Tree Ring Patterns
Date: Summer 2013
So we cut down a tree and it had a very unusual pattern. It looks almost like a map. It has very dark brown and black lines that kind of squiggle all across the stump making it look like a map, or like countries. I was wondering if this was unusual because we couldn't find anything about it on other websites?
Thanks for the question. There could be several explanations for your observations. Sometimes tree rings grow asymmetrically and are not perfect circles. Perhaps there was an infection in the tree during its growth period?
I hope this helps. Please let me know if you have more questions.
Tree ring growth can be compromised from a symmetrical, circular pattern for a number of reasons. The rings represent the growth of the xylem and phloem (water and food transport tubes) by the cambian (growth)layer of the tree and normally it will produce rings of different thicknesses, depending upon the season of the growth. That said, different species of plants will grow in different ways and some plant species are not symmetrical in this growth at all. Disease, injury to the trunk or stress from internal or external factors, the growing of a limb outward from the center of the plant, climate irregularities, and other factors may cause the growth of the cambian to not be uniform. I would find the species of plant you are examining and search the web on its characteristics.
Either the tree rings are showing you the differential patterns of growth (for example, the sunny vs. shaded sides of the tree branching of the main trunk) and/or especially the black lines might be telling you something about fungus infections of the tree/wood.
Harvard University Herbaria
Unfortunately its pretty hard to tell what caused the pattern without knowing what kind of tree, where it grew, and seeing the pattern. Many things can cause different patterns: old damage, fire scars, fungus, insects, odd growth patterns due to past conditions, and more. Each species of tree has its own particular patterns as well, some fairly distinctive.
I suggest taking a picture to show to an arborist or naturalist in your area. Good luck.
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