in the news archives unit 5 ('98)

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EARLY FLOWERING PLANT REDISCOVERED AFTER 85 YEARS

In June 1997, botanist Armen Takhtajan received a plant for his 87th birthday. This was no ordinary plant, however. Discovered in 1909 on Madagascar and named after the Russian botanist in 1963, Takhtajania perrieri was known only as a dried specimen in a Paris museum. Despite years of searching, the elusive flowering plant was not found in the wild again until May 1994. The history of its discovery, however, is not as fascinating as the plant's natural history--T. perrieri is probably one of the earliest flowering plant species still alive.
An expedition from the Missouri Botanical Garden (MBG) collected new specimens of the plant in June 1997, sending samples to laboratories all over the world. Preliminary sequencing of the species' DNA places it as the oldest member of the Winteraceae family. This tropical plant family is common in the Pacific and in Central and in South America, but was believed to have died out in Africa 30 million years ago. Winteraceae is one of the oldest flowering plant families still in existence, meaning that T. perrieri comes from a very old line indeed.
Its physical structure also reveals its ancient heritage: T. perrieri lacks vessel elements, a type of water-conducting cell found in most flowering plants. T. perrieri relies on more primitive and less efficient tracheids to conduct water. Without the efficient combinations of vessel elements and tracheids that most flowering plants possess, T. perrieri is confined to wet habitats. Analysis of the DNA of T. perrieri and of other flowering plants should make the story of angiosperm evolution more clear.
Here are some additional sources of information:
A special report from MBG on T. perrieri, showing photos of the plant and where it was found
An article on T. perrieri and its rediscovery on Madagascar
A photo essay on the plants, animals, and people of Madagascar, from MBG
Other research the Missouri Botanical Garden is conducting in Africa

FIR AND BIRCH TREES SHARE CARBON THROUGH UNDERGROUND NETWORK

Biologists have long known that certain fungi and trees share a special bond. The fungus forms a web-like association with the tree's roots called mycorrhizae, supplying the trees with nitrogen and phosphorous. In return, the trees provide the fungus with carbohydrates, manufactured from carbon dioxide during photosynthesis. What scientists recently discovered is that the mycorrhizal fungi can transfer this carbon from one tree to another, sometimes even to another species of tree.
In an article published in the August 7, 1997 issue of Nature, Suzanne Simard and her colleagues describe how they planted fir, birch, and cedar seedlings together in groups. They gave carbon dioxide labeled with one isotope of carbon to the firs, while giving carbon dioxide labeled with a different isotope to the birches. Two years later, they found that the fir and birch had exchanged carbon through the fungal network, but cedar, which does not associate with the same type of fungus as birch and fir, did not. However, the fir seedlings were slightly more efficient at pulling carbon from the network, with about 6 percent of their carbon labeled with the isotope given to the birches. The researchers also found that the firs in the shade took up to 10 percent of their carbon from the birch seedlings, much more than the firs in the sun.
The differnce in carbon uptake by sunlit and shaded firs indicates that trees take up sugars from the fungal network according to their needs. The researchers can't yet explain what benefit the fungus receives in return for giving up its carbon to a second tree, except that it benefits the community as a whole. This discovery will likely change the way ecologists think of interspecies tree interactions, which were previously thought to be purely competitive.
Here are some additional sources of information:
An article describing this research
The British Columbia Ministry of Forests, where Suzanne Simard works

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