Like all other organisms, trees grow and change over time. The tiny seedling you plant today will turn into a lush, vibrant sapling within a year or two. In a few decades, the tree will be fully grown, and in a hundred years, it will be a huge monster that reaches high into the sky.
But this growth and development doesn’t happen in a haphazard fashion. In fact, trees grow in very specific ways. One interesting thing this means is that tree branches don’t grow up with the tree as it does. A branch will always be the same height it was when it first came out of the trunk as a bud.
Plants grow in fascinating ways that allow them to adapt and thrive in various environments. Understanding the basics of plant growth can help gardeners better care for their plants. In this article we will explore how plants grow and the key factors that influence their growth patterns.
Meristems – The Growth Zones
Plants grow from specialized tissues called meristems located in the tips of roots and stems. Meristems contain rapidly dividing cells that enable new tissue formation and growth. There are two main types of meristems:
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Apical meristems – located at the tips of stems and roots, They facilitate upward vertical growth in plants
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Lateral meristems – located around the vascular tissues in stems and roots They are responsible for thickening of plants.
As meristematic cells divide, some daughter cells expand while others remain as new meristem cells. This allows plants to continuously generate new cells for growth while maintaining their meristems.
Directional Growth Patterns
Most plants exhibit upward apical growth from their shoot tips and lateral outward growth from their roots. However, growth patterns can vary between plant groups.
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Dicots like trees and most flowering plants grow upward from their shoot tip meristems. Their roots extend outwards from the root tip meristems.
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Monocots like grasses and palms often exhibit basal growth. Their meristems are located at the base near the soil. New leaves emerge from the base while roots grow downwards into the soil.
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Vining plants like ivy exhibit downward growth. Their stems grow downwards with specialized root-like holdfasts to attach to surfaces.
These varied growth patterns allow plants to maximize light exposure and nutrient absorption in their distinct environments.
Influencing Factors
While meristematic activity drives plant growth, various external factors can impact growth rates and patterns.
Light
Plants grow towards light sources, a process called phototropism. Light stimulates auxin distribution, causing elongated cell growth on the shaded side so stems curve towards light. Plants also adjust their form based on light availability.
Gravity
The influence of gravity on plant growth is called gravitropism. Roots grow downwards while shoots grow upwards against gravity. This effect is also mediated by auxins.
Temperature
Warmer temperatures accelerate cellular activity and growth up to an optimal point. Extreme cold or heat will stunt plant growth.
Water
Water availability directly impacts cell turgor pressure which drives expansion and growth. Drought conditions will suppress growth.
Nutrients
Adequate nutrition provides the building blocks for growth. Lack of important elements like nitrogen, phosphorus and potassium slows growth.
Pruning and Damage
Pruning stimulates dormant meristems and nutrients are redirected to new growth. However, severe damage to meristems can permanently impair growth.
Optimizing Plant Growth
Understanding where and how plants grow allows us to optimize our gardening practices for healthier plants. Here are some tips:
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Ensure young transplants are planted at the same level they were growing to avoid burying stem tips.
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Prune just above leaf nodes to preserve apical dominance instead of blunt cutting which removes the meristem.
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Provide optimal sunlight exposure, moisture and nutrition to fuel growth of both roots and shoots.
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Monitor for pests that may damage soft growth tips.
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Allow lawns to grow taller before mowing to preserve growing points and limit stress.
With proper care centered around their meristems, plants can achieve their full genetic growth potential in our gardens. Exploring plant growth patterns continues to fascinate botanists and gardeners alike!
They May Not Move, But They May Disappear
If tree branches don’t grow higher as the tree does, that doesn’t mean they will stay that way. As trees grow, many of them lose their lowest branches.
This can occur for a number of different reasons. It’s likely that the oldest parts of the tree are at the bottom. This means that the lowest branches have been exposed to weather, pests, and diseases for the longest time. As a result, they’ll probably start to rot first. When the decay on the branch gets bad enough, the limb is shed to keep the decay from spreading to the trunk.
Trees may also shed their lower limbs in response to a reduction in sun exposure. As trees get taller, the top branches start to block a lot of the sunlight that used to reach the lower branches. Unable to maintain photosynthesis, the limb slowly dies and is shed by the tree.
How Do Trees Grow?
Before we look at how trees grow, let’s look at how grass grows to help make the point.
Grass blades grow from the bottom, near the ground. In other words, cutting the tops off of the blades with a lawnmower won’t hurt the biologically important parts of the blades. Over the next week or two, the blades will get a little longer, but if you look closely, you’ll see that the tops of the blades haven’t changed or grown at all. They’ll still have the mower’s blade marks on them.
Trees grow in the opposite fashion; they grow from the top. Specialized cells in the ends of each tree shoot (including the primary leader) form areas called meristems. These meristems are the locations from which a tree grows taller and limbs grow longer. Cut a tree like you cut grass, and the meristems would be gone. The tree would no longer be able to grow taller or longer.
However, trees grow from their very ends, which means that the branches that come out of the trunk will never get higher. If a branch grows 3 meters off the ground, it will still be 3 meters off the ground the next year.
Trees have another kind of meristem that lives under the bark and wraps around the trunk and branches. These meristems are responsible for lateral growth (they allow the trunk and branches to increase in diameter).
Topping & Trimming Plants in Early Veg Stage
FAQ
Do trees grow from the bottom or the top?
Do plants grow from the root or end?
Which part of a plant grows first?
Do roots grow from the tip or the base?