A carpet of glossy yellow Celandines means spring. It is interesting to note how often early and late seasonal plants are yellow. Glossy yellow flowers are particularly eye-catching in winter sunshine. However, it is not what humans see that is important to the plant. Bees can see ultraviolet patterns that we cannot see. Ranunculaceae may seem a commonplace plant family, yet time and time again, science reveals its extraordinary floral tactics are worth closer investigation.
I noticed my first Lesser Celandines (Ficaria verna) in early January. These first specimens looked particularly bedraggled. They were particularly hard hit by this year’s harsh winter frosts. Some yellow petals had lost some of their gloss revealing patches of white starch.
Local Lesser Celandines now seem to be trying to stage a comeback. There are numerous patches of recognisable leaves. Their first forays seem tentative. Most leaf patches are pushing out a solitary yellow flower. Are they sending out an advance scout to test the ambient temperature and presence of potential pollinators?
The early appearance of Lesser Celandine has long inspired writers and poets. Wordsworth dedicated no fewer than 3 poems to this spring harbinger. Its glossy yellow petals have also attracted the attention of scientists. John Parkin wrote about Ranunculus petals back in 1928. (For Lesser Celandine was known as Ranunculus ficaria rather than Ficaria verna then). He challenged other botanists to find the glossy characteristic in other flowers. It seems none provided satisfactory challengers.
Seeing with Bees’ Eyes
Modern science and photography have moved on. My Lesser Celandine photo (below) reveals some of the petals’ gloss and patterns visible to the human eye. Bjørn Rørslett’s photographic website gives us an opportunity to see flowers as bees see them. Lesser Celandine demonstrates a very strong ultraviolet pattern. The petals have oily glands towards their base. This lower area absorbs ultraviolet light. The reflection of infrared light is weaker. The flower exhibits two clearly separate zones in its patterns. It has a very prominent bull’s-eye pattern.
Lesser Celandine does much more than guide pollinators to its target with ultraviolet patterning. The gloss contains a promise of hidden nectar. Glands at base of the petals secrete a sugary reward of nectar. However, the substance is not sensed from a distance. The flower has the capacity to angle its petals to flash, or advertise, its presence to pollinators passing overhead.
Petals for Warmth
The flower can also close its petals at dusk as temperatures drop or in intemperate conditions. Researchers have shown that the temperature inside angled petals is warmer than the ambient temperature. This capacity protects seed development.
The Lesser Celandine is not just a beautiful, yellow springtime flower, it is more intelligent than human eyes appreciate.
Gallery of Images
References and Further Reading
- Bond, W. & Davies, G. & Turner, R. (2007): The biology and non-chemical control of Lesser Celandine (Ranunculus ficaria L.) HDRA. Gardenorganic.org. November 2007.
- Lunau, K., Ren, ZX., Fan, XQ. et al. (2020): Nectar mimicry: a new phenomenon. Nature. Scientific Reports 10, 7039. 27 April 2020.
- Parkin, John (1928): The Glossy Petal of Ranunculus. Annals of Botany, Volume os-42, Issue 3, July 1928, Pages 739–755.
- Rørslett, Bjørn (2006): Flowers in Ultraviolet. Arranged by Plant Family. Naturfotograf.
- Rørslett, Bjørn (2003): Ultraviolet Flowers: Ranunculus ficaria, Ranunculaceae. Naturfotograf. 8 May 2003.
- Shipman, Matt (2011): What Do Bees See? And How Do We Know? NC State University News. 27 July 2011.
- van der Kooi, Casper J. & Elzenga, Theo M. & Dijksterhuis, Jan & Stavenga, Doekele G. (2017): Functional optics of glossy buttercup flowers. Journal of the Royal Society Interface. February 2017: Volume 14, Issue 127: 20160933.
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