Science Questions

How do you age a palm tree because they donít have rings?

Sun, 14th Sep 2008

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Sofia asked:

How do you age a palm tree because they donít have rings?


Kat -  This is a really interesting one and itís very tough to date a palm tree because they donít have rings.  Especially it applies to plants such as cacti and yukkas that donít have that ring structure.  In the case of really old palms you also canít really radio carbon date them.  This works for trees because they have the same consistent heartwood all their lives but this doesnít really happen for palms.  Some botanists use techniques which include counting leaf scars.   Palm trees make new leaves, leaves fall off.  You can count how many scars there are and multiply it by the average time taken to grow new leaves.  Itís not great.  Really the best technique is to look at historical information.  If you can find out when an area was colonised by humans if the treeís not a native species they probably brought it with them.  You can look at old written records, historical records, paintings, photos.  Thereís not really a very good way to age a palm tree.


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Sophia asked the Naked Scientists: Hi, I was just wondering, how would you determine the age of a palm tree if it doesn't have any rings? I have not been wondering about this forever, but it's really bugging me, and you sound like a smart dude. I know how to determine the age of a tree that's got rings, but that's only if it has, well, rings. Please reply soon! -fozzyelf What do you think? Sophia , Thu, 11th Sep 2008

It is very difficult!

Carbon dating can be used on some trees that don't have rings, but palm trees generally can't because there isn't a definable part of their trunk that has been there since the tree's early years (like heartwood).

You can do an age assumption based on the standard (average) growth rate of that variety of palm. These can be highly innacurate, though, since it assumes several things, such as growth being constant over the tree's lifespan.

The only other way is through historical records, like if the tree were in a private garden or somewhere where records of plantings are kept.
Evie, Thu, 11th Sep 2008

Carbon dating only works for ancient wood as it has significant upper and lower limits. Because C14 decay is logarithmic the standard deviation/error factor may be larger than the date obtained. blakestyger, Thu, 11th Sep 2008

Don't they add a certain number of new fronds, on average, per year, so counting the number of stumps where fronds emerged could give a ball-park indication could it not?


P.S. I toyed with the "how do you DATE a palm tree" pun, but abandoned it... chris, Thu, 11th Sep 2008

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