Ever green: Pine trees, which can grow for thousands of years, are the oldest living trees. But scientists are learning that palms can be even older—at least at the cellular level. A recent American Journal of Botany paper explains that conventional trees experience a secondary growth phase—replacing functional tissues with younger cells—but palm trees do not. The individual cells in a palm, seen in this micrograph of the genus Veitchia, endure throughout the tree's life span, which can range from 100 to 740 years.

This 1.5-millimeter-wide cross section of a vascular bundle (green and red center) is responsible for transporting water, minerals and nutrients through the trunk. Thousands of these bundles are found in every level of the palm and continuously work to sustain its growth.

This article was originally published with the title What Is It?.

5 Comments

1. 1. jogolden 06:10 PM 3/9/13

   Palm "trees" are monocots, and as such, are not trees! They're woody grasses.

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2. 2. frankblank 12:12 AM 3/10/13

   Well, they're not as old but older at the cellular level? Science attains Romney Speak.

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3. 3. thevillagegeek 12:48 AM 3/10/13

   What, no 'oldest living fossil' quips?

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4. 4. scribblerlarry 09:14 AM 3/10/13

   I have to agree with "jogolden". Palm trees are indeed grasses.
   
   Poor ol' Scientific AMERICAN; wrong again. That's what you get for publishing articles written by non-scientist staff and contributors.
   
   Yeah. I know. Real AMERICAN publishers are more interested in selling more copies of the publication with attention-getting trash, than in accuracy. This publication has become a joke!
   
   ;-)

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5. 5. SayblFox in reply to jogolden 04:03 AM 3/11/13

   "Trees" don't make up a monophyletic evolutionary group, nor is "tree" a scientifically rigorous technical term. Conifers are mostly considered trees, and besides them countless plants clearly considered trees are angiosperms. Just within the angiosperm family some trees are monocots, some are dicots, either subgroup more closely related to the other than either are to conifers. And yes, some plants considered trees, like palm trees, and occasionally bamboo, are grasses. Tree is just a word for a largish plant with a generally tall, often woody trunk.

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