New research sheds light on why plants change sex

Plants with a particular breeding system change their sex depending on how much light they receive, new scientific research has revealed.

Cranesbill (Pixabay image)

The ability of plants to flower one year as male and the next as female, or vice versa, is well documented in ‘dioecious’ plants, however the causes of this ability to change gender have been largely unexplored in ‘gynodioecious’ plants until now.

Gynodioecy is a breeding system that is found in certain flowering plant species in which female and hermaphroditic plants coexist within a population. Gynodioecy is the evolutionary intermediate stage between hermaphrodite plants (each flower has both male and female parts) and dioecious populations (each plant having either only male or female flowers).

The ability to change sex in response to the environment has been studied extensively in dioecious plants but this new research has revealed that gynodioecious plants also change sex depending on their environment.

The results of a four-year study by researchers at the University of Lincoln, UK, show that the level of light received by the plant has a significant effect on sexual expression and reproductive output. The study found that in habitats with high levels of light, plants were more likely to change their sexual expression, and the researchers believe this is because sex lability (readiness to change) is costly and related to the availability of resources.

Dr Sandra Varga, Marie Curie Research Fellow at the University of Lincoln’s School of Life Sciences, led the research. She explained: “The evolution and maintenance of such sexual polymorphism has been investigated by evolutionary biologists for decades. It is one of the most important developments in the evolution of plant breeding systems. However, understanding the causes and consequences is challenging because so many different factors might be involved in the process of changing from one sex to another.

“Our research clearly showed that sex expression was changeable over the course of the study, and was directly related to light availability.”

Throughout the study, the researchers observed the behaviour of 326 different plants for four years and transplanted them between locations with both high and low light levels to replicate the different environments they may encounter. For example, the wood cranesbill plants used in the study can often be found under dense forest canopies and in meadows and road verges.

The researchers monitored how the sex and reproductive outputs of the plants differed depending on their location, to garner a deeper understanding of how their behaviour is altered by their environment.

The paper is published in the American Journal of Botany and is available to read online.

Heritage Lottery funding to safeguard Lincolnshire plants

A new Heritage Lottery Fund supported project aims to inspire young people to become the botanists of the future, helping to safeguard and improve our understanding of plants and the environment.

Pioneered by Lincolnshire Naturalists’ Union, Lincolnshire Wildlife Trust, the Sir Joseph Banks Society and the Natural History Museum, the project is called ‘Lincolnshire Plants – Past and Future’. The University of Lincoln will support the project by studying the genetics of these plants.


A development grant of £21,400 from the Heritage Lottery Fund (HLF) has already been secured to begin setting up the project. Once this development phase is complete, a larger grant of £473,100 has been earmarked by HLF for a three year project.

This larger grant will partly be used for a range of lifelong learning events and public engagement, a key aspect of which is to help young people connect with wildlife and develop botanical skills like plant identification, wildlife recording and the careful collection of important specimens.

The project will fund the creation of a contemporary collection of Lincolnshire plant specimens, inspired by a collection created by Sir Joseph Banks, the eighteenth century Lincolnshire naturalist who famously voyaged around the world with Captain Cook. This will compliment an older collection currently preserved by Lincolnshire Naturalists’ Union.

Over the last 150 years the Lincolnshire Naturalists’ Union has been compiling a huge collection of over 9000 plant specimens, including some of Lincolnshire’s rarest plants. Such a special archive can provide lots of information about climate change, plant genetics and nature conservation. However, with no proper storage facilities available in Lincolnshire the collection is now at serious risk of deterioration. Fortunately, as part of the lottery funded project the Natural History Museum in London will now look after the collection, securing it safely in facilities designed specifically for the protection of plant specimens. The Natural History Museum will also professionally catalogue and document the specimens, unlocking a treasure trove of vital environmental information.

These plant collections will allow scientists to study changes in our environment over the last three centuries, dramatically improving our understanding of the natural history of Lincolnshire and informing future environmental decisions. Scientists at the University of Lincoln hope to study the genetics of the specimens once they have been catalogued.

Chris Manning, Chair of the Project Steering Board and from Lincolnshire Naturalists’ Union, said: “This project is a wonderful opportunity to inspire young people with nature and improve our knowledge of Lincolnshire’s natural history. We need new botanists to help us understand the impact of climate change and to champion the knowledge we can gain about our environment from studying plants.

“Once our past and present plant collections are catalogued and stored by the Natural History Museum we will have a huge resource to help botanists and scientists better understand our environment.”