Floral Survival in a Changing Climate

If you go outside at this time a year, there is a good chance you’ll stumble upon the common primrose (Primula vulgaris). Its yellow blooms are a sweet and familiar site here in the UK, yet due to climate change, spring is advancing, and they are flowering earlier and earlier. [1] Along with its native wild range in shaded woodland, Primula species are also popular with gardeners.

The common primrose (P. vulgaris) had greater stress tolerance than the garden hybrids studied and other wild varieties such as Cowslips (Primula veris) pictured here| Credit: Leonora Enking (CC BY-SA 2.0)

A study by Lewis and Cameron (2019), has revealed that the more extravagant blooms common in gardens are particularly susceptible to climate change [2]. Interestingly, there was no clear divide between wild and cultivated varieties. Instead, the results show a scale of stress tolerance that strongly correlates with floral complexity [3]. For example, Primula’ cottage cream’ has a slightly more orange centre that P. vulgaris, yet is structurally very similar, and also shows enhanced stress tolerance.

“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.”

Dr Ross Cameron, Senior Lecturer in Landscape Management, Ecology and Design at the University of Sheffield

Research into the responses of garden plants to abiotic stresses is vital to buffering urban areas against future climate change. Green infrastructure such as urban gardens are capable of partially mitigating adverse climate impacts, yet are also highly susceptible to adverse conditions and abiotic stresses. In particular, the study by Lewis and Cameron (2019) focused on waterlogging, drought and rapid oscillation between the two, as these conditions are likely to increase in frequency as the global climate changes.Urban gardens and the flora they contain are also vital for many ecosystem services, which range from pollination to seed dispersal and habitats for wildlife. Green spaces also contribute to human wellbeing by encouraging healthy, active lifestyles and improving mental wellbeing [4].

This study implies that, in order to maintain garden ecosystems and the services they provide, planting should be adapted to the species best able to adapt to the changing climate [3]. Similar trends were also observed in Pansies and Petunias.

“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.”

Dr John David, Head of Horticultural Taxonomy at the Royal Horticultural Society

[1] Emorsgate Seeds (2020). Primula vulgaris – Primrose | Wild Flowers. [online] Available at: https://wildseed.co.uk/species/view/107 [Accessed 22 Feb. 2020].
[2] Lewis, E., Phoenix, G.K., Alexander, P. et al. (2 more authors) (2019) Rewilding in the garden : are garden hybrid plants (cultivars) less resilient to the effects of hydrological extremes than their parent species? A case study with Primula. Urban Ecosystems. ISSN 1083-8155, https://doi.org/10.1007/s11252-019-00865-7
[3] Armour, S. (2020). Less flamboyant flowers are more resilient to climate chaos, research shows. [online] Sheffield.ac.uk. Available at: https://www.sheffield.ac.uk/news/nr/less-flamboyant-flowers-more-resilient-climate-chaos-1.877894 [Accessed 22 Feb. 2020].
[4] M. Camps-Calvet, et al., Ecosystem services provided by urban gardens in Barcelona, Spain: Insights for policy and planning, Environ. Sci. Policy (2016), http://dx.doi.org/10.1016/j.envsci.2016.01.007