Wardian Case

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Wardian Case

by Michael O’Brien

Named for Dr. Nathaniel Ward, the wardian case is considered to be the precursor of the modern terrarium. Not only did the modern terrarium make it possible to grow plants indoors, but the wardian case is said to have had an impact far beyond our homes. We have come to appreciate the sheer beauty of Mother Nature and how our planet works. What Dr. Ward discovered can be equated with the broader systems that control life on planet Earth. His wardian case behaves in very much same way as the natural water cycle which makes all life on this planet possible.

Wardian Cases For Plants

As many of us learned in school, water is essential to our survival. The rain or water cycle occurs on a constant basis all around the planet. Think of the water cycle as recycling in its purest form. Simply put, water on the surface evaporates into the atmosphere and eventually falls back to Earth in the form of precipitation. Precipitation can be defined as any climatic event which causes water to leech or condensate from the atmosphere. Rain, sleet, snow, hail, dew and even fog are all common forms of precipitation.

At any given time, there are millions of tons of water circulating in the atmosphere. This circulation is constant and never stops. This is the proverbial drop in the bucket compared to the water on the surface. The oceans make up over seventy percent of the Earths surface and over ninety percent of our water is found in the oceans. Surface water evaporates, whether from the surface of the ocean or a puddle in the street. Evaporation is simply defined as a liquid being converted to a gas, always below the temperature at which water boils. This process is different from the conversion that occurs when water is boiled and turns to steam.

The most visible evidence of atmospheric condensation can be seen in the formation of clouds. Cooler air at the upper levels of the upper atmosphere causes the water vapor to cool and form water droplets. These water droplets remain suspended in the air and produce various types of clouds. At very high altitudes, condensed water freezes and forms ice crystals producing the thin, wispy cirrus clouds we often see. The rate at which surface water evaporates varies a great deal. One thing that remains constant is the water cycle. The Earth's atmosphere acts in much the same way as a Wardian case.

What makes the invention of the Wardian case so interesting is how it was discovered. Like so many scientific discoveries, Dr. Ward stumbled on his idea through an unrelated observation. The story is relatively simple. Among his other interests, Ward was an amateur entomologist and botanist. In his London home, he collected thousands of insect specimens. In the mid 1800's, London was known to be engulfed in coal smoke which in turn produced the phenomenon known as acid rain. Acid rain occurs when the acids in the air bond with water molecules. As a result, many species of outdoor plants would die off, unable to withstand the effects of an acid environment. On a larger scale, acid rain has adversely affected lakes and streams hundreds of miles from the source.

According to a 2002 newspaper account, Dr. Ward was working the chrysalis of a hawk moth in 1829. He reportedly sealed the moth chrysalis in a bottle with some organic material. What he observed was not what he expected. On the organic material, inside the sealed bottle, ferns and grasses had sprouted. Ward observed that the organic material in the bottle had remained damp and theorized correctly that the moisture in the bottle would condensate on the top and sides of the bottle. Gravity would cause the condensation to fall, keeping the organic material moist, providing the moisture needed for the seedlings. According to the report, the ferns and grasses survived inside the sealed bottle for over four years.

To further observe this phenomenon, Ward commissioned the construction of a larger wooded box. The box was constructed with glass panels to allow light to enter the enclosure. Using the tightly sealed box, Ward was reportedly able to replicate his initial observations. To further prove his theory, Ward is said to have constructed two larger cases, shipping both from England to Australia in 1833. Each case contained a variety of grasses and ferns that arrived in Australia no worse for wear and tear. In should be noted the sea journey took the ship around Cape Horn and lasted for some months.

What came to be known as Wardian cases had a significant impact on trade and the expansion of agriculture. Wardian cases became a way to transport plant species long distances for long relatively long periods of time. For example, Wardian cases were used to transplant tea plant seedlings from China to India and other points in the South Pacific.

The modern day terrarium is a direct descendent of the Wardian case. A properly constructed terrarium can closely replicate the Earth's water cycle, trapping and recycling the available moisture. A well constructed terrarium is great for anyone who has struggled to grow plants indoors. Growing plants indoors is complicated by the ambient room conditions and even the seasons.

During the winter months, the air inside our homes tends to be dryer. Controlling the moisture content of a potted plant with exposed soil becomes very difficult. Moisture in the soil is drawn off in two ways. The plant itself removes moisture from the soil and the moisture must be replenished. The natural process of evaporation is also at work. Some plant species can survive or even thrive indoors. Other species such as ferns are much more sensitive to changes in the growing conditions. Even under the best conditions, it is easy to over or under water indoor plants.

A properly maintained terrarium is the ideal place to bring the wonder and beauty of Mother Nature into our homes. The simple observations of Dr. Ward and the invention of the Wardian case has made possible the minor miracle of the terrarium.