Introduced Species: New plants colonizing Sweden

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Introduced Species
New plants colonizing Sweden

      In the states we frequently hear about introduced and invasive species brought here from Europe, Asia, and around the world. However, many species of plants and animals have also been introduced in the opposite direction, and some North American natives have become invasive in Europe. In my limited travels around Sweden I did not observe any major problems with invasive species. Nevertheless, I did see and photograph many nonnative plants in Sweden, including some that are very familiar back home.

      Some introduced species are easy to recognize, such as Himalayan blackberry (Rubus armeniacus), which is also invasive in the states, and quite delicious. The common name suggests that it is a cold-hardy plant from the Himalayans, but actually it is native to Armenia, as noted in the botanical name, so it prefers warm, Mediterranean climates. From my home in Montana I drive 500 miles to the toasty warm depths of Hells Canyon on the Idaho-Oregon border to harvest my yearly supply of Himalayan blackberries. I've also enjoyed the juicy fruit in New Zealand. Himalayan blackberry has truly established a global presence! Thus it is no surprise to see the brambles growing wild in the southernmost parts of Sweden. Those equatorial waters that make Sweden unexpectedly warm actually give southern Sweden a semi-Mediterranean climate. In Trelleborg, Sweden's southernmost town, there are even palm trees, although none that seemed particularly happy to be there, in my opinion. Not surprisingly, Himalayan blackberry also found its way there, growing quite prolifically in places. Invasive or not, I'll enjoy this plant anywhere!

Ornamental touch-me-not: Impatiens glandulifera.       One plant that was apparently introduced from the Himalayan region is ornamental touch-me-not (Impatiens glandulifera), also known as Himalayan balsam. It was evidently introduced as an ornamental for its beautiful flowers, yet has become something of a problem plant in Sweden. Based on my observations, however, the plant seemed dependent on human habitats, growing around farmsteads and in manure piles, rather than taking over wild Sweden.       I encountered several North American plants growing wild or feral in Sweden. Large-leaved lupine (Lupinus polyphyllus) is native to the Pacific states and Canada, although I wasn't previously familiar with that species. Canada goldenrod (Solidago canadensis) is an obvious import, at least in name, and it is considered invasive in Europe.

      Just looking at a plant, it would be difficult to predict whether it is native, and perhaps circumpolar, or introduced. For example, snowberries (Symphoricarpos albus) seem just as natural as anything else growing in Sweden if you don't know that they are actually native to North America. Originally introduced as ornamentals, snowberries have since gone feral in Sweden. I had to read about each species to check on its original native range.

      Scroll down the page to see some of the introduced species that have found fertile ground in Sweden.