Paleobotanist Jack A. Wolfe of the United States Geological Survey at Menlo Park, California, has found a number of tropical rain forest fossils along the eastern Gulf of Alaska. These include several kinds of palms, Burmese lacquer trees, mangroves and trees of the type that now produce nutmeg and Macassar oil.
Updated For decades, the city's forestry workers battled Dutch elm disease with projects to spraying healthy trees and removing dead or diseased trees. The ...
The American elm (Ulmus americana) was once a common sight on the Upper Mississippi River, but Dutch elm disease, or DED, has killed many trees. DED is an invasive fungal pathogen that is spread by ...
The Klukwan giant belies the belief that trees tend to get smaller the farther north one goes. Both balsam poplar and cottonwood have value for fuel wood, pulp and lumber.
These trees are now responding to fewer hours of sunlight by ceasing to flood their leaves with chlorophyll. The sudden lack of that green, energy-converting chemical allows the leaves to show red, orange and yellow pigments that were within the leaves all summer.
By late winter, intricate buildups of hoarfrost crystals have formed on wooden poles and other objects. Warming rays of the sun cause evaporation of whatever frost may have formed on the south side of vertical poles and trees. Conduction within metal poles causes enough heat transfer to entirely remove the hoarfrost crystals from the pole surface.
The elderly trees still produced seeds, but none of the seeds gerrninated, even when carefully tended under ideal nursery conditions. It was tempting to think the old trees were incapable of producing healthy seeds, but Temple didn't accept that reasoning. For one thing, the seeds (and their encasing fruit) looked fine.