A Tree Guide - 11 Things You Need to Know about Trees

See Trees as You Never Have

Trees are literally everywhere. A tree is the most obvious and remarkable plant you will see when you venture outside. People are infinitely curious about trees in a forest or a tree in their yard. This tree guide will enable you to satisfy that curiosity and explain a tree in detail.

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How a Tree Grows

tree sapling
A sapling on a stub in a forest. (Alanzon/Wikimedia Commons/CC BY-SA 3.0)

Very little of a tree's volume is actually "living" tissue. Just one percent of a tree is actually alive but you can be assured it is working overtime! The living portion of a growing tree is a thin film of cells just under the bark (called the cambium) plus the leaves and roots. The cambial meristem can be only one to several cells thick and is responsible for Nature's greatest work - the tree.

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Parts of a Tree

diagram of parts of a tree

Trees come in various shapes and sizes but all have the same basic structure. They have a central column called the trunk. The bark-covered trunk supports a framework of branches and twigs called the crown. Branches, in turn, bear an outside covering of leaves - and don't forget the roots.

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Tree Tissue

tree tissue diagram

Tree tissues are a combination or bark tissue, root tissue and vascular tissue. All these tissues made of numerous cell types are unique to the plant kingdom and to trees specifically. To completely understand a tree's anatomy, you must study the tissues that support, protect, feed, and water a tree.

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The Structure of Wood

tree cells
The Cambial Layer. (University of Florida/Landscaping)

Wood is a combination of living, dying and dead cells that function much like a lamp wick, moving liquids up a tree from water-seeking roots. The roots are bathed in a nutrient-rich liquid which transports basic nutrients to the canopy where all is consumed or transpired. Tree cells not only transport water and nutrients to leaves for photosynthesis but also form the entire structure of support for the tree, store usable sugars, and include special reproductive cells that regenerate the living inner and outer bark.

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Where Trees Live

map of common forest types

There are very few places in North America where a tree just can't grow. All but the most adverse sites will not support native and/or introduced trees. The United States Forest Service has defined 20 major forest regions in the United States where certain trees are most often seen by species. Here are those regions.

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Major Tree Species - Conifers and Hardwoods

conifer tree cones
Conifer cone cluster. (Jon Houseman/Wikimedia Commons/CC BY-SA 4.0)

There are two major groups of trees in North America - the conifer tree and the hardwood or broad-leaved tree. Conifers are identified by needle-like or scaley-like leaves. The broadleaf hardwood tree is identified with wide-bladed, broad leaves.

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Identify Your Tree With a Leaf

The leaves on this plant are arranged in pairs opposite one another, with successive pairs at right angles to each other (decussate) along the red stem. Note the developing buds in the axils of these leaves. (Marshman/Wikimedia Commons/CC BY-SA 3.0)

Find a tree in the forest, collect a leaf or needle and answer a few questions. At the end of the question interview you should be able to identify a tree's name at least to the genus level. I am confident you can also select the species with a little research.

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Why a Tree Is Important

girl hugging tree
(Mike Prince/Wikimedia Commons/CC BY 2.0)

Trees are important, valuable and necessary to our very existence. Without trees, we humans would not exist on this beautiful planet. In fact, some claim can be made that our mother's and father's ancestors climbed trees - another debate for another site.

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A Tree and Its Seeds

germinating seeds
Rain tree seeds germinating. (Vinayaraj/Wikimedia Commons/CC BY-SA 3.0)

Most trees use seeds to establish their next generation in the natural world. Seeds are tree embryos that burst into growth when conditions are exact and transfer tree genetic material from one generation to the next. This fascinating chain of events - the formation of seed to dispersal to germination - has fascinated scientists since there were scientists.

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Autumn Tree Color

fall colors
Autumn leaf color around Kuraigahara sansō in in Mount norikura, Matsumoto, Nagano prefecture, Japan. (Alpsdake/Wikimedia Commons/CC BY-SA 4.0)

Autumn turns on a very miraculous switch that colors most trees in broad-leaf forests. Some conifers also like to display color in fall. The fall tree senses conditions that tell it to close shop for the winter and begins to prepare for cold and harsh weather. The results can be astonishing.

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The Dormant Tree

dormant tree
Tree still dormant in early spring. (1brettsnyder/Wikimedia Commons/CC BY-SA 3.0)

A tree prepares for winter in early fall and protects itself from winter. Leaves fall and the leaf scar closes to protect precious water and nutrients that have been collected during spring and summer. The entire tree undergoes a process of "hybernation" that slows growth and transpiration which will protect it until spring.