20 July 2025, in Finland

It’s likely that every place on earth now has invasive plants and many of them are the same species popping up everywhere. We’re now in Finland where their invasive plants list includes two that are also invasive in Pennsylvania — giant hogweed (Heracleum mantegazzianum) and rugosa rose (Rosa rugosa) — but we’ve also seen two species that are invasive in Finland and don’t even grow wild in PA.

Lupines (Lupinus) are a beautiful flowering genus of 199 species, most of which are native to North and South America. Often cultivated in gardens, they’ve escaped to the wild in Scandinavia and New Zealand and are now invasive.

Garden lupine (Lupinus polyphyllus) is native to western North America from Alaska to Utah and was intentionally planted to beautify roadsides in Finland.

But now it is everywhere. I thought these flowers by the railroad were part of a beautification project. Nope. They’re invaders.

Himalayan balsam (Impatiens glandulifera) is an annual plant with high seed production that followed the same trajectory as giant hogweed and Japanese knotweed.

In the UK, the plant was first introduced in 1839, at the same time as giant hogweed and Japanese knotweed. These plants were all promoted at the time as having the virtues of “herculean proportions” and “splendid invasiveness” which meant that ordinary people could buy them for the cost of a packet of seeds to rival the expensive orchids grown in the greenhouses of the rich.

— Wikipedia: Himalayan Balsam

Indeed Himalayan balsam is splendidly invasive but because it prefers a cooler climate it invades the northern latitudes and does not grow wild in PA.

Though it is an annual it produces lots of seeds which pop when the seed pod is touched.

You might notice its resemblance to our native jewelweeds — for instance yellow jewelweed (Impatiens pallida) or pale touch-me-not — whose seed pods also pop.

Read more about invasive species in Kuopio, Finland near where we’re visiting. The Spanish slug is on their list. Eewww!