Fiddling with Fiddlenecks: Pondering upon Existential Questions in Evolution

Walking around the Bernard Field Station during spring, especially after the rainy winter we had, means we get to see lots of beautiful annuals blooming with colourful flowers. As someone who loves spending time outdoors, these patches of flowering plants with all the pollinators are very heartwarming to see.

For my experimental ecology class, during the first half semester, I was required to go out to the field station every week to observe and journal about the flora and fauna present at the field station. As someone who does research on plant ecophysiology, I am always very fascinated by plants in particular, and so a lot of my observations in my journal were about plants.

One of the plants that particularly caught my attention is Amsinckia menzeii, also known as common fiddleneck, because it has these beautiful, bright yellow flowers, and some of them occasionally can also try to disguise themselves as dragons.

Picture of fiddlenecks looking like dragons[1]

Common fiddleneck is a member of the Borage family of plants, which includes both annual and perennial herbs, often with rough, stiff hairs, with leaves arranged alternately, and flowers are arranged in a helicoid cyme, an array that begins coiled up like a fiddlehead and then uncurls and straightens as the flowers open. These plants that are also native to this ecosystem, and thus support a diverse group of pollinators, which I also noticed as I sat across one time, making a species list and seeing all the different bees and beetles that pollinated these annuals.

 

My journal entry about common fiddleneck and patches of flowering annuals and insects [2]

Specifically, what also sparked my curiosity further was that these flowers were arranged in a spiral-like pattern, which very closely resembles a Fibonacci spiral!! Another plant I observed from this family was Phacelia distans, which also has a spiral in its inflorescence, although not as evident once it is blooming, given its relatively broader flowers compared to fiddleneck. But what is common to both is that the flowers have sequential blooming, where the one farthest away from the tip blooms first and starts fruiting, and the ones close to the tip are still in the budding stage, and the ones in the middle are at peak opening.

.

The Fibonacci Spiral and the Fiddleneck and Phacelia Spirals [3][4][5]

Observing this, I started to think about whether the spiralled flowering patterns had any evolutionary role in these plants. However, I had a hard time finding any papers that documented the role of the inflorescence patterns specifically in fiddleneck and their evolutionary roles. An initial Google search yielded some random social media posts, which, although not very scientifically proven or evidence-backed, provided me with some speculations about possible evolutionary reasons like sequential blooming and effective packing.

One possible hypothesis that came up in my discussion with Prof. Donaldson is that a sequential flowering pattern could help in effective pollination, as on a given stalk, only a few flowers would be blooming. This would make the pollinator go to different plants with blooming flowers, instead of visiting flowers from the same plant in quick succession. Furthermore, another hypothesis I found in the scientific literature is that the spiral arrangement itself, being an instance of the Fibonacci spiral, might be an efficient packing strategy. The idea is that successive organs positioned ~137.5° apart (the "golden angle" derived from the golden ratio) can pack the most flowers onto a stem with minimal overlap, which might be very resource-efficient for the plants. Thinking on these lines, it also made me think whether the flowering pattern needs to have any evolutionary role per se, because putting on my biologist hat, I often try to think about life history traits in terms of a possible evolutionarily adaptive role, but it could very well be a consequence of mere happenstance in the evolution of these plants.

Pondering upon a critique of optimality theory I heard at the biology colloquium talk last week, optimality theory being the broad assumption in evolutionary biology that natural selection drives traits toward maximum fitness, made me wonder whether trying to find evolutionary reasons behind this phenomenon of spirals in flowering patterns might also be one such example of telling just-so stories. Maybe these spirals do not have any role to play in evolution, and the spiral is just a product of the physical properties that yield such a pattern, which is so widely common in nature, and something that we humans can love and admire for its beauty, irrespective of its utility.

I am still not fully sure what the reason is behind these interesting flowering patterns in fiddleneck. For now, given that I saw these beautiful plants commonly around the trails, I will spend the rest of my semester in this class trying to investigate whether plants in the borage family, like fiddleneck and phacelia, grow better closer to trails than farther away, and understand what factors could be playing a role in any such differential spatial distribution.

Photo Credits:

[1] Photo by Aabhas Senapati at the BFS

[2] Photo by Aabhas Senapati from his own field notebook

[3] Public domain image.https://commons.wikimedia.org/wiki/File:Fibonacci_spiral_2019.svg

[4] Photo by Michelle Torres-Grant. https://flic.kr/p/7WAZ5V

[5] Public domain image. https://commons.wikimedia.org/wiki/File:Common_Phacelia_(Phacelia_distans)_(53717995112).jpg