By John Green, Texas Certified Expert Gardener, Orange County
The world’s oldest tree (Methuselah) is more than 4,800 years old and pushing the limits of longevity. The tree is located somewhere in the Inyo National Forest (California’s White mountains). The Forest Service doesn’t provide the tree’s exact location for a reason…ensuring protection against social media hordes who might damage the tree or reckless researchers (Getty image).
The Great Basin Bristlecone Pine (Pinus longaeva) trees are known to be the longest living trees. California’s White mountains host the world’s longest living trees with some believed to be more than 5,000 years old. Trees are an important natural resource providing us with useful materials which are integrated into our everyday lives such as wood for building homes, pulp to make paper products, and yet they offer themselves as homes to multitudes of insects, birds, reptiles and numerous other animals. We harvest fruits and nuts such as oranges, apples, pecans, walnuts, pears, figs, and peaches to name but a few. We have learned to use sap from trees to make syrup and latex. Trees are quite literally environmental ‘powerhouses’ providing us with resources (building blocks) for sustainable living: oxygen, food, and shelter.
Fun Fact: Trees are the oldest living organisms on earth and never die from ‘old’ age.
Trees ‘breathe’ by removing carbon dioxide from the atmosphere then releasing oxygen back into the atmosphere. Conversely, we breathe in oxygen and then expel carbon dioxide; we have a mutually beneficial relationship with all plants, including trees but trees do more for us than give us food and oxygen. A trees’ canopy provides our homes shade from sunlight which reduces interior temperatures by 20 degrees F. This decreases energy consumption to cool our homes during summer months.
Like all plants, growth is cyclic in that most growth occurs during the spring and summer months when sunlight is abundant with lengthy daylight hours. Once autumn approaches and daylight hours grow shorter this provides trees with a signal, an alert to begin preparation for winter. There are two distinct categories of trees, deciduous and evergreen.
Deciduous trees’ leaves will begin to change color from green turning red, orange, gold and then brown, because with less sunlight and water for photosynthesis the green chlorophyll begins to disappear. The leaf colors we see in the autumn have been in the leaves all along, but with so much green chlorophyll, we don’t see the other colors until the chlorophyll is gone. As winter approaches, the tree uses less food it stored during summer and goes into a rest period or enters dormancy. Deciduous trees lose their leaves in fall. During extended dry intervals or in times of drought, they will shed leaves during the summer to conserve energy. Oak and Maple trees are both examples of deciduous trees.
Evergreen trees don’t lose leaves (needles) at the same time, they always maintain their branches with leaves which always seem to appear full. They lose a few leaves daily with replacements seeming to be immediate. A pine tree is an example of an evergreen tree which remains green throughout the year. The tallest tree in the world is a Giant Redwood tree located in California which is more than 370 feet tall!
Tree Structure
The structure of a tree is composed of 5 main parts: roots, crown, leaves, branches and trunk.
Roots- much of the tree root system is located below ground, and trees have an immense root system where the number of roots is similar in size to the area above ground. It takes a staggering number of roots to hold upright a 50-foot tree. The root system has three distinct jobs to perform: maintain the upright integrity, acquire water and nutrients from the soil, and store water and nutrients (carbohydrates) for future use.
Crown- a treetop is known as the crown and is made up of leaves and branches. These are the leaves collecting energy from the sun through a process called photosynthesis. It allows the tree to remove excess water (transpiration) to keep it cool quite like us (perspiring).
Leaves- capture photon energy from the sun convert it into sugar (carbohydrates) which is food for the tree. Leaves are micro-food factories that contain chlorophyll and gives leaves their green color. This is an important step in photosynthesis since leaves use the sun’s energy to convert carbon dioxide from our atmosphere and water from the soil into sugar and oxygen. Sugar is stored in the tree’s branches, trunks and roots and oxygen is released back into the atmosphere.
Branches- provide support to distribute the leaves efficiently. They serve as conduits for nutrients, water, and storage of extra sugar.
Trunk- provides the structural support which holds the branches and crown upright. The trunk (is a ‘living’ highway) which transports water and nutrients to and from the soil and sugar from the leaves. The trunk has 5 components: bark, cambium, sapwood, heartwood and pith.
- Bark is the outer layer of the tree, branches and twigs and is a protective layer covering the delicate inner layers. The bark is made up of two layers (inner and outer) with the outer layer being dead cells. The main job of the inner layer of bark is to carry fluid (sap) that is made from sugar, from the leaves to the rest of the tree.
- The Cambium is a thin layer of living cells just inside the bark that makes new cells each year allowing the tree to grow wider.
- Xylem (sapwood) is a living network of cells bringing water and nutrients up from the roots to the branches, twigs and leaves. It is the newest (youngest) wood of the tree. Over time the inner layers die and become heartwood.
- Heartwood is the dead sapwood that is in the center of a tree trunk. It is the hardest wood of a tree giving it support and strength. It is usually darker in color than sapwood.
- Pith is the tiny dark spot of spongy living cells right in the center of the tree trunk. Essential nutrients are carried up through the pith. Being in the center of the tree it is protected from insects and damage by wind or animals.
Fun Fact: Trees can communicate and defend themselves against attacking insects by sending each other signals!
So long for now fellow gardeners! Let’s go out and grow ourselves a greener, more sustainable world, one plant at a time! Please continue sending gardening questions to: jongreene57@gmail.com.
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