One Ugly Plant!
by Jane Scherer
What do actor Tom Cruise and the desert plant Welwitschia mirabilis have in common? Well, one thing's for certain. . .it isn't good looks. Remember the greenhouse scene in the movie Minority Report? Yep, that wasn't a creeping spider or a pile of trash behind the star. It was Welwitschia, one of the ugliest plants alive!
“It is without question the most wonderful plant ever brought to this country, and one of the ugliest,” said the Keeper of the Royal Botanic Gardens in England in 1863 when he was given a specimen. Today, botanic gardens around the world grow Welwitschia, but they are infants compared to the ancient ones growing in the wild.
Welwitschias live in the coastal desert regions of Namibia and Angola, Africa. They get the moisture they need to survive from fog rolling in from the ocean. Carbon-14 dating has placed the age of two of the plants at 1,500-years-plus!
“It's a fascinating plant because it is so bizarre,” says Judy Jernstedt, a plant morphologist at the University of California who has traveled halfway around the world to see them. “Basically, Welwitschia has only two ratty-looking leaves that last hundreds if not thousands of years.”
The stem of an adult plant is a look-alike for an upside-down traffic cone. From it, two long, straplike leaves grow and grow and never fall off. As the centuries pass, the desert winds whip, shred, and tangle them into a shoulder-high mass of twisted ribbons. An African name for the plant says it all: “long-haired thing.” Named after Friedrich Welwitsch, the explorer, Welwitschia, bears small cones instead of flowers. Its male and female organs are separated. Where in the scheme of plants does it belong?
And there is another mystery. Desert plants grow with little or no water. They can't seal their tissues completely to hold what little there is, because they need to take in carbon dioxide for photosynthesis. As a result, most have no leaves, or tiny ones. Welwitschia's leaves spread a quarter of a meter and release a liter of water a day! Botanists think it must come from the plant's collection of soil moisture.
A female plant produces some 20,000 seeds each year. In a greenhouse they germinate freely, but in the desert 90 percent of them mold. The 10 percent that survive send down long taproots in just a few weeks.
“Welwitschia combines some traits of gymnosperms such as conifers and also traits of flowering plants, but it still isn't clear to plant biologists exactly where it fits into the emerging picture of plant evolution,” says Jernstedt.
- carbon-14 dating: Determining the age of an ancient specimen by the amount of carbon-14 it contains.
- morphologist: A biologist who deals with the form and the structure of organisms, without consideration of function.
- Some Welwitchia mirabilis plants are female, and others are male. The female plants produce seed cones, and the male plants produce cones that flower. The flowers contain pollen. Why do these characteristics make it difficult to classify the Welwitchia mirabilis? Write a few sentences in answer to these questions.
[anno: The plant is difficult to classify because it produces both cones, like a gymnosperm, and flowers, like an angiosperm.]
- How do you think the Welwitchia mirabilis reproduces?
[anno: Answers will vary but could include that wind or insects carry pollen from the male plant to the female plant. When a seed has been fertilized inside a cone, the cone opens and releases the seeds.]
- What advantages do you think there are to a plant species that produces male and female plants? Write a few sentences to explain your answer.
[anno: Answers will vary but could include that if a species produces male and female plants the species might be more likely to survive if a change occurs in the climate or weather conditions.]