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5/10/02

Contacts:
Barbara Ambruzs, Plant Pathology, (515) 294-1741, ambruzs@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

Yard and Garden Column for the Week Beginning May 10, 2002

Tiptoe Through the Broken Tulips

By Barbara Ambruzs
Plant Pathology
Iowa State University

What's this about broken tulips? To explain, let's go back to 17th century Holland when a Dutch botanist named Carolus Clusius performed breeding experiments on tulips from Turkey. You may wonder why he didn't use tulips that came from Holland. A common misconception is that tulips originated in Holland. In fact, they really came from Turkey and parts of Asia, where they grew wild. In the late 1500s they were brought to the Netherlands. Interestingly, the word tulip is derived from the Turkish word for turban.

Clusius noticed that on rare occasions some tulip petals developed abnormal, but beautiful, patterns known as color breaking. Tulip breaking or color breaking happens when flowers that are normally a solid color aren't able to produce pigment in some sections of their petals. As a result feathered and flame-like patterns develop. These ornate tulips are also known as Rembrandt tulips.

When people saw these unusual, stunning flowers, they often wanted one for their garden. Because color breaking was rare, the coveted tulips were very valuable. Sometimes plants were stolen and sold for profit. "Tulipomania" (there was actually a craze), peaked in the 1630s. Bulbs were extremely expensive. One bulb could be traded for eight fat pigs, four fat oxen, 12 fat sheep, 24 tons of wheat, 48 tons of rye, two hogsheads of wine, four barrels of beer, two tons of butter, 1,000 pounds of cheese, a silver drinking cup, a bed, a package of clothes and a ship.

Unfortunately, color breaking is unreliable. It's not possible to predict whether a prized bulb will produce an ornate flower until it blooms. Another shortfall of these special tulips is their weakness in comparison to normal tulips. Flower size, seed set and pollen production were reduced. Varieties eventually were lost because the plants had poor vigor.

In the 1930s it was discovered that a virus caused tulip color breaking. In fact, at least five different viruses can cause color breaking. One of the viruses is called tulip breaking virus or TBV, which makes it easy to remember. The virus particles can spread from plant to plant either by the movement of plant sap or by aphids.

Viruses are very small particles. They can't be seen with the naked eye or even a regular light microscope. Powerful microscopes are needed to see viruses. Fortunately, other types of lab tests are available to help with the diagnosis of many virus diseases.

Viruses can't reproduce on their own. They use the cells of other organisms, such as plants and animals, to manufacture more of themselves. The infected plants or animals frequently become sick or lose vigor. Not everyone considers viruses as organisms. They are made up of chemical molecules such as protein and DNA (the molecule in genes), the same material found in animals and plants.

Virus-infected variegated tulips are no longer available for sale. However, occasionally a virus infected variegated tulip will turn up in nature. Today there are look-alikes, also called Rembrandt type tulips, that were genetically bred to have flame and feather patterns. They are just as beautiful as the virus infected flowers, but aren't weakened by the virus infection. It can take up to 25 years to breed a new variety that can be brought to market. Several available Rembrandt type tulips are listed below.

Union Jack - red and white
Olympic Flame - yellow and red
Sorbet - red and white
Burning Heart - creamy white and red
Prince Carnival - yellow and red
Beauty of Volendam - Burgundy and white

Fortunately, today's Rembrandt type tulips won't cost you eight fat pigs or a silver drinking cup.

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