Pomegranates in Brussels: how plants are moving north
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Belgian botanist Roosmarijn Steeman observed pomegranate and date plants growing in Brussels, prompting a four-year project called FloraBru to catalogue wild plants in the city.
Steeman and other researchers are finding increasing numbers of Mediterranean and even subtropical plants thriving in urban environments like Brussels, Ghent, Antwerp, and parts of the UK, Germany, and Czechia.
These plants benefit from the urban heat-island effect, where concrete and stone retain heat, creating warmer microclimates, and they often prefer rocky environments common in cities. While climate change creates conditions that allow these plants to survive, most plant dispersal isn’t directly caused by warming temperatures. Migrating birds carry seeds over considerable distances, a 2025 Royal Society study using GPS trackers showed thrushes can move seeds tens to hundreds of kilometres.
However, human activity is the primary driver, as seeds attach to clothing, shoes, and vehicles during travel. Filip Verloove of the Meise Botanic Garden discovered that trade patterns predict the arrival of non-native plants. He traced South African weed species growing near grain docks in Ghent, Belgium, back to originating in Western Australia and travelling via Australian grain shipments.
Verloove suggests experts can now monitor a country’s trade partners to anticipate the introduction of new plant species, and some introduced plants, like the butterfly bush, can become invasive and even damage structures.
