Why Study Plants?

Clickable Index of Reasons to Study Plants
OxygenOzoneFood
FiberWood and PaperFossil Fuels
MedicinesLatexPitch and Resins
Essential OilsDecorationJobs

Some History and Biochemistry

Oxygen

If we go back in time some 4.5 billion years before present, our planet was composed of a mineral earth with some surface waters (ocean) and an atmosphere of gases with weather patterns. There was no life on our planet at that time. The atmosphere was different from what it is now:

Ancient Atmosphere:

H2O + N2 +NH3 + CO2 + CO + CH4 + H2 + H2S

As you might notice, this is an anaerobic (no oxygen gas) atmosphere with many components that would be toxic to much of life as we know it now.

If we then move up in time to just 3 billion years before present, after more than a billion years without any life on earth, we find our first evidence of life on the planet. These newly appearing organisms used fermentive pathways and primitive forms of photosynthesis that were insensitive to the toxic elements of the atmosphere. In some very recent research it appears that this photosynthesis included only about half of the light reactions that we know about now. The earliest forms of photosynthesis appeared in prokaryotic cells (cells lacking a nucleus) which we would probably classify today as cyanobacteria (blue-green algae).

We can define photosynthesis as this reaction:

CO2 + H2O light
------>
chlorophyll
CH2O + O2

As you should immediately notice, this reaction has the potential to change the atmosphere in important ways. The carbon dioxide of the atmosphere is combined with water in the ocean (from around the cells) using the energy of light to produce carbohydrates (more on that below) and oxygen gas. Thus if photosynthesis is carried out on a large enough scale and for sufficient time, the carbon dioxide gas concentration would be reduced and the atmosphere would have oxygen in it for the first time.

These ancient cells populated the vast oceans of that time and carried out photosynthesis for 1.5 billion years before there was any kind of eukaryotic (cell with a nucleus) organism on the planet! In that much time earth's atmosphere was changed to what we now recognize as our own...more than 70% nitrogen, around 20% oxygen, and small amounts of other gases. This transformed atmosphere is aerobic, and the presence of oxygen permits life based on respiration to exist. The transformation permitted eukaryotic organisms to evolve.

Plants provide the Oxygen we breathe

Ozone

The oxygen gas in the atmosphere is routinely converted to ozone by natural processes:

O2 ---> O3

This ozone absorbs ultraviolet light coming from the sun. Prior to the aerobic atmosphere, the ultraviolet exposure on earth's land and upper layers of ocean must have been severe. This light causes mutation in the genetic material and must have resulted in rapid rates of genetic change. After photosynthesis put oxygen into the atmosphere, the resulting ozone provided a protective shield allowing life to exist with much less mutation. It provided stability for life as we know it.

Plants provide the Ozone UV screen

Now if we move up to 1.5 billion years before present we find the first eukaryotic cells... those with a true nucleus. These single-celled organisms would ultimately evolve into vascular plants, fungi, and animals. Some of the first steps in this evolution involve the development of the pathway called respiration:

CH2O + O2 -----> CO2 + H2O + energy

It is important to note that all plants, fungi, and animals use this same pathway. They acquired it very anciently by taking in a respiring bacterium as an endosymbiont (an organism living mutualistically within another organism). These endosymbionts are now called mitochondria. Based on recent DNA analysis, the eukaryotic organisms that later became plants added the photosynthetic pathway by acquiring a photosynthetic bacterium as an endosymbiont, now called chloroplasts. Thus plants have both photosynthesis in chloroplasts and respiration in mitochondria, so plants are really more than animals.

By 0.5 billion years before present there were eukaryotic algae and invertebrate (no backbone) animals populating the oceans. By 0.25 billion years ago, amphibians and arthropod animals invaded the land as did fern-like plants. By 0.12 years before present we had fish in the ocean and dinosaurs, insects, ferns, conifers, and the first flowering plants on land. By 0.05 billion year before present mammals arose to prominence on land. It wasn't until 0.003 billion years before present that the first "humanoid" evolved; Australopithecus afarensis. Our species in its archaic form did not show up until about 250,000 years before present as Homo sapiens and the modern form we would recognize as "ourselves" first appeared on earth only about 28,000 years before present.

Put in other terms, there were 3 billion years of photosynthesis before we got here. The flowering plants beat us on the planet by 90 million years. And our stunning human achievements in recorded history go back only 4,000 years! We are definitely a "Johnny come lately" and the length of our stay on earth so far is the briefest of moments in the time of life on our planet.

Carbohydrates and Relatives

Another look at the photosynthesis reaction gives us additional reasons to study plants:

CO2 + H2O light
------>
chlorophyll
CH2O + O2

The carbohydrate product of this reaction (CH2O) is really just a symbol of many possible carbohydrate and carbohydrate-related biomolecules that plants can make. The diversity of chemicals here is mind-boggling and is part-and-parcel of many businesses and industries. We can think of at least some of this as food.

Included here are the grains in which the carbohydrate is mostly starch. In this category we have pasta, bread, breakfast cereal, desserts all made from such grains as wheat, barley, corn, and rice. Here, under starches, too are tubers and roots such as potatoes, poi, and yams. In other species the carbohydrate is converted to fats; under oils we have soybean, corn, peanut, palm, coconut, sunflower, olive, safflower, and many others. These are important sources of dense energy as food. In yet other species the carbohydrate is stored as simple sugar as in fruits: grapes, figs, olives, dates, pomegranates, mulberries, bananas, oranges, mangoes, guava. In still other species the sugar is stored in stems (sugarcane) or roots (sugar beets) which we can harvest to stir into coffee or sprinkle on cereal. From other plants, we eat a mixture of carbohydrate forms and derivatives that provide balance in our nutrition. These include the "vegetables": tomato, lettuce, celery, carrot, melon, asparagus, broccoli, etc. The plants convert the carbohydrate into nitrogen-containing protein as well. Plant foods high in protein include beans and many other vegetables.

Regardless of how we think of the vegetable contributions to our diet, these plants are also the foods of animals, which we also consume as food. So plants are the source of energy and protein for animals to make pork, chicken, and beef as well as the ultimate source of milk, eggs, and cheese. In fact, as the basis for the entire food web (food chain), plants are responsible for feeding all the animals on the planet. We are completely dependent upon plants for our oxygen as well as our food!

Feeding our huge population is an increasing concern. Eating plants rather than animals (becoming a vegetarian) makes feeding the world more efficient. To make one kilogram of beef it takes 10 kilograms of grain! It is more efficient to eat the grain ourselves! In fact one bushel of corn provides enough energy and protein for 23 people! Plants are an efficient source of food and provide us with a very diverse diet of foods from which to choose.

Plants provide a diversity of food

Fibers

Not all carbohydrates are digestible, though. The indigestible carbohydrates include cellulose (similar to starch in form, but different enough to not be digestible by humans and most other animals). We sometimes refer to indigestible carbohydrates as "fiber" in our diet. While we cannot digest fiber, it is nevertheless very useful to us...

Cellulose in plants is deposited into large volumes of tissue called xylem. In some plants these fibers are long and slender and can be spun together to make thread. This thread can be woven or knitted into fabrics including linen (from flax fiber) and cotton (from fruit fibers). In fact our town, Willimantic, CT, was world-famous between 1860 and 1970 as a leader in thread-making. It still is sometimes referred to as "Thread City" but its true mark was made as the world's leading producer of linen fabric from that thread.

Alas, this fame was fleeting and the industry is gone. Now the mills are converted for other uses or are being torn down. The industry was put out-of-business by the 1970s polyester double-knit fad. That clammy, then smelly, scratchy fabric needed no ironing, washed beautifully, and held brilliant colors. The synthetic was not made in Willimantic. Of course famous drug addicts ignited their polyester clothing accidentally while free-basing on cocaine, and the lack of comfort eventually moved people toward blends, but before natural threads came back into popularity Willimantic's industry was finished.

There had been some warning about synthetics, though. Plant fibers could be chemically digested, repolymerized, and extruded into semi-synthetic fibers called rayon and nylon. These materials were the forerunner of polyester, but never really caught on with the public except for hosiery and limited shirting fabrics.

Plants provide fibers

Wood

In plants, large concentrations of xylem made the tissue we know of as wood. This useful material forms the trunks of trees and can be cut into lumber for building houses and ships. It can be burned as fuel for heating homes and cooking food. It can be chipped into individual fibers for digesting into nylon and rayon, or the fibers sized together into sheets of paper. The paper provides a writing surface, a decorating cover for walls and gifts, single-use (disposable) dishes and clothing, and so on.

Plants provide wood and paper

Fossil Fuels

Not all of the plant carbohydrate was eaten with 3-billion years of plants living and dying before animals started eating up everything produced. The bacteria and fungi probably digested some of the excess plant material, but much of it remained piling up in the ancient landscape. The piles were covered over and buried deeply by sediments. The buried vegetation initially decomposed to form natural gas (CH4) in part. Some of that methane was released back into the atmosphere as swamp gas, and the flammable gas sometimes ignited causing swamp fires. But the deeper buried methane collected underground in many places which we tap today to power our electric plants, heat homes, cook, and so on. Some of the vegetation was compressed and formed coal which is also used in electrical generation. Yet more of the deposits formed crude oil which is the source of a range of hydrocarbons for making plastics of all sorts as well as other synthetic molecules.

So a plant was the ultimate source of the gasoline in your car, the grease in its axles, as well as home heating oil, and the electrical energy that powers the lights and your hair dryer. The oil is the source of plastics in your telephone and computer, your car and your house. It provides the energy to refine metals for your jewelry, machinery, nails and screws, aluminum siding, and copper wire. In fact, even that polyester double-knit fabric was made from fossil fuels, so even it was a derivative of plants!

Plants provided fossil fuels

Medicines

Fossil fuel is also converted into a wide range of synthetic compounds including alcohol and a wide range of medicines. Of course plants are a source of medicines directly. The origins of medicine are tied up with plants. Alcohol was produced from starch early in civilization for use as a beverage preservative, but also as a surface sterilizing agent. Quinine from plant bark prevents malaria. Morphine, codeine, and cocaine are useful as local anesthetics and serve other purposes through side effects too. Digitoxin from foxglove has been used to regulate heartbeat. Caffeine from plants is an important daily stimulant for many humans. Nicotine and Δ-9-THC are important recreational drugs. There are probably many more important medicines to be found in the tropical forests of the world where countless species remain unknown. Yet we burn rain forests there at an alarming rate. For a few acres to grow corn we may lose the one species that will solve the AIDS epidemic or cure cancer. We need to preserve the biodiversity found in these tropical forests, and to do so by paying the indigent native peoples what their holdings are worth!

Plants provide medicines

Latex

Plants produce other compounds that are not particularly edible or useful as fuel, but are nevertheless important for people. One such compound is latex. Rubber trees in the tropics bleed a kind of sap when wounded that we can harvest as latex. This natural rubber can be used for making gloves for surgery and dish washing, or washers and water-tight seals, or condoms for safer-sex. If this isn't important to you right now, perhaps it will be someday.

The latex can be combined with sulfur and formed into vulcanized rubber that makes really tough tires and v-belts for running our machinery and transporting our cars down the road. If our cars ran on steel wheels the ride would be pretty lousy.

Plants provide latex

Pitch and Resins

Other species of plants have a different kind of sap product. You get it on your hands when you climb a pine tree. It is called pitch. This was used to make wood ships float without waterlogging the wood. A coating made the lumber water-resistant. The eastern seaboard states of the US had huge forests of pine which were used to make ships and coat them with pitch. These ships permitted our young and very small and limited power colonies to defeat the world's greatest power at the time of our American Revolution. The forests you see today are secondary growth. The original woods are mostly gone. The US Constitution was built in the early days of our country and some of its timbers have stood the test of time thanks to pitch. If your ancestors came to America by ship, you can thank plants for the ship, its water-tightness, the sails, and the rigging!

Pitch is also the source of turpentine and other resins for making varnish and paints. These coat and protect wood for both function and beauty. The Victorian homes of Willimantic are sometimes called "Painted Ladies" because of the many different colors of paint used. So not only are the plants the source of the building material, they produced the materials for protecting and beautifying the wood as well.

Plants provide pitch and resins

Flavors and Fragrances

Plants produce a wide range of essential oils. These are very attractive to humans. We use them to make our homes and bodies smell better and our food to taste better. They were the reason for the exploration leading to the European "discovery" of the "New" World. Your incense is a plant product. Citronella candles help repel mosquitoes from your picnic table. Jasmine, Gardenia, Lily, and other flowers provide essential oils for perfumes. Pepper, cinnamon, nutmeg, vanilla, cloves, and mint provide very important fragrances and flavorings for foods.

Plants provide essential oils

Decoration

We have quite a few reasons to study plants so far and I haven't even mentioned the one most people think about, decoration. We use plants in landscaping our towns, businesses, and homes. We bring plants into our homes as houseplants and decorate our end tables and dinner tables with flower arrangements. We give flowers as gifts and put corsages on formals and tuxedos. We use them in ceremonies such as baptisms, weddings, and funerals. From birth to death we decorate our lives with plants. Nursery and floristry is the third-largest business in Connecticut! Most people don't know that.

Plants provide decoration

Jobs

Plants have been a constant source of business and employment throughout human history. When we think about what people and plants do together we need to look toward the past first. The following is a table showing the percentage of the US population engaged in farming.

Year% Population
as Farmers
179090.0 %
194020.0 %
19686.0 %
19932.5 %

This change looks like a disaster for human employment. It is misleading. First you will notice that before 1940 most of the people in America were farmers of one kind or another. You had to be a farmer to survive--you grew your own food fresh because preservation was primitive, storage was difficult, etc. If you wanted a chicken dinner you raised grain to feed the chicken for months, then went out to the barn, grabbed a chicken, killed it, dressed it, cooked it, served it, and ate it. The discovery of fossil fuels and development of farming equipment (tractors), and the passage of the Morrill Act (signed by Lincoln in the 1800s) permitted people to leave farming per se and become employed in the industrial revolution. Individual families did not have to farm because each farmer could be so much more productive that they could support whole communities. The machinery accelerated and streamlined farming processes and the Morrill act provided the intellectual weapons to improve crops and crop management through the land-grant universities it established in each state. The University of Connecticut is the land-grant college in our state.

The number of farmers has steadily declined since then to now very low levels in the US. But this is misleading because of the separation of the many tasks carried out by farmers in earlier times. If you read about the chicken dinner carefully above, you realize that the industrialization of farming has dissected the work. Sure less than 2.5% of the population is on tractors in America. But the farmer on the tractor just grows the grain to feed the chicken. Frank Purdue buys the grain from the farmer and it is transported to the industrialized coops by a transportation network of haulers (maybe represented by Teamsters Unions?). Purdue and his employees and the truckers are not counted as farmers, but these jobs were counted as farming in earlier times. The gasoline refiners to fuel the trucks and tractors, and the fertilizer companies and pesticide manufacturers for raising the grain are now part of the farming operation now too. The machinery needs repair and design and engineering teams, and this is before we even start feeding the chickens. The coop needs light and ventilation so now we have to figure in the energy businesses such as Northeast Utilities and Connecticut Light and Power. These are part of what was originally "farming" too. Purdue's people do the chicken raising, killing, and dressing now and they aren't counted as farmers. There is more transportation now because the consumers are not on the farms or near the coops, so the chicken must be packaged. Enter more engineers and laborers into the mix. Add more truck manufacturers, drivers, fuel company staff, repair business people, parts suppliers, tire manufacturers and salespeople, etc. to the thinking. Add then the grocery store or distribution center and its staff of people. They carry out the former farmer's role of bringing the dead chicken to the home. Stock people, cashiers, baggers, janitors, all of these jobs fit in here. If the chicken goes home it then gets into family cooking, but if it goes to a restaurant, you now have to add a chef, waitresses, hostesses, bussers and dishwashers to the picture. Oh, and we mustn't forget marketing. Advertising and media jobs help to focus consumers on particular brands of chicken and particular restaurants, etc.

My point is this: rather than all of us doing all the jobs involved in farming, we are all doing some of the jobs that formerly occupied people as farmers. The dissection of the farming tasks have created a myriad of career choices for American citizens. In other words 90% of the population is still involved in what was farming in 1790. We have simply renamed and refined the jobs. If we add the rest of farming tasks into the employment picture: gardening, recreation, parks, research, breeding, genetic engineering, agronomy-field crops, entomology-insect pests, plant pathology-plant diseases, horticulture--we have a huge number of jobs for people.

Horticulture alone can be divided into several subcategories:

Pomology-fruits
Viticulture-grapes
Enology-wine
Olericulture-vegetables
Post-harvest Physiology-storage, processing
Ornamental Horticulture-landscape plants
Landscape Architecture-design
and so is amazingly large in terms of human jobs!

Plants provide jobs

If you think hard about it, and review everything above, you will see that plants are at the foundation of just about every human endeavor. This gives us very good reasons to study plants. Employers are looking for people with the knowledge and skills needed to function most productively in business and industry. By learning about plants, you add to the necessary qualifications to land you a job or assist in your promotion on the job. Biology is a great major and is a wonderful minor in college! Today business majors, for example, are a dime a dozen, but a business major with a biology minor (or better a double-major!) is a hot prospect!

Botany, the study of plants, then is the umbrella discipline that provides all of this knowledge and experience for you. By adding this to your credentials you become a more valuable job candidate and a more valued employee. Not everyone has noticed the connection between botany and business and human survival and so they have not availed themselves of this opportunity; too bad for them. Congratulations on making a fine choice of course of study!

 

This page © Ross E. Koning 1994.

 

 

Go to the Course Schedule Page.

 

Go to the Plant Physiology Information Homepage.

 

Send comments and bug reports to Ross Koning at koningre∂gmail⋅com.