Order in Nature

All living plants and animals can be grouped and organized into a simple hierarchy.

  • Who Discovered it?: Carl Linnaeus
  • Year of Discovery: 1735

How was it Discovered?

Carl Linnaeus hated disorder. He claimed he could never understand anything that was not systematically ordered. Born in Sweden in 1707, he was supposed to become a priest like his father. But Carl showed little aptitude for, and no interest in, the priesthood and was finally allowed to switch to medicine.

He entered the University of Lund’s School of Medicine in 1727 but spent more time in the university’s small botanical garden than in class. Linnaeus had been fascinated by plants and flowers since he was a small child. In 1728 Linnaeus transferred to the University of Uppsala (partly because they had bigger botanical gardens). There he read a paper by French botanist Sebastian Vaillant that claimed (it was considered shockingly revolutionary at the time) that plants reproduced sexually and had male and female parts that corresponded to the sexual organs of animals.

The idea appealed to Linnaeus. As an obsessive cataloger, he had always detested the notion that each of the thousands of plants he saw in botanical gardens was individual and separate species. Linnaeus began to wonder if he could use the differences in plants’ reproductive parts as a means of classifying and ordering the vast array and profusion of plants. His dream of bringing order to the chaos of nature was born.

Glib, cordial, and with a natural talent for ingratiating himself with rich and powerful supporters, Linnaeus was able to arrange financial support for a series of expeditions across different areas of Sweden to study and catalog plant species. He spent months tramping across the countryside listing, describing, and studying every plant he found. His expeditions were always the picture of perfect order. He started each day’s hike precisely at 7:00 in the morning. Linnaeus stopped for a meal break at 2:00 P.M. He paused for a rest and lecture break at 4:00 P.M.

During these expeditions, Linnaeus focused his studies on the reproductive systems of each plant he found. Soon he discovered common characteristics of male and female plant parts in many species that he could group into a single category. He lumped these categories together into larger groups that were, again, combined with other groups into yet larger classifications. He found that plants fit neatly into groups based on a few key traits and that order did exist in the natural world.

By 1735 he had described more than 4,000 species of plants and published his classification system in a book, Systema Naturae. This system described the eight levels Linnaeus finally built into his system: species, genus, family, order, Class, Subphylum, Phylum, and Kingdom. This system—based solely on the sexual elements of plants and (later) animals—was controversial with the public. But botanists found it easy to use and appealing.

Linnaeus’s system spread quickly across Europe and was often drawn as a tree, with giant branches being classes, down to the tiniest twigs of species. From these drawings came the concept of a “Tree of Life.”

Linnaeus spent the next 30 years touring Europe adding new plants to his system. In 1740 he added animal species into his system. By 1758 he had described and classified 4,400 animal species and more than 7,700 plant species.

In 1758, with the tenth edition of his book, he introduced the binomial (two-name) system of naming each plant and animal by species and genus. With that addition, Linnaeus’s system was complete. He had discovered both that order existed in the natural world and a system for describing that order—a system still very much alive and in use today.


Fun Facts: The world’s most massive living tree is General Sherman, the giant sequoia (Sequoiadendron giganteum) growing in the Sequoia National Park in California. It stands 83.82m (274.9 ft.) tall and has a diameter of 11.1 m (36 ft., 5 in.). This one tree is estimated to contain enough wood to make five billion matches—one for almost every person on Earth.



Plants use sunlight to convert carbon dioxide in the air into new plant matter.

  • Who discovered it?: Jan Ingenhousz
  • Year of Discovery: 1779


How was it discovered?

Photosynthesis is the process that drives plant production all across Earth. It is also the process that produces most of the oxygen that exists in our atmosphere for us to breathe. Plants and the process of photosynthesis are key elements in the critical (for humans and other mammals) planetary oxygen cycle.

When Jan Ingenhousz discovered the process of photosynthesis, he vastly improved our basic understanding of how plants function on this planet and helped science gain a better understanding of two important atmospheric gases: oxygen and carbon dioxide. 

Modern plant engineering and crop sciences owe their foundation to Jan Ingenhousz’s discovery.

Jan Ingenhousz was born in Breda in the Netherlands in 1730. He was educated as a physician and settled down to start his medical practice back home in Breda.

In 1774 Joseph Priestley discovered oxygen and experimented with this new, invisible gas. In one of these tests, Priestley inserted a lit candle into a jar of pure oxygen and let it burn until all oxygen had been consumed and the flame went out. Without allowing any new air to enter the jar, Priestley placed mint sprigs floating in a glass of water in the jar to see if the mint would die in this “bad” air. But the mint thrived. After two months, Priestley placed a mouse in the jar. It also lived proving that the mint plant had restored oxygen to the jar’s air. But this experiment didn’t always work. Priestley admitted that it was a mystery and then moved on to other studies.

In 1777, Ingenhousz read about Priestley’s experiments and was fascinated. He could focus on nothing else and decided to investigate and explain Priestley’s mystery. Over the next two years, Ingenhousz conducted 500 experiments trying to account for every variable and every possible contingency. He devised two ways to trap the gas that a plant produced. One was to enclose the plant in a sealed chamber. The other was to submerge the plant.

Ingenhousz used both systems but found it easier to collect and study the gas collected under water as tiny bubbles. Every time he collected the gas that a plant gave off, he tested it to see if it would support a flame (have oxygen) or if it would extinguish a flame (be carbon dioxide).

Ingenhousz was amazed at the beauty and symmetry of what he discovered. Humans inhaled oxygen and exhaled carbon dioxide. Plants did just the opposite sort of. Plants in sunlight absorbed human waste carbon dioxide and produced fresh oxygen for us to breathe. Plants in deep shade or at night (in the dark), however, did just the opposite. They acted like humans, absorbing oxygen and producing carbon dioxide.

After hundreds of tests, Ingenhousz determined that plants produced far more oxygen than they absorbed. Plants immersed in water produced a steady stream of tiny oxygen bubbles when in direct sunlight. Bubble production stopped at night. Plants left for extended periods in the dark gave off a gas that extinguished a flame. When he placed the same plant in direct sunlight, it produced a gas that turned a glowing ember into a burning inferno. The plant again produced oxygen.

Ingenhousz showed that this gas production depended on sunlight. He continued his experiments and showed that plants did not produce new mass (leaf, stem, or twig) by absorbing matter from the ground (as others believed). The ground did not lose mass as a plant grew. Ingenhousz showed that new plant growth must come from sunlight. Plants captured carbon from carbon dioxide in the air and converted it into new plant matter in the presence of sunlight.

Ingenhousz had discovered the process of photosynthesis. He proved that plants created new mass “from the air” by fixing carbon with sunlight. In 1779 he published his results in Experiments Upon Vegetables. The name photosynthesis was created some years later and comes from the Greek words meaning “to be put together by light.”

Fun Facts: Some species of bamboo have been found to grow at up to 91 cm (3 ft.) per day. You can almost watch them grow!