TREES
by: Joyce Kilmer (1886-1918)
I think that I shall never see
a poem lovely as a tree.
A tree whose hungry mouth is pressed
against the earth's sweet flowing breast,
A tree that looks at God all day,
and lifts her leafy arms to pray,
A tree that may in Summer wear
a nest of robins in her hair,
Upon whose bosom snow has lain;
who intimately lives with rain.
Poems are made by fools like me,
but only God can make a tree.
Trees have been in existence on the Earth for 370 million years. They provide shade and shelter for other life forms, cones, fruit and nuts for feeding them, and timber or wood for their dwellings. They provide man latex and sap for rubber and syrups, and fuel for cooking and heating.
Above ground, branches branch and spread out just as wide and divide into smaller branches and shoots that grow into leaves. The leaves absorb oxygen and capture light energy and convert it into chemical energy by photosynthesis. This energy is used to weave the carbon dioxide from the air into long chained molecules that provide the material needed by the tree for its growth and development. The shape the tree forms has a strong resemblance to the shape of its leaves it grows.
Trees are surrounded by a layer of bark which serves, like skin, as a protective barrier. Barks are the outermost layer of trees. They are mostly composed of dead cells providing the tree a thick, waterproof covering. They protect the trunk against the elements, disease, animal attacks and fire. Bark is continually replaced by a living layer of cells called the cork.
The plane tree periodically sheds its bark in large flakes.
The bark of the birch peels off in strips. The papery bark of the white birch tree was used extensively by Native Americans to cover their canoes and the permanent oval wigwams they lived in.
In some trees such as the pine, the bark exudes sticky resin which deters attackers.
Resin is a viscous liquid composed mainly of volatile terpenes and used in varnishes. Some resins contain essential oils used in incense and aromatherapy. Camphor trees produce an essential oil and the eucalyptus trees are the main sources of eucalyptus oils used in medicines and perfumes. When resin is heated and the terpenes are driven off, rosin is left behind and used on the bows for stringed instruments.
Fossilized resin, formed 145 to 65 million years ago, is known as amber and sometimes contain trapped insects and spiders.
In rubber trees, a milky latex oozes out. This sticky secretion is used to make natural rubber which is more durable than synthetic rubber.
The innermost layer of bark transports sap containing the sugars made by photosynthesis to other parts of the tree. It is a soft spongy layer of living cells, some of which are arranged end to end to form tubes.
Cork, produced from the thick bark of the cork oak, is harvested from living trees about once every ten years. More than half the world's cork comes from Portugal and is largely used to make stoppers for wine bottles. Other uses include floor tiles, bulletin boards, balls, footwear, packaging, insulation and joints in woodwind instruments.
Tannin, extracted from bark is used to tan leather to make it soft and flexible and water resistant.
Over 100 drugs come from plant sources, many of them from the bark of trees.
- Quinine originates from the cinchona tree and was for a long time the remedy of choice for the treatment of malaria.
- Aspirin was synthesized to replace the sodium salicylate derived from the bark of willow trees. The anti-cancer drug Paclitaxel is derived from taxol, found in the bark of the Pacific yew.
Below the ground, roots branch and spread out widely, anchoring the tree and extract moisture and nutrients from the soil. Roots serve to anchor the trees and gather and store water and nutrients for them.
Near the tip of the finer roots are single cell root hairs that are in immediate contact with the soil particles and absorb water and nutrients. Roots require oxygen and only a few species such as the mangrove and the pond cypress can live in permanently waterlogged soil.
Roots encounter hyphae of fungi and form mutualistic relationships with them. The tree acquires minerals from the fungus while the fungus obtains carbohydrate products of photosynthesis from the tree. The hyphae of the fungus link different trees forming a network that transfers nutrients from one place to another. The fungus promotes growth of the roots and helps protect the trees against predators and pathogens. It can also limit damage done to a tree by pollution as the fungus accumulates heavy metals within its tissue. Some trees are interconnected through their root system, forming a colony whereby all the trees in the colony are genetically identical clones. Some tree species have evolved roots that are aerial and can absorb oxygen from air.
Trees grow in spurts of active expansion followed by periods of rest. The whole year's growth may take place in just a few weeks. Before the period of dormancy, the last few leaves produced at the tip of a twig form scales. These are thick, small and closely wrapped and enclose the growing point in a waterproof sheath. Inside this bud there is a rudimentary stalk and neatly folded miniature leaves, ready to expand when the next growing season arrives.
Trees come in all sizes. Bonsai trees are miniature trees grown in small containers. This Japanese tradition dates back over a thousand years. A bonsai is created from a cutting or seedling of nearly any perennial woody-stemmed tree or shrub that is confined to grow in a small container and pruned by cutting roots, branches and leaves to keep the plants small.
Shrubs and bushes are trees with multiple stems that stop growing due to lack of nutrients in the soil.
The tallest trees are the giant redwood sequoias that live many thousands of years and grow more than 100m tall.
The goal of every living organism, including plants, is to create offspring for the next generation. Plants produce offspring by making flowers that when pollinated produce fruit which hold seeds.
Seeds are living embryos that can survive without water, air and sunshine and even the vacuum of space. Once seeds find a suitable environment, they sprout and grow into a flower producing plant.
Most flowers have both pollen producing parts and seed producing parts in the same flower.
Some plants come in 2 versions, male and female, producing flowers that are either pollen producing males:
or seed producing females.
Pollination is the act of transferring pollen from the males to the females by rain, wind or insects. Seeds and the fruits surrounding them are only produced when the flowers are fertilized by pollen.
The size of seeds is independent on the size of the tree producing them, the largest trees produce one of the smallest seeds. Sometimes the seed remains on the tree for many years waiting for a trigger event to liberate it. Fire stimulates release and germination of seeds of the jack pine, and also en- riches the forest floor with wood ash and removes competing vegetation. Ash trees and maple trees have seeds with blade shaped wings which fly far away when released by the wind. Other seeds are enclosed in edible tissue that animals eat and excrete to disperse. Nuts that are gathered and stored by animals for later eating can germinate before they are eaten.
Various parts of trees are used as spices.
- Cinnamon is made from the bark of the cinnamon tree.
- Allspice is the dried small fruits of the pimento tree.
- Nutmeg is a seed found in the fleshy fruit of the nutmeg tree.
- Cloves are the unopened flower buds of the clove tree.
- Sassafras oil is an important flavorings obtained from distilling bark from the roots of the Sassafras tree to make the popular soda drink called root beer.
Several holly species are used to make caffeine-rich herbal teas. The South American Yerba Mate is boiled for the popular drink called Mate. Pear leaves were smoked in Europe before tobacco was introduced. Wood smoke is used to preserve meats and fish as well as to tenderize and flavor them.
Wood is the hard, fibrous structural tissue found in the stems and roots of trees and other woody plants like shrubs and bushes. Wood has been used for thousands of years for both fuel and as a construction material. It is a composite of cellulose fibers embedded in a matrix of lignin. Woods of different trees have different properties and thus different uses. Cedars have a slow rate of decay and resist insects. This makes them useful for outdoor decks and fences. Firs, ashes and pines are very strong and are used for building products. Walnuts are hard, stiff and look beautiful when finished making them ideal for cabinets, furniture and veneer.
Trees exist in two different groups depending on the leaves and fruit they produce.
The gymnosperms commonly called conifers or evergreens usually have softwood and produce leaves in the form of needles that are usually not shed. Their fruit that carry their seeds are in the form of cones.
There are many types of softwoods having needles of different shapes and lengths. They are often found in colder places at higher altitudes than broad leaved trees. In many cases, their branches hang down at an angle to the trunk which decreases the likelihood of them breaking when weighed down by snow.
- Firs have single growing flat needles that usually grow out from each side. They are waxed and appear shiny on their upper side.
- Spruces have single growing round needles that grow out in all directions.
- Pines have long round needles that grow in groups around the branches.
- Cedars have flat needles that branch out somewhat resembling thin broad flat leaves with scales.
- Larches shed their needles.
The angiosperms commonly called deciduous usually have hardwood and produce broad shaped flat leaves that are shed every year. They grow flowers that turn into fleshy fruit or hard shelled nuts that contain their seeds.
There are many types of hardwoods having leaves of different arrangements. The leave can be single or composite.
Single leaves can be:
- lobed like in maple, plane or sycamore and some hawthorn.
- sinuate like in oaks and some poplars.
- rounded like in some alders, some poplars and some aspens.
- ovoid like in some alders, some poplars, some willows, beeches, birches, cherries, hawthorns, apples, hazels and elms.
- heart shaped like in limes.
- triangular like in some poplars.
- lanceolates like in chestnuts and willows.
- fan shaped like in ginkgoes.
- serrated edges like apple boxelder black cherry and most poplars.
Cedar has decay-resistant wood for outdoor construction, canoes, shingles, and guitar-making. This is the main wood for making pencils.
Pine has high-value carpentry wood used for furniture, window frames, paneling, floors, roofing, utility poles, fences, waterwheels and picture frames. Its resin is an important source of turpentine.
Spruce has wood for many purposes, ranging from general construction work and crates to musical instruments. It has long wood fibers which bind together to make strong paper. It has no insect or decay resistance qualities after logging so it is generally used only for indoor construction purposes like for drywall framing.
Fir has wood with no insect or decay resistance qualities after logging, so it is generally used only for indoor construction purposes like for drywall framing. It is often used as pulp for paper and for manufacture of plywood.
Yew has a reddish brown and very springy wood. It was traditionally used to make bows, especially the longbow. The tree is poisonous and is grown in churchyards to keep cattle away.
Hardwoods:
Alder has wood ideal for buildings in wet ground, water troughs and fencing stakes. It is used for furniture and cabinets.
Ash has ideal wood for wherever curved wood is required like in covered wagon frames, rocking chairs or walking sticks. It makes excellent axe handles as it is strong enough to resist the shock of the blow but also cushions the shock to the user. Clothespins are made from ash wood.
Beech has a lightweight wood often used as drawers, spinning wheels, carpenters tools, mallets and handles. It is used for foundations of buildings where the ground is very wet.
Birch has wood ideal for toothpicks, clothes pegs, bowls, spoons, wood-block floors and as veneers. It is used as firewood due to its high calorific value per unit weight and unit volume. It burns well, without popping, even when frozen and freshly hewn. The bark will burn very well even when wet because of the oils it contains. With care, it can be split into very thin sheets that will ignite from even the smallest of sparks.
As a tone-wood, it carries sounds well and is among the most sought-after wood in the manufacture of speaker cabinets. Birch has a natural resonance that peaks in the high and low frequencies, which are also the hardest for speakers to reproduce. This resonance compensates for the roll-off of low and high frequencies in the speakers, and evens the tone. It is also a common material used in mallets for keyboard percussion. Drums are often made from birch. Wood pulp made from birch gives relatively long and slender fibers making highly transparent papers.
Blackthorn makes an excellent fire wood because it burns slowly with a good heat and little smoke. The wood takes a fine polish and is used for tool handles, canes, walking sticks and clubs.
Box wood grows very slowly making boxwood one of the hardest wood in Europe. It is heavy and free of grain produced by growth rings, making it ideal for cabinet-making, the crafting of clarinets, engraving, wood-turning, tool handles, mallet heads and as a substitute for ivory.
Chestnut wood is very resistant to rot and often used in fencing and poles for scaffolding. Usually it is too 'soft' for cabinet making but often used as inlay. Chestnut is of the same family as oak, and likewise its wood contains many types of tannin. This renders the wood very durable, gives it excellent natural outdoor resistance, and saves the need for other protection treatment.
Elm wood is valued for its interlocking grain, and consequent resistance to splitting. It has a twisted grain which gives great strength for wheel hubs, floor boards, and keels and rudders in boat building. It bends well and distorts easily making it quite pliant.
Hornbeam wood is the hardest British wood. It is used for cogs in wind and water mills or anything needing a screw thread. It is also used for musical instruments.
Lime wood is lightweight but strong and stable. It is easily carved and used for ornamentation on furniture, dug-out canoes, spoons and ladles. It has strong fibers for woven goods and cordage. The wood is used in marionette, puppet making and carvings as it has a fine light grain and is light in weight. Because it is easy to carve and has good acoustic properties, it is used for musical instruments.
Maple wood has a beautiful grain and is used to make bowls, drinking vessels, pipes and carries sound well making it ideal for musical instruments. It is the wood of choice for bowling pins, bowling alley lanes, pool cue shafts, and butcher's blocks. Maple wood is also used for the manufacture of wooden baseball bats, though less often than ash or hickory due to the tendency of maple bats to shatter when broken. Maple is also commonly used in archery as the core material due to its stiffness and strength.
Oak wood has high density, great strength and hardness, and is very resistant to insect and fungal attack because of its high tannin content. It makes excellent railway ties to hold the steel rails. It also has very appealing grain markings making it a an excellent wood for furniture, deckchairs, boats and ships, wooden frame houses, carved work, wine casks, and field gates. It is used to make charcoal, the fuel in barbecues and the fuel used by blacksmiths to make steel from iron. Char- coal is produced by slow burning of wood, often oak, over a time span of 15 hours.
Pear has wood that is one of the preferred materials in the manufacture of high-quality woodwind instruments and furniture. It is also used for wood carving, and as firewood to produce aromatic smoke for smoking meat or tobacco. Pear wood is valued for kitchen spoons, scoops and stirrers, as it does not contaminate food with color, flavor or smell, and resists warping and splintering despite repeated soaking and drying cycles. It is a very stable wood ideal for measuring instruments such as set squares and T-squares. It is the favored wood for architect's rulers because it does not warp. It is similar to the wood of its relative, the apple tree.
Poplar wood is renowned for having the durability of oak but with at a substantial reduction in weight. Because poplar grows very fast, it is widely used for the manufacture of paper. It is also sold as inexpensive hardwood used for pallets and cheap plywood. More specialized uses include chopsticks, matches, the boxes in which Camembert cheese is sold, baskets, floorboards and arches of framed buildings. Poplar wood is also widely used in the snowboard industry because it has exceptional flexibility.
Sycamore wood is used for butcher's blocks, boxes and crates, furniture, siding, and musical instruments.
Walnut wood is used for elaborate carving in furniture and for gun stocks as it has good shock absorbency.
Willow wood is used for cricket bats, clothespins and furniture.
Man has been able to produce many synthetic materials that are similar to those produced by nature. Fabrics made from silk, cotton and wool and leather hides and furs of animals have been to a large extent re- placed by synthetic materials. Man has however not been able to yet produce a material with the properties of wood.
The easiest way to identify trees is by their leaves and seeds and fruit.
Can you identify some of the following trees?
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THE END
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