My flowers and stems turn brown in the winter,
Hiding beside roads and alongside the river.
When spring rolls around, I’m purple and green,
And my bushy tall stands are a sight to be seen!
This invasive’s arching branches make it easy to spot, even without its showy flowers. Butterfly Bush, despite its misleading name, is actually a harmful species to butterflies overall! While Butterfly Bush does produce pollen that butterflies enjoy, that pollen can only be utilized by adult butterflies, and does not support its other lifeforms. Not only do butterflies not tend to lay their eggs on Butterfly Bush, native caterpillars can’t eat the leaves, so any eggs laid on these bushes won’t survive. By attracting native butterflies away from their native, safe wildflowers, this invasive is harming butterfly populations.
Butterfly Bush is native to China and was introduced to North America as an ornamental plant. Unfortunately, it remains a popular shrub for well-meaning gardeners hoping to attract butterflies to their gardens. Some plant stores and garden centres also continue to sell this species throughout the Sea to Sky. Butterfly Bush is very resilient, grows in various conditions, and is found lining the Sea to Sky Highway from Lions Bay up to and past Squamish.
During the summer, Butterfly Bush is most easily identified by its large clusters of purple, pink, blue, white, red, or orange flowers. The flowers mature into brown capsules that remain attached to the cluster and open at one end to release their seeds. This invasive’s arching stems can reach 5 m tall, developing a gray-brown, peeling bark as they mature. Its green to blue-gray leaves are long, pointed, typically 10 – 30cm long, and covered in fuzzy hairs on the undersides.
Butterfly Bush reproduces mainly by seed but is also able to sprout from cuttings. Each flower cluster can produce up to 40,000 seeds after the plant’s first year of growth, which remain viable in the soil for 3-5 years. These seeds are spread by the wind and water away from the parent plants. The popularity of Butterfly Bush in the gardening world has led to much of its global spread.
Butterfly Bush’s impressive rate of seed production makes it a quick spreader. As mentioned earlier, Butterfly Bush is detrimental to populations of native butterflies. This affects the entire ecosystem, as it decreases the amount of pollinators available to our native wildflowers as well. An overall loss of local biodiversity comes as a result of this. Butterfly Bush also alters the levels of Nitrogen and Phosphorous in the nearby soils, which further displaces native species.
Without its flowers, Butterfly Bush is often confused with the native Rose Spirea, as well as with exotic plants in the California Lilac family. Rose Spirea, while having a similar spike of mature flowers to Butterfly Bush, has tiny dry brown fruits that give the spikes a fuzzy appearance. Several different species of California Lilac have very similar flowers to Butterfly Bush, but they tend to have smaller, shinier leaves. California Lilac also tends flowers earlier in the season than Butterfly Bush.
Per SSISC’s Invasive Plants Priority List, Butterfly Bush is listed as a species to contain in Squamish, to eradicate in Whistler, and is on the Prevention Watchlist in Pemberton. We rely heavily on reports from the public to understand the current distribution of plants in the Sea to Sky and prevent their spread. With that in mind, we invite you to keep your eyes peeled for Butterfly Bush and report any sightings.
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