Do Cactus Spines Grow Back? [Tested With Timelapse]

Ever happened to break your beloved cactus spines. Yes, quite a few times. Are they going to grow back? I tested and documented an experiment about broken cactus spines that will fascinate you.

Spines arise from the areoles of the cactus. If a spine is broken, it will not regrow. However, if the broken spine was in an areole near the apex of the stem, then, new spines will very likely grow as “replacement” in 1 to 2 weeks depending on the species. If the spine is broken in another part of the cactus, not the apex, it will not be replaced.

Cactus spines certainly have a purpose in the growth of the plant. But how about if they are cut off, will there be a chance of regrowth? Read further and find out the exciting characteristics of cactus spines.

Does A Broken Cactus Spine Regrow?

Spines that are cut or removed will not grow again. However, new spines may grow from almost in the same spot, on the existing areole, near its apex. The growth process usually takes at least a week.

A broken or pulled-out cactus spine will not regrow on the exact spot on the areole where it is removed. But, fresh new spines will develop on the same areole just a few millimeters away. Moreover, if you break in half a 2 cm spine of a Golden Barrel cactus, don’t anticipate it to generate.

This is a Gymnocalycium used in the experiment. The damaged spine did not grow back, but a new spine developed right on the same areole.

The tissues of matured spines are totally dead. That is why broken or damaged needles are permanent and will not be replaced. Granted that a cactus is healthy and actively growing, it will continue developing new areoles and growing spines.

What Are Spines, Areoles, and Apical Meristem?

Before going on, let us familiarize some terms for better understanding.

  • Cactus Spinesare reduced leaves growing on the areoles of the cactus stem. They consist of fibers enclosed by a special type of cells that make them rigid. As they mature, their cells die, and they stop growing. However, young spines that are actively growing have living cells at their base that keep pushing the spine up over time.
  • Areoles – are bumps of living cells and are referred to as specialized structures of a modified branch in a cactus stem that sets off spines, pups, and flowers. Areoles are the distinguishing characteristic of cacti among plants that have spines and thorns. For a plant to be called a cactus, it should have an areole.
  • Shoot Apical Meristem – is the region where meristem cells are located. These special cells promote the growth of organs and tissues in the plant. In cacti, these growth cells are found on the apex of their stem.

Cactus Spines Experiment

An experiment was set out to test if cacti spines will still grow on the same spot after being cut or will another new spine develop.

Samples Used

A test sample and a reference sample of the same cacti species were provided for the experiment. Overall, we have tested two different varieties of cactus and observed how they react to the experiment.

1 pair of Gymnocalycium mihanovichii – 2-3 spines growing on an areole- young spines are white with a brown tip and erected
– matured spines are wholly brown and slightly curled 1-2 mm long
1 pair of Echinopsis Arachnacantha– 9-15 spines growing on an areole
– new spines are reddish
– matured spines are brownish-white 5mm long
Echinopsis Specimen
Gymnocalycium Specimen

Procedure

The spines of the test samples were cut off using a nail clipper, and some areoles were purposely damaged to test if they would regrow spines. For the reference sample, the spines and areoles remain intact for comparison. All specimens received the same amount of sunlight and water.

Test samples after spine removal.

Experimental Results: Cactus Spine Regrowth

Three short white spines begin to grow on the areoles of the Gymnocalycium’s apex center six days after the spines were cut. But the Echinopsis start growing four sharp red tip spines one areole away from the center seven days after. They are not the same spine that was cut.

I observed that the Gymnocalycium sample was the first to develop noticeable new spines from the areoles near the apical meristem. While the Echinopsis spines became evident one day later, the plant formed more needles. The spine didn’t grow back from the same spot as the broken one.

New spines become evident 6 and 7 days after.
Gymnocalycium has regrown more spines than Echinopsis after 2 months.

Most spines grow only on the active areoles at the growth point of the cactus. Areoles away from the apical meristem did not grow new spines within the duration of the experiment (2 months).

Is It Bad For Cacti To Lose Its Spines?

Spines play a significant role in cacti’s growth, especially those growing in the wild. When cacti lose spines, it will place the plant at a disadvantage that can cost its survival. However, indoor cacti will not suffer seriously from the loss of spines if not for a higher incidence of sunburn.

Cacti in nature depend on their spines for several reasons. It has a lot of functions on protecting and gathering resources for the plant. Below are the possible drawbacks if the cactus loss its spines.

The 3 main problems in cacti without spines are 1) higher incidence of sun damage, 2) higher water loss, and 3) risk of predation.

1- Sun Damage

Cactus growing in extremely sunny and hot areas benefit from their dense spines for shelter against the scorching sun. Thickly spiny cacti will get sunburn in areas with damaged spines. This is why cacti that have no or fewer spines are more prone to getting sunburn.

The risk of spine loss in cactus

2- Water Loss

Without the spines that shade the plant, the heat of sun rays quickly reaches the cactus’s surface, where water is stored. There will be rapid evaporation of water from the stem, and the plant will suffer from dehydration. They cannot withstand a long period of drought and they will tend to wrinkle.

Spines don’t retain water, but they contribute to the collection of water from rain and vapor. Moisture is trapped in the spines, runs down onto the stem and soil, and is absorbed by the roots.

3- Risk of Predation

Outdoor cactus are vulnerable to hungry herbivores without their spines. The sharp and solid spines are their defense against predators that love to munch on their succulent stems. Dears, rabbits, and other wildlife animals can easily devour areas that have no spines.

How To Avoid Cactus Spine Damage – Infographic

How To Avoid Spine Damage?

Moving and repotting cacti are the common scenarios that may damage their spines. Here is how I reduced those unwanted accidents over the years.

  • Use leather gloves or a thick towel when repotting huge cacti. Repotting cactus with heavy spines is challenging and dangerous. It’s either you’ll get hurt, or your cactus will get damaged. It is best to use durable gloves and thick rugs to get a good grip on your cactus without breaking it and won’t put you in danger as well.
  • Use silicone tongs or rubber gloves when repotting small cactus. Small cactus spines may tend to break easily. Carefully handle your small cacti when repotting by using soft tongs and gloves.
  • Loosen the roots first when uprooting. Pulling the cactus out from the pot without loosening the soil will tend to damage the spines. It is best to loosen the soil before uprooting, so you don’t have to grip the cactus stem firmly and break the spines.

Here below are some good tools for repotting.

Does a Damage Areole Grow Spines?

Once an areole is heavily damaged or removed, it cannot produce new spines or offsets.

Removing a portion of stem rot or infection from a cactus can damage areoles permanently. Animal bites, extreme sunburn, and severe insect infestation can destroy areoles as well.

Damaged areole do not have spines, while the healthy areole has healthy spines.

Takeaways

  1. The broken cactus spines will remain broken and will not regrow, but new spines can form again as long as the cactus is healthy and grows actively.
  2. Spines develop on the bumps of living tissues called areoles of a cactus. When the areoles are damaged, they will stop producing spines.
  3. Cactus with damaged spines and areoles are prone to sun damage, water loss, and predation risk.

Sources

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