While I was gardening

The art of gardening and the science of life.

The Evolution of a Garden, Part II; apologies to Charles Darwin

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“. . .  from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.”  Charles Darwin

I’ve gardened for many years.  I’ve made countless mistakes and had a few successes, encountered occurrences that I can’t explain and a few I figured out, and have witnessed a couple of genuine surprises.  But the one aspect of the plant world that intrigues and impresses me more than all others is the seemingly endless forms and shapes that plants have evolved over time.  Cactus and other succulents; mosses and ferns; grasses and reeds; the flowers of orchids; ball, vase, or pear-shaped plants; and the wide variety in color, shape, and size of trees. I see many gorgeous new plants at nurseries in colors, shapes, and/or sizes foreign to that particular species but I am always keenly aware that no hybrid can match what nature produces.  The determined, contorted shape of a bristlecone Pine (Pinus longaeva) struggling to survive on a rocky, wind-beaten mountain side is a sight that words are inadequate to describe.  No hybrid compares to the broad expanse of an ancient southern live oak (Quercus virginiana) spreading its limbs to the world.   And I have never seen flowers more exceptionally compelling than those of the Tacca genus.  One look at Tacca chantrieri, Black Bat Flower, is all you need to remember the flower for the rest of your life.

These examples came to mind while I was working around one of my beloved conifers, Thujopsis dolabrata, Elk Horn or Hiba Cedar (not a true cedar).  (Due to lack of space, I grow the dwarf form of the tree.)  The unusual shape that this trees’ foliage has developed over time intrigued me from my first viewing, and continues to be a source of interest to me. This little tree adds exceptional beauty and interesting form to my garden more than any other plant I grow (pictured below).

Its two most attractive features are its broad, flattened branches and the bright, white underside of its foliage.  What in the trees’ environment caused this flattened foliage?  Did a very specific animal group utilize it and help create the development of its peculiar form?  Did a disruption in the availability of water occur in its native environment at some point – cool, moist forests of Japan – that prompted a mutation of flatter, wider foliage and more conspicuous stomata than neighboring conifers?  Did this change allow the tree to absorb more moisture from the surrounding air during times of drought?  Or did this mutation allow it to transpire excess moisture during times of soil saturation?  Possibly a response to extremes in temperature, or a response to excessive shade at some point?  Because the tree is not drought tolerant, a likely explanation is a response to water need, but the question still remains.

This tree is unique also in that it is the only species in its genus, not a common occurrence in the plant kingdom.

What origins do these shapes, colors, and sizes have?  We are taught that a mutation in the DNA of a plant brought about a change in that plant that enabled it to survive and reproduce a bit better than previous members of its species, therefore enabling it to out-compete its neighbors in acquiring nutrients and in reproduction.   In Part I of this series (post from November 2014), I make the statement; “The mysterious process of evolution, the driving force behind life, must itself be driven by something we have not yet discovered.”  That plants respond to the surrounding environment is a fact; but why they respond in a specific manner (as opposed to some other response) and at what level this response affects their survival and ability to reproduce is a mystery.

I agree with Mr. Darwin; the endless forms that occur in nature among plants and animals are beautiful and wonderful.  And a far greater gift than we often recognize.

Thujopsis_dolabrata_Nana_Variegata_0294_originalThujopsis_dolabrata_Nana_Variegata_0306_original

Pictures by Plumb Pixel Photography, Terri Johnson, Owner

PlumbPixelPhotography.com

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Author: dphare2014

Horticulturist, Lead Steward Carkeek Park Demonstration Gardens, Author

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