By Tim Clancy, for Let’s Talk Plants! July 2024.
One of the trees in the author's “neighborwoods” is an Aleppo pine, Pinus halepensis. Photo credit: Tim Clancy. November 2023, “Looking fine.”
The Case of the Leaning Tree
As a person who genuinely admires trees it will come as no surprise that certain trees are favorites for a multitude of reasons. Maybe it’s the biggest one of its species that I have seen. Or perhaps it blooms so proliferous as to be worthy of all-star status.
Then we have the internal workings of trees. How they move water and nutrients to the various locations needed for successful growth, survival and perpetuation of the species. Included in the internal workings of the plant are all the necessary components for the tree to stand-up and capture sunlight for photosynthesis. How trees stand up is studied in the discipline known as “Biomechanics”.
One of the trees in my “neighborwoods” is an Aleppo pine, Pinus halepensis. The tree was named the Aleppo pine in the 1768 book “The Gardener’s Dictionary” by famed 18th century botanist Phillip Miller. It is believed he never went to Aleppo and named the tree after a visit to gardens under the care of the Duke of Richmond where he saw large specimens.
There is a large Aleppo pine not too far from my house. I have been looking at this tree for more than the 35 years I have lived on the street. It has been spared the all too familiar situation of over-pruning. It is about 30’ tall and has a canopy spread of maybe the same. Both of these attributes are unremarkable. One might question its height after 35 years and this can be attributed to the growing conditions of mostly low water availability. It is right at the edge of a lawn at an apartment building and the turf uses whatever water the owner is willing to pay for. However, the fact that the tree is less than a mile from the ocean bodes well as opposed to being inland where water demands are significantly more.
The remarkable characteristic about this tree is its decidedly odd growth habit. Instead of growing relatively straight the tree decided to bend about six feet above grade and now resembles a sort of S shape.
This is where the biomechanics come in. As you can see in the photos the tree has somehow managed to attain a fairly decent size while looking like it may tumble over any minute.
If you look closely, you can see areas in the trunks where there is more “wood”. There is a particularly large bulge on the apartment side of the tree. This is the tree’s response to the stress of leaning. Trees have the ability to sense the stress and can create support wood where it’s needed. This can be easily observed in all sorts of trees throughout the county. I have been very fortunate to have had the opportunity to watch this tree for the last 35 years.
Unfortunately, that time is coming to an end. The tree has been in decline for the last few months. And is not long for this world. It appears to have been infected by a fungal disease. Its decline has been a headscratcher for me because, by all outward appearances, nothing has changed relative to the tree’s environment. The other interesting thing about the situation is the speed with which it is declining.
I am saddened that the end of its story is so fast approaching as I was hoping to observe the tree adjust and respond to the growth stresses of everyday gravity. It has been a great teacher and fine example of how tree biomechanics work.
There is a great explanation (perhaps obtuse to those of us not biology majors) of plant biomechanics by Dr. Karl Niklas named aptly “Plant Biomechanics”. Happy Reading!
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