulgare) in
bloom. Many people consider oxeye daisy to be a pretty wildflower, but
wildflower does not mean native; in fact, oxeye daisy is not a native wildflower in
BC, but an invasive plant.
With origins in Europe and introduction in the 1800s, it’s easy to see why people
believe oxeye daisy is a native wildflower. Oxeye daisy is actually an out-ofcontrol perennial, considered regionally noxious under the BC Weed Control Act.
Invasive plants grow rapidly and spread quickly, causing damage to the
environment, economy and our health. They are also the second greatest threat
to biodiversity after habitat loss, according to the International Union for
Conservation of Nature (IUCN).
In Greek mythology, the name ‘oxeye’ was a flattering name affectionately
given to Hera, the Queen of Olympian gods and later given to this pretty daisy.
Despite its beauty, this invasive plant can greatly alter the productivity of a
pasture by replacing grasses, especially in an overgrazed area with low soil
fertility, thereby creating economic losses. Worldwide there are about 200
species of daisy that the Scots called "gools". The farmer with the most gools in
their wheat field paid an extra tax. Due to its unpleasant taste, most grazers
avoid this plant, leaving it to spread easily within grazed grasslands, pastures,
and rangelands. Infestations decrease forage for wildlife and local plant
biodiversity.
Even if some plants are eaten, as many as 40% of the seeds consumed by cattle
may remain viable after passing through the digestive tract. Tests have shown
that 82% of buried seeds remained viable after six years, and one percent were
still viable after 39 years. These plants have also shown to carry several crop
diseases including the yellow dwarf virus of potatoes.
Oxeye daisy plants aggressively reproduce by seed and underground stems. A
single plant produces 26,000 seeds and dispersal from parent plants lead to new,
dense infestations that quickly spread. Commonly found dotting low to midelevations in grasslands and dry to moist forests, this unwanted invader is present
in the Kootenays, Lower Mainland, Vancouver Island, and of major concern in
the Cariboo, Okanagan, Peace River, Thompson, and Omineca. Oxeye daisy is
a considered an invasive plant in 13 crops in 40 countries!
Oxeye daisy has daisy-like flowers at the end of course, slender stems, with lower
spoon-shaped leaves. The young leaves are said to be eaten in salads in Italy.
Central yellow disks grow 10-20 millimetres wide and white ray flowers 1-2
centimetres long. Oxeye daisy is often confused with the ornamental Shasta
Daisy (Chrysanthemum maximum), which has larger yellow disk (2-3 cm) and
white ray flowers (2-3 cm).
Shasta daisy is a good alternative to oxeye daisy, and if you want to bring nature
back to your garden with wildflowers, try to choose wildflower seed mixes
carefully, as many contain invasive plants like oxeye daisy. Wildflower mixes do
not tend to list the species they contain, and colorful photos on package covers
mislead consumers into purchasing invasive plant seeds that are native to
Europe and other parts of North America, but not BC. Avoid wildflower mixes
unless you are buying them from a reputable native plant nursery that has
collected seeds locally.
Once established, oxeye daisy can be difficult to control or eradicate. Help your
community protect local resources by managing invasive plants. To find out
more about invasive plants in your area or to seek alternative plants, visit
www.invasiveplantcouncilbc.ca or phone (250) 392-1400 or 1-888-WEEDSBC