Butterfly Bush is a shade-intolerant deciduous to semi-evergreen, multi-stemmed shrub introduced from Asia. The plant is celebrated in horticulture for its fragrant, attractive butterfly-pollinated flowers and its adaptability to a wide range of soil types. Unfortunately, butterfly bush has escaped cultivation in southern BC and is now considered an invasive species.
How does it spread?
Butterfly bush spreads by easily dispersed seed and by detached root or stem pieces. Seeds can be dispersed by wind, water, wildlife, and humans. Butterfly bush is a prolific seed producer; a mature plant can reach 5 m in height, and produce 100,000 to 3 million seeds annually. The plant has a very fast growth rate, and often flowers in the first year of growth.
Where would I find it?
Butterfly bush prefers mesic to dry areas and rocky slopes in the lowland zones of southwestern BC, the lower Fraser Valley and in southeastern Vancouver Island. It is often found in sensitive Garry Oak ecosystems and in burnt forest areas, riparian corridors, rural/urban disturbed areas, along railways, roadsides, water courses, river banks, sea coasts and wetlands, and near cliffs, building sites, and waste areas.
What problems does it cause?
Butterfly bush often escapes cultivation and spreads rapidly. Once established, plants can quickly establish monoculture stands that dominate, shade out, out-compete or displace native, agricultural, plantation and forestry related species. Uprooted plants are easily transported along watercourses and are known to form blockages in culverts, contributing to bank erosion.
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