A new study led by scientists at Durham University has uncovered that commercially sourced wildflower seeds, widely used in meadow creation and biodiversity projects, could unintentionally harm native wildflowers in Britain. Researchers focused on red campion (Silene dioica), a familiar and widespread species often included in wildflower mixes and found that plants from commercial seed suppliers are not the same as those growing naturally in the wild.

The importance of protecting native wildflowers

The team grew seeds from ten wild populations across Great Britain alongside two commercial seed sources in controlled garden experiments. They measured plant size, flowering patterns, and genetic variation. The results revealed clear differences where commercial plants were larger and more vigorous than wild ones, a sign that cultivation has already shaped them.

Although both commercial and wild plants showed high genetic diversity, the commercial ones were genetically distinct, suggesting they come from narrow or shared origins. This distinction matters because if commercial plants are planted on a large scale, they may cross-pollinate with local wildflowers.

Such gene flow could reduce or even erase local adaptations that wild populations have developed over centuries to cope with their unique environments. In the long term, these risks making populations less resilient to pests, diseases, or climate change, and may change the way ecosystems function.

Lead author of the study Dr Adrian Brennan of Durham University added: "The results show that it is important to consider within-species variation." The study confirms that even a common and abundant species like red campion is vulnerable to being altered by restoration practices. If this can happen to such a widespread wildflower, the risks may be even greater for rarer or more isolated species.

The findings underline the need for restoration projects to use local, genetically varied seed to maintain the natural patterns of diversity that underpin healthy ecosystems. With wildflower planting becoming more popular across the UK to support pollinators and enhance biodiversity, the research issues a timely warning.

The authors call for urgent, evidence-based guidelines to inform seed sourcing policies. They suggest that projects should follow the precautionary principle, unless proven otherwise, restoration efforts should use locally sourced seeds rather than mass-produced commercial stock. This work adds to a growing body of evidence that well-meaning restoration can have unintended consequences. By providing a case study of red campion, the research also offers a framework for assessing the evolutionary impacts of restoration in other wildflower species.

Source

'The potential adaptive and genetic impacts of habitat creation and enhancement using wildflower species: a case study of red campion (Silene dioica)', 2025, Adrian Brennan, Wayne Dawson and Stephen Willis, Plant Ecology and Diversity. An embargoed copy of the paper is available from Durham University Communications Office. Please email [email protected].

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