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I just bought a Pink Delight Dragon Fruit. I noticed that all of the cacti at the store had joints, dried flesh that tapers to small point. They seem like a weak point to me, a brittle point that can snap off. How are these joints formed, what purpose do they serve, and should they be prevented?

The joint is illustrated in the lower right of this photo. It is the tan portion on the right stalk. It looks as if it was severed at that point, but it's obviously not because the upper portion of the stalk is still green.

enter image description here

JoJo
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    Ask the Cholla, they're propagation packages. You get tangled, it breaks off, you figure out how to remove it and toss it aside. Whoops, there's another fine entanglement trap waiting for the next victim. – Fiasco Labs May 12 '14 at 23:25

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Plants grow in different patterns... most of a plant can't grow like an animal, because of the physiology of the cell, plants (with very few exceptions) have cell walls made of cellulose... so it is useful to think of an adult plant cell as a brick... and you can't easily expand a brick structure from the middle.

so plants grow in small regions call "meristems" these are the only places that a plant can grow... and basically any place you see a plant growing (not just expanding) is a meristem. the tips of the roots, buds, and the special meristem that is the main growth bud of a plant is called an "apical meristem"... so that is the background.

Cactii only have a couple of growth patterns, a few like Organ Pipe, and Saguaro, and Barrel Cacti have a main meristem that just keeps growing indeterminately, but many, like Cholla, Easter Cactus, Christmas Cactus, and Prickly Pears will grow to some predetermined size then stop, and for further growth to occur it has to bud and create a new growth area.

This is just how they are, some cactus use this to spread, they can break off and become a new plant where they fall, others just grow this way to accommodate seasonal growth...

Grady Player
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That is handling damage. The stem was cut into some time ago. You can try to avoid damaged plants while shopping, and avoid further damage by careful handling. Your plant doesn't look too bad. It should grow just as well as another one, but again, try to avoid rough handling.

J. Musser
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  • But I see these joints appear on dragon fruit in professional farms as well. [See this photo](http://2.bp.blogspot.com/-md20Pyn1v1k/UfkMW3kXj8I/AAAAAAAAAJE/D6cZsZN07Gs/s1600/refmad-farms-dragon-fruit-farm.jpg). The professionals also damaged their plants? – JoJo May 16 '14 at 15:28
  • @JoJo Damage is almost inevitable on a large-scale operation. It's really not a big deal. – J. Musser May 18 '14 at 02:24