Although eye-catching, hardy, and seemingly helpful to butterflies and other pollinators, this plant is far from beneficial.
My flowers and stems turn brown in the winter,
(Photo credit: Wikimedia Commons)
Hiding along roads and the river,
When spring rolls around, I’m purple and green,
And my bushy tall stands are a sight to be seen.
Butterfly Bush (Buddleja davidii) is an invasive plant that has escaped the confines of gardens in southern BC. It is native to China and was introduced to North America as an ornamental plant because of its large purple tubular flowers, believed to attract butterflies.
However, Butterfly Bush’s resistance to garden insects makes it a poor habitat for the caterpillars and other critters needed in nature to sustain the food web. This is especially true on our rivers where insects feeding on native shrubs and trees fall into the water to feed salmon and other fish. In fact, one of the impacts of Butterfly Bush on rivers is that it crowds out native vegetation, such as willows, that 
provide valuable habitat for many of our native butterflies. Moreover, their nectar is only suitable for adult butterflies, so they don’t actually support butterflies throughout their whole life cycle. Thus, Butterfly Bush ultimately harms butterfly populations by decreasing both habitat and food availability.
Nonetheless, as Butterfly Bush is a hardy shrub that can be grown in various environments, it has been a popular choice for gardens and landscaping. Indeed, its ability to withstand challenging environmental conditions has allowed it to spread outside of cultivated areas to forests, meadows, riparian, and coastal habitats where it competes with native species like Douglas-fir. Moreover, flower clusters can produce over 40,000 seeds, aiding the species’ reproduction and ability to form dense monocultures.
Butterfly Bush in winter
As hinted in the riddle, the deciduous shrub has tall arching branches that can reach 5 m in height. You can easily identify the plant by the showy flower spikes, which are often purple with an orange centre, and bloom mid-summer. They also have lance-shaped opposite leaves that are distinctly green to blue-gray above and whitish below due to fuzzy hairs.
Luckily, there are many native ornamental plants that you can plant as an alternative, including Red-flowering Currant and Ocean Spray. You can also contain Butterfly Bush by cutting the plat at the base and placing the branches in the garbage (not the compost!). Note that the stumps are likely to resprout, so consider covering them with a thick plastic bag or mulch after cutting.
As SSISC contains populations in Squamish, eradicates populations in Whistler, and prevents the spread of populations in Pemberton, we ask that you report any sightings here.
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