We love our gardens for their beauty, color and scent. We love seeing the movement that passing breezes create and the hoar frost shining on bare branches in winter. Maybe our gardens provide food for our family and friends. And for sure, our gardens nurture our spirit and exercise our bodies. But behind all that beauty there are hard sciences at work. And yet, the nearest we get to thinking in scientific terms is the NPK (nitrogen/phosphorus/potassium) information on a bag of fertilizer.
Now, my chemistry and physics education is minimal, and my math is not much better, so I struggle sometimes to understand the more scientific explanations and explorations that are going on in modern horticultural (and other) research. Still I’d like to share with you some of the fascinating ideas I’ve come across.
Origami
The Japanese art (or, science?) of paper-folding is more than a fun party trick. We can learn to make a paper airplane, a bird, a star, a frog. But did you know that origami exists in the natural world?
Think of a how a ladybug’s wings unfold from below her bright red outer “wings” when she takes off into the air. Her flight wings are much bigger than her outer protective wings, so they need to be folded away when not in use. See it here https://www.youtube.com/watch?v=P335P-LtA10.
A butterfly’s wings si
milarly are folded tight inside the chrysalis and must be unfolded as it emerges before it can fly. See it here https://www.youtube.com/watch?v=R5QH3bGF4uU.
The buds of a beech tree are long, slim and pointed – a little like a furled umbrella. Yet they contain a full-size beech leaf. When the bud opens, the leaf which is tightly folded, gradually opens out by unfolding. See it here https://www.youtube.com/watch?v=2nUi-kmr-8k
Even our brains are folded to provide a much bigger surface area than our skulls could contain if the brain had a simple smooth surface. Folds not only enable large surface areas to be contained in small spaces but can also produce extremely strong structures.
Using mathematics and computer programs, scientists are studying the complex folding techniques that occur in nature to produce everything from huge light weight aeroplane wings and solar arrays for use in space to creating to tiny robots and medical implants, e.g. arterial stents, which unfold once injected into the body.
For more on this watch the PBS Nova program, ‘The Origami Revolution’ here http://www.pbs.org/video/2365955827/
Fibonacci (fib-on-arch-ee)
Fibonacci was an Italian mathematician who lived in the 12th century. He identified the mathematical sequence of numbers where the following number is always the sum of the preceding two numbers:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144 and on and on
This sequence or pattern is found all over the place in the natural world. It exists in the number of petals on a flower, the number of seeds on a plant, the arrangement of a plant’s branches and leaves as well as in the shape of a nautilus shell and a hurricane.
Examples of Fibonacci petal arrangements include Lily and Iris (3), hardy Geranium (Cranesbill), Columbine (5), Delphinium (8), Cineraria, Ragwort (13), Chicory, Shasta daisy (21), Plantain, Pyrethrum (34), Asteraceae family (55, 89).
That is not say that all flowers have petals that follow the Fibonacci sequence. For example, there are many flowers with four petals. Wallflowers and Evening Primrose are just two.
Pine cones are arranged in two spirals which conform to the Fibonacci sequence. The seeds of a sunflower are arranged in a complex ‘Golden Spiral’ to pack the maximum possible number of seeds onto the seed head.
It is thought that the precise arrangement of petals, leaves and seeds enables plants to obtain the optimum in terms of available sunlight and rainwater and the maximum seed production.
The shell and the hurricane conform to the ‘Golden Spiral’ which is based on the ‘Golden Ratio’ which is based on the Fibonacci sequence. For more on these, go to https://en.wikipedia.org/wiki/Fibonacci_number
Of course, you can argue that we see the sequence in nature because we look for it. That is, it’s not an immutable “law of nature” which was just waiting there for a mathematician to spot. Either way, it is interesting.
For a more detailed look at mathematics in nature, go here http://www.pbs.org/wgbh/nova/physics/describing-nature-math.html
Chemistry as communication
Research taking place all over the world is revealing that plants and their relationships with the surrounding environment are much more complex that had been realized.
Mychorrizae (soil fungi) in the soil combine with plant roots and create pathways between separate plants. These pathways allow the exchange of moisture and chemicals between plants and the mychorrizae. Plants stressed by drought will communicate that with other surrounding plants prompting those other, as yet un-stressed, plants to close their leaf stomata, reducing transpiration and so conserving water.
Plants can also communicate through the air, by way of air-borne VOCs (volatile organic compounds). Experiments have shown that beans give off VOCs when attacked by aphids. The VOCs prompt nearby bean plants to give off different VOCs that attract aphid-eating wasps and repel the aphids.
Mature trees “help” seedlings and saplings by providing them with extra carbon through the mychorrizal network. The suggestion is that these young trees might not survive otherwise on the shaded forest floor.
It is known that some plants use allelopaths to inhibit growth of nearby plants thus reducing competition for light, water and nutrients. Examples include Acacia, Ailanthus altissima (tree of heaven) and Juglans nigra (black walnut).
See more here http://www.the-scientist.com/?articles.view/articleNo/38727/title/Plant-Talk/ and here http://www.bbc.com/earth/story/20141111-plants-have-a-hidden-internet
Apologies to the scientists and mathematicians among you for my low level take on all this. I just think it is fascinating to see these features and connections in our natural world. Many of them are things we can identify in our own back yards if we just look a little more closely. Many of them occur too in the vastness of outer space (and beyond?). Unseen connections in the atmosphere and underground are shaping the way our world develops and grows as well as our own back yard spaces.
Anne Hughes
A Denver County Master Gardener
All photos courtesy of http://www.pixabay.com, a source of royalty free images.
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