While I was gardening

The art of gardening and the science of life.

Symmetry

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The symmetry of a flower makes visual sense.  Symmetry is not just elegant and attractive; we perceive it as evidence of health, strength, and normality.  Most flowers have radial symmetry (think spokes of a wheel).  Another form of symmetry is bilateral, where if the flower is divided down the center the two sides look identical.

Camellias, dahlias, echeverias, and flowers in the Asteraceae family are among the many plants whose flowers have radial symmetry.  Pansies, orchids, snapdragons are a few of those flowers with bilateral symmetry.  Radial symmetry is so common in the plant kingdom that we often perceive a flower as having this pattern when in fact it does not.

One of my late spring chores is to plant the many containers I have around the property.   This is one of those infrequent garden projects that calls for creativity over chore and enjoyment over effort – mostly because it calls for multiple trips to my favorite nursery!   Not being a shopper gifted with patience, a nursery is the one store I visit where I don’t have to fight the urge to leave within 10 minutes of arriving.   So a warm, clear spring day called me forth and shopping I went.

Rows of blooming plants or colorful foliage for pots and hanging baskets complicated my choices for the many containers that needed filling.   I’m inclined towards annuals with colorful and/or unique foliage for most of my containers – less maintenance during summer and longer display time – but one flowering plant caught my attention.  The color of the bloom was hot crayon pink and its shape almost perfectly round; the leaves lanceolate; stems and foliage covered with fuzz.   ‘This is a ridiculous looking plant’, I thought to myself as I bought it.  ‘I don’t even like the color.’

I planted the Gomphrena in a pot alone and placed it on the front porch where it would receive full western sun and the reflected heat from concrete steps, and it bloomed continuously through summer.  An interesting effect was created as the blooms aged; small gold spots develop at the tips of the petals – a nice sparkle especially at sunset.    But as the color of the blooms was not my favorite and the plant required so little care, I didn’t pay much attention to it until my spouse (a scientist to his core) noticed that the blooms offered something out of the ordinary.  At first look, the flowers appear to have common radial symmetry.  But looking closer, we noticed the petals are arranged in a spiral pattern –   perfectly symmetrical, but spiral rather than radial.   Spiral symmetry seems not as common in flowers as bilateral or radial, but it does seem to be more common in leaf arrangement.   Some succulents have spiral arrangement, as do some vegetables.  The gorgeous, flavorful Romanesco broccoli is spiral; fractal spiral, to be specific.

Does spiral symmetry offer a plant an advantage over radial growth pattern?   Better ease of seed dispersal?  Quicker, more efficient pollination?  Neither seems likely.   A random mutation that proved as successful as radial symmetry, but no more so?  Does it just narrow down to the prevalence of self-similarity in nature?   Spiral patterns exist in all parts of the natural world – creatures in the oceans, the plant world, animal world, and many galaxies.  Or is it just that I haven’t been as observant as I should, haven’t looked as closely as I should to each bloom?  Spiral symmetry – this is one of the many small mysteries of the plant world that will keep me on alert for years to come.

What more can one ask of a plant?

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Author: dphare2014

Horticulturist, Lead Steward Carkeek Park Demonstration Gardens, Author

One thought on “Symmetry

  1. After reading this post I took a good look at my indoor succulents as they live in my room and are always at hand. I noticed that all the Echevarias that I own display the lovely radial symmetry while the two different Crassulas I own have bilateral symmetry. It is fun to see all the differences in plants and all the beautiful ways nature has devised to surprise us. Love reading your posts. Keep up the excellent work!

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