Why Do Some Trees Grow in Spirals?

Spiral grain in an lodgepole pineI noticed a funny thing out in the woods the other day. I came across a fallen log, its bark long stripped away by the gleaning of industrious birds and mammals. The exposed wood, rather than running in straight furrows from end to end, spiraled around the trunk, helix upon helix from end to end. I was mystified.

If the shortest distance between two points is a straight line, and trees in a forest are under intense competitive pressure to reach the canopy as quickly as possible, why would a tree ever spend precious energy and resources growing in circles? What could possibly make a tree behave so strangely?

As with many natural phenomena, a lack of a definitive explanation provides fertile ground for speculation, and theories abound as to why some trees take on this curious growth form.

A couple of likely reasons:

Spiral growth is beloved by photographers for the beautiful curves to be found in the bark and wood of the trees. Sawmills, on the other hand, are not so pleased to see a spiral-grained log in their yard; the wood is often weaker and spiral-grained boards often twist as they dry. Despite the reduction in the raw strength of the wood itself, spiral growth gives a tree greater flexibility than its straight-grained neighbors, making the tree more resistant to high winds or heavy snow loads.

Another possible cause for spiral grain is to better distribute water around the tree. In straight-grained trees, the needles (or leaves, though spiral growth is more common in conifers) share water, photosynthate, and nutrients with the roots directly below them. If the roots or branches were to be damaged on one side of a straight-grained tree, the corresponding roots and branches would wither.

A spiral grain, on the other hand, allows resource sharing all around the tree, distributing water from a single root to branches all around the tree, and sugars made in the leaves on a single branch to all the roots. By distributing water and nutrients evenly, a spiral-grained tree can more easily survive periods of drought or windstorms, as well as the chronic stresses of growing in dry, windy areas.

Unsurprisingly, spiral grained-trees are often found on dry ridgetops where the twin forces of exposure and desiccation are at their greatest. Bristlecone pine in particular, famous both for its longevity and for its habitat high on the windswept Sierras, often exhibits spiral growth.

A few other theories involve genetics, heliotropism (tracking the sun), the Coriolis effect (which causes the clockwise pattern of winds and ocean currents in the northern hemisphere, and mechanical torque from prevailing winds. What do you think?

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About the author

Richard joined the League’s staff in 2012 as the Conservation Science Manager and now serves as Director of Restoration. He brings nearly a decade of experience in forest management and restoration.

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16 Responses to “Why Do Some Trees Grow in Spirals?”

  1. Yoav Bar-Ness

    For what it’s worth, here in Tasmania at 43 degrees latitude south, we have ancient giant eucalyptus tree rotating in both directions, in many wind and light environments. I do not think it is solar or Coriolis effects.

    Reply
  2. Roger

    It’s exciting to meet some fellow observers of handedness. I too noticed that when trees or vines spiral it is almost exclusively to the right from the ground up or germination point. This is also true of the whorls of sea shells, the DNA helix, amino acids, the right hand rule in electronics, the eyes of the
    Trade Winds whether in be in the Northern or Southern Hemisphere. Most everything on earth loves from left to right. The water goes down the drain in the same direction regardless of where on earth you are. The earth itself is the prime example of movement left to right left to right. The sun rises in the East whether in Alaska or Australia. I discovered early on that the confusion over right and left handedness lies mostly in our point of view. Looking up at any rotating object it appears to go in one direction while looking down on it, it appears to be going in the opposite. After questioning the reason for right handedness for a number of years I have come too believe there must be a metaphysical reason for it and it’s true of the universe. Even the Sign of The Cross is from left to right. I wish so to understand it. Thanks for your site Richard. See you in the deep woods.

    Reply
  3. Chaz Stevens

    All amino-acids have a right hand twist.

    Reply
  4. BEVERLY MITCHELL

    I saw a tree in Florida that was both the trunk and all the branches were swirling to the right. It was beautiful. I do not know if this is the way that particular tree species grows or what. Any ideas?

    Reply
  5. Colin Eldridge

    This page has a TON of primary sources on the subject of the reason between spiral grain in trees:
    https://link.springer.com/article/10.1007/BF00204333

    Reply
    • Dr Anne Silk

      Are you the same Colin Eldridge who was SMC Clerk in London when I was Master? If so we are both working on helical energy . Mine is in humans as microtubules also have helical energy from unpaired electrons. If it is you , warmest good wishes Anne

      Reply
  6. Lance

    The Coriolis effect really only affects large systems and isn’t strong enough to affect something as small as a tree. Just play with a drain sometime, you can get the whirlpool to go both ways. Additionally I’d argue that trees can change their growth pattern throughout their lives. It probably has more to do with unbalanced nutrient absorption via roots in poor soil and extreme wind/weather stressing the tree. This page does a pretty good job of quickly summarizing some of the research that has been done. If anyone knows of actual primary source material that would be great. https://www.conifers.org/topics/spiral_grain.php

    Reply
    • peter van sommers

      the reason that tree bark spirals consistently in one direction in the southern hemisphere and the opposite in the north arises from the direction of the sun’s apparent movement in the two hemispheres. Since each day the light falling on the tree throughout its growth swings from right to left or left to right and the plant , following the sun to gain maximum exposure twists one way or the other. At first I thought it was something about the species of tree since I first noticed it in a grove of similar tree species near our home showing the one effect while nearby a few trees of a different type grew straight. However as time passed I saw that dozens of species all going in the same direction here in Australia and there were absolutely zero growing as northern hemisphere trees do. So, unless someone else has dropped onto this mechanism, let’s call it the “vanS” effect to do honour to this 88 year-old nature lover.
      Peter van Sommers (vanS!)
      Background: neuropsychologist, Harvard PhD, Visiting Scientist at Cambridge, Oxford, the Sorbonne and elsewhere and now a painter, printer, photographer and garden-lover.

      Reply
      • Darryl Phillips

        I thought so too, except that the spiral is the wrong way. Look for yourself. If the tree spiraled towards the sun it would twist to the left as viewed from the ground. But they twist to the right in the northern hemisphere, at least here in the US. They twist opposite to following the sun. Or the moon /snark

        Reply
    • John lenz

      The reason a Madrone tree grows in spirals helix’s is because of a vine that wraps around them and constricts as they grow around the vine to give it that spiral look.

      Reply
      • Jeremy

        I like this theory. Ive seen younger trees, 4-8 year olds maybe, with old vines spiraling around the trunk as they reach for the sunlight above the canopy. Also seen trunks, after the vines are dead and gone, with spiraled scar impressions, where a vine once grew.

        Reply
  7. Jayashree

    The coriolis effect seems to be the most probable answer. The best way to test it would be to see if all these trees twist in one way in one hemisphere, and the opposite way in the other hemisphere, preferably far from the equator .
    If any one does indeed check this out, pl post it here for all to know

    Reply
  8. Tom Adams

    I think the spiral growth in cedars(etc) is to convert oscillatory(linear) movement to rotational movement. In a shallow rooted tree, this would help to prevent wind induced toppling. Let me know what you think of this theory. Spiral growth would decrease linear growth(height) and therefore put the tree at a seeming disadvantage. There must be a powerful advantage in spiral growth to overcome this. Let me know what you think of this hypothesis.

    Reply
    • Peter Ruby

      Tom, it is obvious that if trees are twisting one way on the northern and the other on the southern hemisphere that the direction of the twist has something tódówith Coriolis forces. But the direction does not equal reason. The reason I believe might be the one you propose – i.e. advantage in growing in a spiral manner on specific locations.
      But nobody as yet confirmed a genetic twist – what if occasionally there is a DNA mutation which makes the tree to grow this way? That could be proven by collecting a twisted tree seeds and watching if the seedlings all also grow twisted.

      Reply
  9. Antony Branfoot

    Heliotropism seemed likely when most trees I have seen here spiral up and to the right but I have seen the reverse on a few and wondered if they came from the southern hemisphere but did not identify which they were. If it were true that there is a reversal across the Equator, we might have solid evidence for phototropism.

    Reply
  10. Luke

    I enjoy the variety of redwood tree growth habits. Most grow very straight, but I’ve seen many spiraling redwoods. The rarest grain is the wavy grain.

    Reply

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