Extra. Unit 4. Welwitschia. One Ugly Plant?

One Ugly Plant!

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. It has some Gymnosperm characters shared with conifers like Pinus and Thuja, but some Angiosperm characters – like wood vessels in the secondary xylem – as well. Welwitschia is not only pollinated by wind (like the gymnosperms) but also by insects. Both the female and male flowers produce nectar; the male flowers produce small quantities of pollen. Both characters are typical of insect-pollinated angiosperms . The male flowers are similar to some Angiosperm flowers . Pictures

Vocabulary

• 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.

Activity

1. What makes this plant so weird, peculiar, wonderful, strange, bizarre, fascinating, misterious, and of course, unique? (list all the facts)
   
2. What characteristics does it share with gymnosperms and what treats are of angyomsperms?
   
3. The Welwitschia mirabilis has attracted a lot of attention from botanists since it was discovered in 1863. Why do you think scientists study plants? What potential benefit might there be in studying a plant that has developed the ability to live for so long in a harsh climate? Write a paragraph explaining your opinion.

http://www.eduplace.com/kids/hmsc/5/a/cricket/cktcontent_5a2.shtml
http://www.interhomeopathy.org/welwitschia-mirabilis-duality-and-transformation