Background

Plants have always played a central role in the everyday workings of human societies. Investigating their historical utility can help kids understand cultural and technological evolution and how plants serve as inspiration for inventions. The process never stops: scientists, engineers, and inventors make discoveries and develop new technologies, many which result in the replacement of plant-based products with man-made ones. On the flip side, we are daily finding new uses for plants and the materials they contain, from alternative fuel sources to medicines. By exploring these less obvious uses for plants, students may develop more interest in and a deeper respect for nature…and perhaps feel stimulated to pursue some inventions of their own!

To get you started on this green adventure, below are details about six historically important plants: gourds, horsetail, papyrus, lamb’s ear, indigo, and willow.

Gourds - Our featured Plant of the Month! Click here to read all about them.

Horsetail – Horsetail (Equisetum sp.) is a plant that has survived since the time of the dinosaurs. A close relative of ferns, horsetail reproduces through spores rather than seeds. It grows in marshy areas and sports two different types of vertical, hollow stems. The first stems appear in the spring and looks something like asparagus topped with a brown cone-like structure that bears the spores. Later in the year, they produce larger stems with stringy, tough leaves branched at the joints, giving the plants a feathery appearance (like a horse’s tail). If planted in a favorable location, horsetail will spread quickly and is considered an invasive weed in some areas.

Another name for horsetail is scouring rush, which gives away one if its important uses. Horsetail has very fibrous stems that contain silica crystals, making the stems excellent implements for cleaning pots and pans. Historically, people tied bunches of horsetail stems together to form homemade scouring pads for cleaning dishes. It was also used by furniture makers to polish their wares. Even though they have been replaced by ‘SOS’ pads and sandpaper in most places, there are still cultures that use the horsetail for cleaning and polishing.

Papyrus – Papyrus (Cyperus papyrus) is native to the rivers and streams of northern Africa. It is grass-like in appearance, although it is considered a sedge rather than a grass, with feathery, umbrella-like flower spikes. As early as 3000 BC, the Egyptians used stems of papyrus plants to create a paper-like product also called papyrus. They laid papyrus stems in an overlapping pattern and pounded them into a mat. When it was dry, it formed a durable and smooth writing surface.

Papyrus was extremely important because it was lightweight and easy to transport, unlike the stone tablets it replaced. Papyrus documents helped to greatly advance the development of written languages, transfer of information, and documentation of history. It was also used by ancient Romans and Greeks. Click here for more details on how papyrus was made, or here for more information on the papyrus plant.

Although the English word paper is derived from the word papyrus, papyrus sheets are not considered true paper. Paper as we know it today was developed in China in about 105 AD -- and it also was made from plant fibers! Click here for more information on the history of paper. And be sure to check out our classroom project, Making Paper: Experience the Fiber of Learning.

Lamb’s Ear – Lamb’s Ear (Stachys sp.) is a low growing plant with fuzzy, soft, whitish-gray leaves reminiscent of the ears of lambs. Scientists trace the origins of this perennial plant to Iran and Turkey. In the past, people used its soft, absorbent leaves as bandages. While it has since been replaced by sterilized bandages made from cotton and plastic, lamb’s ear lives on as a popular ornamental plant. It is very easy to propagate by division and is great for use in herb borders and and children’s gardens.

Indigo – In the past, indigo (Indigofera sp. ) was an important source of blue pigment for dyeing textiles and crafts. Archeologists discovered indigo-based dye on Egyptian mummy wraps that date back as early as 1580 BC. There are two different species of indigo plants commonly used to produce the dye including Indigofera tinctoria (native to India and Asia) and Indigofera suffruticosa (native to South and Central America). With origins on two different continents, the plants were used widely throughout history. But indigo was most popular during the height of the spice trade in the 1500's.

To produce the blue pigment, indigo plants were harvested while in bloom, and soaked them water. Through fermentation the pigments separate from the water, creating a pasty substance that dries into a dark blue powder. During colonial times, indigo was an important crop in the southern United States, but farmers planted less of it after the Revolutionary War because they reaped more profit from cotton and tobacco farming.

As with many plant-based dyes, indigo was replaced by a synthetic version in the late 1800’s that was much cheaper to produce. Today, only dedicated fiber crafters produce indigo dye from plants. Click here for more information on indigo, and here for more information on the history of indigo.

Willow – Documents dated to the fifth century BC state that the Greeks chewed on willow (Salix sp.) bark to relieve pain, but it wasn't until the 1800’s that scientists discovered the chemical (named salicin after willow's latin name) that did the trick. A synthetic derivative of salicin is now used as the active ingredient in aspirin, the number one pain-relieving drug consumed worldwide. Although aspirin is now man-made, willow deserves the credit for its inspiration. Salicin was later identified in other plants including wintergreen, sweet birch, and a variety of rose and spiraea plants. Click here for more information.

Aspirin is just one example of a medicine derived from plants. Various sources claim that 25 to 50 percent of today's medicines are of plant origin, and new ones are still being discovered every day.

These are just a few of the plants people depended on in the past. Where would we be now if our ancestors hadn't discovered their utility?

Plant Products We Use Today

Though the historical uses of the plants above were replaced with man-made or synthetic products, there are plenty of non-food plant products that are very important today. Here are a few examples:

Cotton – Cotton is a member of the mallow family, along with other familiar plants such as hibiscus and okra. It has endured as a staple ingredient of textiles for thousands of years. Scientists are not sure of its origins, but have traced its cultivation back to Africa and Asia as early as 2500 BC, and to the west coast of the Americas in 3400 BC. Documentation of cotton clothes date back to Egypt and Pakistan back as early as 3000 BC. Though we've developed many different fabrics, both natural and synthetic, cotton is still the most common.

Cotton requires a long growing season -- approximately 150 to 190 days from seed to seed. It's a major cash crop for warm-climate farmers in 14 U.S. states. The plants have attractive flowers that yield seeds pods known as cotton bolls. When the seeds ripen, the bolls open to reveal long fibers attached to the seed, and then it's harvest time. A machine called a cotton gin separates the fibers (also known as lint) from the seed. Find related teaching tools at the Cotton Counts Educational Resource site.

Soy Ink – The soybean is a highly nutritious legume native to China, where they've been a prominent food source since the eleventh century BC. In the 1800's Europe and America began farming soybeans for livestock feed and as a green manure for nitrogen-depleted fields. But as with many field crops, such as corn and peanuts, inventors developed other edible and non-edible products from the soybean and continue to discover and formulate new uses for this humble legume.

One important soy by-product is soy-based ink, which emerged as an alternative to petroleum-based inks during the 1980’s. Soy ink offers several advantages over its predecessor, including a more stable price, decrease in pollution, and safer, easier recycling of printed paper. Today, most newspapers use soy ink for their publications. Visit the United Soy Bean Web site for more information.

Ethanol – Corn originated in Central America. Through trade and migration native peoples disseminated corn throughout the Americas, where it became a staple crop. It is now one of the most important sources of carbohydrates for people worldwide, and corn byproducts such as corn oil and corn syrup are a major ingredients in processed foods.

Beyond the kitchen, one of the newest by-products of corn is ethanol fuel, which is mixed with gasoline to fuel cars and trucks. Because corn is a renewable resource, it is being investigated as a viable option for decreasing our dependence on foreign oil imports. So as it turns out, corn fuels your body and your car, too! For more information visit the National Corn Growers Association Web site.

The list of plants we depend on each day is long and distinguished. Ask your students to keep a journal for a day and write down each time they use a product derived from a plant. They may be surprised by the number of pieces of plant-based paper they need!

Plant-inspired Inventions

The "tail" of velcro involves a dog...

Nature provides us not only with products to use, it also inspires invention. Inventors use keen observation skills to identify problems or needs and then develop solutions to address them. The process follows experimental methods – they must pose a question (hypothesis), research possible solutions, create ways to test their solutions, and then present their results. The development of Velcro is an example of a plant inspiring an invention.

Velcro was invented by George de Mestral, with a little help from his dog. He was inspired by the cockleburs (fruit of the cocklebur plant) that stuck to his pants and his dog’s fur after their walks. He observed that the burs had small hooks that would get stuck in the loops of his pants and was impressed by the strength of this natural adhesion method. He observed that the cocklebur plant had adapated this "design" over time as an effective way to disperse its seeds. In nature, animals pick up the seeds on their fur and then drop them in another location, allowing the plant to move through its habitat and ensure its survival.

George wanted to find a way to imitate this design for human use. He worked with fabric experts to create an adhesive fabric that replicated this phenomenon and developed Velcro, which works by combining strips of loops with strips of hooks. Click here for the full story of George de Mestral and his marvelous invention.

Impressed with the range of utility available from the familiar green things around you? We'll bet your students will be, too! Check out Lesson 1 and Lesson 2 for ideas on how to share this information with your students.

Copyright© 2005 National Gardening Association