Hubble captures breakup of comet ATLAS

The NASA/ESA Hubble Space Telescope has provided astronomers with the sharpest view yet of the breakup of Comet C/2019 Y4 (ATLAS). The telescope resolved roughly 30 fragments of the fragile comet on 20 April and 25 pieces ...

Tree trunks take a licking as koalas source water

Koalas are one of the world's most charismatic animals. But there is a lot we still don't know about them. For example, how do the marsupials access water in the treetops? Do they only absorb moisture from the gum leaves ...

What's that noise? The 17-year cicadas are back

With warm daytime weather and mild nights upon us, you may find yourself opening a window to enjoy the cool spring air. But accompanying this breeze will be a cacophonous whining like a field of out-of-tune car radios.

Mammoths, mastodons and the fruit they left behind at Fermilab

Scientists at the Department of Energy's Fermi National Accelerator Laboratory are constantly pushing at the boundaries of the unknown in their attempt to understand the origin and physical properties of the universe. Yet ...

Insect virtual reality gives us a fly's perspective of the world

Flying insects are remarkable in their ability to sense and locate food sources and mates as they navigate a complex, 3-D world. Yet, little is known about how they combine different sensory stimuli to find and get to the ...

page 1 from 4


A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to 6 m; some authors set a minimum of 10 cm trunk diameter (30 cm girth). Woody plants that do not meet these definitions by having multiple stems and/or small size, are called shrubs. Compared with most other plants, trees are long-lived, some reaching several thousand years old and growing to up to 115 m (379 ft) high.

Trees are an important component of the natural landscape because of their prevention of erosion and the provision of a weather-sheltered ecosystem in and under their foliage. Trees also play an important role in producing oxygen and reducing carbon dioxide in the atmosphere, as well as moderating ground temperatures. They are also elements in landscaping and agriculture, both for their aesthetic appeal and their orchard crops (such as apples). Wood from trees is a building material, as well as a primary energy source in many developing countries. Trees also play a role in many of the world's mythologies (see trees in mythology).

This text uses material from Wikipedia, licensed under CC BY-SA