Plant growth is such that plants always strive to maximize the amount of sunlight, their energy source, that is hitting their leaves at all times. Due to the often dense growing of many types of plants, it is a constant battle between them to either grow higher to overshadow the rest or seek other methods to use up the remaining light as efficiently as possible.
What hasn’t been as clear is what rules different plants follow when they grow toward the light. Do they have different systems when another plant puts them in shadow? Do different species follow completely separate patterns of growth? These are the questions and we do already know quite a bit about them.
A Full Scan
Researchers at the Salk Institute, however, wanted to create the clearest picture ever derived of how plants grow from seedlings up to their adult forms over time. Knowledge of this process and any disparities between plants could help determine, such as with agriculture, which crops are more suited for which types of particular growing scenarios. Or which crops would do better growing together with certain other crops.
They selected sorghum, tobacco, and tomatoes as three crops important in agriculture and science and set up a trove of seedlings from each. Then, they used high precision 3D scanning technology to measure their exact shape every few days as they grew. The scanners converted the image of the plants into what is called a point cloud, where every spot of the plant is assigned a point with a number value to show exactly where it is in the space.
Assigning number locations is one of the important parts, because it allows the numbers to be run computationally in order to compare how they change over time, creating a mathematical model of how different plants grow. This sort of technology, while envisioned as early as the mid 80’s, has really only come into its own over the past decade with increasing computer complexity allowing full 3D maps to be created.
In total, they scanned 557 plants from the three target species, which had also been grown in 3-5 different types of environments in order to see whether that changes how they grow. They were scanned twenty to thirty times over their run toward adulthood. What the scientists discovered can be summarized into three specific insights into plant growth.
The first property they observed is called “separability”. It refers to how each leaved branch grows independently of the others. The speed of growth is not dependent or related to any of the other branches. It is a basic system that allows the plant to nonetheless still grow equally in whichever direction it needs to.
The second and perhaps most apparent trait is called “self-similarity”. All it means is that, even if the plants grow in different directions due to different light sources and their branches grow independently of each other into different shapes, the overall basic shape of the plant will remain the same and be the same as all the other plants as well. No matter how much it stretches in one direction or densely bushes together, the actual structure of the base plant is the same.
The last mechanism isn’t so much a capability as an observation. The growth of the branches of a plant and how much they cluster is based on a bell curve. The branches near the base are the most dense and their density farther out falls off perfectly following the expected mathematical bell curve.This likely is related to maintaining structural integrity of the plant, where too dense of a leading branch would make it prone to breaking or make it inadequate for transferring energy, water, and other compounds back to the main trunk or out to the branch.
Growing Impossible Plants
These three properties are maintained under all environmental conditions, no matter if in flood or drought, whether in full sunlight or in shadow. This functionality is also highly efficient and is the sort of method that would be expected from natural selection leading to the most basic option that nonetheless works well enough.
Better understanding of these properties may help contribute to research in genetically modifying crops and being able to manipulate the genes for them, allowing things like densely built branches. Since human farmers are far more capable of sustaining a plant grown in such a manner than the plant could if living in the wild. This may allow for new growing capabilities where modified crops will have long branches with dense amounts of produced fruit that humans help to hold up so they don’t break off. But that’s just an imagined thought on my part.
The Basic Math of Nature
The other more directly interesting revelation of these properties relates to the title of this article, which i’m sure the reader was wondering if it would come up at all. These three mechanisms, separability, self-similarity, and the branch density bell curve, are exactly true for brain neurons too, especially in regards to the dendrite offshoots they form.
It seems that it is not just a funny coincidence that the process of growing new dendrites is referred to as dendritic arborization or dendritic branching. A cluster of dendrites is also referred to as dendritic trees. These terms were clearly originally made just for visual similarities between the two, but now it appears that there is more than just a visual relationship.
The mathematical and evolutionary mechanisms that make up how branching structures grow is likely identical between the two. This isn’t that surprising of a find and it does not mean there is anything more connected between plants and brain neurons. They are not the same thing. It is just that the math-based logic possibly inherent to the universe or at least in the evolution of life went for the simple path with both and that path for growing branched structures is the same.
It is an interesting quirk to ponder. No more than that, but it does show that basic mathematical laws are ubiquitous, much like how the Fibonacci spiral can be found throughout nature as well. And it’s certainly something new for philosophers to think about.
Photo CCs: Nicotiana tabacum 002 from Wikimedia Commons