tree

 What is a tree ??????

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General speaking, a tree is a tall woody structure with leaves or needles. The characteristics separating a tree from other plant organisms, such as a shrub, grass, moss, herbacious plants, liverworts, .. etc. are:

1. A woody structure
2. A single trunk
3. Roots
4. Multiple branches
5. The ability to grow tall
6. The ability to increase in all dimensions

General types of trees

Deciduous Trees Lose leaves annually angiosperm Flower ovary Fruit Closed seed Hard wood Oak Maple Elm Ash

Coniferous Trees Most are evergreen gymnosperm No flowers No ovary No fruit Nakes seed Soft wood Pine Spruce Larch Cedar

To most people, a tree is just a tall brown trunk with green (or even red or different colours) leaves, flowers and even fruits at different times of a year. A tree is just a tree! (You want to bet, even the tree would think the same!)

You heard that Red Maple is really pretty and has nice fall colours so you go to the nursery and want to get a Red Maple. Then you find out there are quite a lot of maples have red leaves. In order to indentify the right tree, a huge amount of effort have been devoted to scientifically classifying trees, following the generally accepted binomial nomenclature: a formal system of naming all the species of living things. For example, the formal binomial name for the common Red Maple is Acer rubrum, for Pin Oak, it is Quercus palustris. The first part refers to the genus, followed by the species. In other words, all true maples belong to the genus Acer, and all true oaks belong to the genus Quercus. Also there are cultivars and varieties to further identify any new species. Then there are hybrids too!

However, if you want to get a special kind of tree to improve your landscape, you need to find out more information about it, before you decide if this tree is right for you. You have to know what culture the tree needs: the soil - moist, dry, alkaline or acidic; the zone - the highest and lowest tempeartures in your area; the size of a mature tree - may be it it too big for your landscape, ...etc. Also you may want to know if it will produce messy fruits, drop a lot of leaves, weedy or it will attract some kinds of insects that will bother you. So you need to know the tree.

It is always easier to tell what tree it is when it has some special characteristics, like its leaves, its bark and its form. However some trees may drop their leaves in winter, then it is hard to tell what kind of tree they are. So let's talk about how to identifying a tree.

How to identify a tree

There are so many different kinds of trees: maple, oak, elm, birch, just to name a few. So how does one distinguish among them? The most commom tool used to identify a tree is the LEAF - its unique shape, its margin, its colours, its venetion and how the leaves are arranged on the branch, are vital keys to identify a tree.

Samples of leaf shapes, arrangements, margins, and venations:

(Source: http://en.wikipedia.org/wiki/Leaf#/media/File:Leaf_morphology.svg)

Samples of leaf of common trees in America:

(Source: http://cdn2.blisstree.com/wp-content/uploads/2008/01/leaf-types.jpg)

The other most obvious key to identifying a tree is its FLOWERS, if it any. Most people will know that's a magnolia when seeing its flower - through its shape, colour and smell (even though it may be hard to tell what kind of magnolia it is just by looking at the flower).

Pictures of flowers:

"The term 'inflorescence' refers to the arrangement of flowers on a floral axis. Most schemes that define inflorescence types separate solitary flowers from flower clusters and stipulate that an inflorescence is a cluster of two or more flowers. It is not always easy to distinguish between solitary flowers and an inflorescence..." (http://lifeofplant.blogspot.com/).

Here are some diagrams depicting some common configurations of inflorescence:

Some trees do bear FRUITS, the most obvious are fruit trees, like apple trees; but for some trees, like Maple, their fruit is a samara (a winged achene). Fruit also is another great key to identifying trees.

Pictures of fruits:

However all the above may not be availabe during Winter, when most of the leaves, flowers and fruits are gone, then there are some other special characteristics which will persist through the year for identification.

In wintertime, the first and easiest step in identifying trees is noticing whether the tree has lost its leaves, meaning it's deciduous, or if it still has its leaves, meaning that it's evergreen. If the tree is evergreen and a conifer (needle-leaved), you may be able to determine the tree's exact species by studying the size and arrangement of the needles, as well as the tree's overall size and shape. For all trees, the following should be helpful.

• Study the tree's branching formation to determine whether it's alternate or opposite. Dogwoods, ashes, maples, Viburnums and horse chestnuts have opposite branching, where the limbs and twigs grow off the main branch in pairs. Alternate-branching trees, such as sycamores, birches and tulip trees, have twigs and limbs that grow off the main branches singularly and not opposite each other.

• Look at the twigs to study where the leaf scars are located. The leaf scars can tell you where the leaves grew and how they're arranged on the twigs. Also notice the thickness of the twigs. Walnut trees have fewer but thicker twigs, while elms and maples have numerous thin twigs.

• Identify the tree by looking at its buds, which are very distinct in each tree species. For example, linden (basswood) trees have double red buds, silver maples have clustered red buds, bitternut hickories have yellow buds, horse chestnuts have sticky buds and tulip trees have duckbill-shaped buds.

• Study the bark to identify trees in winter, especially sycamores, white birches and chestnuts and certain species of hickory trees. White ash trees have ridged bark in a diamond-like pattern, most young maples have noticeably smooth bark, black cherry trees have dark small-plated bark that looks like chips, red oaks have rough-textured vertical ridges on the bark, and shagbark hickories have large, vertically-peeling thick strips of bark.

• Identify trees in the wintertime by smell. Snap a twig to smell the inner pith or peel back a piece of the outer bark. Sassafras trees have a strong spicy but pleasant smell, wild cherry trees have a bitter almond-like odor and sugar maples have a slightly unpleasant odor.

Most herbaceous plants have flowers and are favoured by most homeowners, but what will the world be without trees?! Trees are not just for decoration, they are majestic creatures, helping to maintain a well-balanced world. People use them as windbreakers, shielding wind in winter and sun in summer. It also can be used to prevent erosion, absorb noise, pollution and of course, trees are always so mysteriou