Native Plants in Research: Allium cernuum – Climate Change and Changing Flower Color

Allium cernuuum, Nodding Onion

The nodding onion was recently featured in a research paper about how climate change is affecting the colors of flowers. Our own native, Allium cernuum was one of 12 species studied.

The research, by lead researcher Cierra Sullivan out of Clemson University’s Department of Biological Sciences showed a link between climate change and an increase or decrease in floral pigmentation in 12 species of plants.

The research examined herbaria specimens of 12 species covering a span of 124 years. The specimens were analyzed for pigmentation as well as location and date of collection. The location and date information was used to determine the climatic conditions of the time.

Basically Sullivan’s research found that with an increase in temperature, anthocyanin-based pigmentation in flowers in the 12 species decreased, while with an increase in aridity the pigmentation of these 12 species of flowers increased.

Allium cernuum herbarium specimen from the Brown University Herbarium found in the Consortium of Northeast Herbaria.

Anthocyanin pigments are those chemicals in a flower or leaf that show the blue/purple/pink spectrum of color. These pigments are responsible for protection from the sun and other abiotic stressors such as dessication and heat regulation. Additionally anthocyanic pigmentation may play a role in the ecological relationships between pollinator and pollination as well as herbivory.

We know that pigment variations within a taxon can happen naturally, in fact, this is where so many cultivars start. However, this research indicates that climate change is causing plants to change flower colors. The results of this research are raising awareness that the resulting pigmentation changes associated with climate change have the potential to impact plant-animal interactions and overall plant reproductive performance.

Listen to a summary of this research on this episode of Science Friday.

Check out herbarium specimens for yourself using these online resources used by Sullivan and her co-researchers:

Southeast Regional Network of Expertise and Collections

Consortium of Pacific Northwest Herbaria

Consortium of California Herbaria

Consortium of Northeast Herbaria

About the Researcher: Cierra Sullivan received her B.S at Christopher Newport University in Newport News, Virginia, with a minor in psychology. At Clemson she is working towards her Ph.D. in evolutionary plant ecology with Dr. Matthew Koski. Her research investigates the ecological correlation of leaf variegation and flower color variation in plant species and how this phenotypic variation may affect plant fitness.

Reference: Sullivan, C. N., & Koski, M. H. (2021). The effects of climate change on floral anthocyanin polymorphisms. Proceedings of the Royal Society B288(1946), 20202693.

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