Plants with smaller, simpler flowers are more resilient to the impacts of climate breakdown than those with more flamboyant, showy flowers, according to a new study.
Researchers at the University of Sheffield and the Royal Horticultural Society (RHS) investigated how different Primula species and cultivars responded to flooding and drought conditions, based on climate prediction models. Their results, published in the journal Urban Ecosystems, showed that varieties with smaller, simpler flowers had higher survival rates than cultivated forms of Primula with larger blooms when exposed to a range of stressful scenarios.
The most resilient variety was Primula vulgaris (primrose), a species found across Europe. This proved to have a greater resilience to stress than highly-cultivated garden hybrids such as Primula FORZA and the Primula Alaska series. However, they did find that another cultivar, Primula Cottage Cream, which superficially resembled Primula vulgaris, was more tolerant to stress than native species such as Primula elatior and Primula veris.
The findings suggest that those plants that dedicate less energy to producing large and colourful flowers are better able to withstand the extreme conditions associated with the climate crisis, and offer guidance to gardeners and landscape designers looking to create more resilient green spaces.
Dr Ross Cameron, Senior Lecturer in Landscape Management, Ecology and Design at the University of Sheffield, who led the project, said: “This is not simply a case of species being better than cultivated hybrids, as our Primula Cottage Cream plants outperformed other native Primula species used within the study. Rather, the results seem to relate more to the amount of energy plants invest in flowers.
“We have noted similar trends in Pansy and Petunia, with cultivars possessing larger flowers losing quality more rapidly than those with smaller flowers. We believe that the more highly-bred cultivars with larger flowers or even unusual colours are investing more in these traits, and in turn, sacrificing resources that help improve tolerance to stress. It seems to be a ‘trade-off’ between these factors.
“Plant breeders and nurseries have done much over recent decades to produce more compact and sturdy plants that tolerate wind, but they now need to consider ways to increase tolerance to more extreme soil wetting and drying. This includes the capacity to cope with rapid oscillations between these wet and dry conditions, which is becoming more common with climate change.”
Dr John David, Head of Horticultural Taxonomy at the Royal Horticultural Society, said: “Although this work is preliminary, it has implications for the garden plants, and perhaps even wild species, that will survive against the background of a changing climate. We may need to better appreciate plants with smaller, simpler flowers, as our larger, heavier-bloomed or double forms of flower that are common in gardens today may not have the required resilience to tolerate future weather patterns.”
The research was based on a PhD study conducted by Dr Emma Lewis and sponsored by the RHS.