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Opuntia, prickly pear cactus, is a hardy plant with a wide range of distribution. Its growth habit is by branching paddles, or nopales.

Is there any way to measure or estimate the age of such a cactus? By age, I think I mean the time elapsed since the specimen was cloned, or the age of the roots.

Opuntia in the wild

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    No. They can put out more than one pad per year, or less, depending on conditions, and sometimes the lower portions on the creeping types eventually decompose as the plant grows and roots from new pads. But do you have a particular specemin in mind? – J. Musser Mar 31 '17 at 3:55
  • @J.Musser thank you. Yes, there is a particular gnarled one I'm curious about near the home site in Wilder Ranch State Park. – Aaron Brick Apr 11 '17 at 17:53
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Your question on how to estimate the age of Opuntia cactus was quite intriguing to me, after some weekend research the following study seemed most appropriate:

Growth Rate and Life Span of a Prickly Pear Cactus, Opuntia engelmannii, in the Northern Sonoran Desert Author(s): Janice E. Bowers Source: The Southwestern Naturalist, Vol. 41, No. 3 (Sep., 1996), pp. 315-318 Published by: Southwestern Association of Naturalists Stable URL: http://www.jstor.org/stable/30055130 Accessed: 08-08-2017 14:44 UTC

They set some qualifiers for a couple of score cacti to study, which primarily included the following:

  • Origin of the plant was apparent; the plant was not so old that its original plant parts had rotted away.
  • The plant had no apparent rotting, disease damage, or other obvious issues that would reduce its size or slow its growth rate. There was no apparent evidence of infestation, or animals using the cactus plants as a home or den.

The study found did produce a formula for estimating the age of a plant based on the number of cladodes it had, and this formula seems to relate to other areas in the southwestern USA, and across other species of Opuntia. There is an average 20% loss rate of cladodes each year. I encourage you to read the 4-page article, see link in source reference above.

The following graph is the simplest way to gauge an Opuntia cactus' age:

enter image description here

Finally, the Opuntia you have pictured is relatively old and without some pictures of the base and poking around in the dirt around the roots it's my best guess is it is over 2, perhaps 3 decades old.

  • Very interesting. Seems they have trouble reaching 25 years of age without one of the disqualifying events happening. – Aaron Brick Aug 9 '17 at 4:18

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