Precautionary warning on plant produced oxalates


Oxalates? Better safe than sorry

Oxalates - definition

An oxalate is a chemical compound that contains the oxalate ion (C2O4^2-). It is formed when oxalic acid, naturally occurring in plants, reacts with a metal element like calcium (or natrium etc.), forming insoluble crystals known as oxalates.

Calcium oxalate crystals appearance

They form either octahedral (tetragonal) or filamentous (monoclinic) needle-sharp transparent microscopic (5-100μm) crystals sometimes aggregating into bundles, s.c. raphids.

When do calcium oxalate crystals form?

Calcium oxalate crystals can form in various situations, including:

1. Kidney Stones:

In animals (including humans), high levels of oxalates in the urine can combine with calcium to form crystals that can accumulate and grow into kidney stones, causing pain and blockages in the urinary tract.

2. Plant Tissues: Oxalates are also found in plant tissues, particularly in certain parts like leaves, stems, and roots, acting as a defense mechanism against herbivores by forming sharp crystals that can deter or injure animals that try to eat them.

3. Food: Some foods containing oxalate-rich plants, can promote the formation of crystals

How oxalates may harm:

1. Biochemistry: calcium. Formation of calcium oxalate. High levels of oxalates can bind with calcium, forming insoluble crystals that can hinder calcium absorption, leading to MBD, hypocalcemia, weak nails, weak egg shells and bones, weak offspring, defects in neurotransmitter release and muscle contractions, relaxation of heart muscle, inhibition of the calcium pump, cardiac arrest, seizures.

2. Biochemistry: enzymes. The calcium oxalate cause the proteolytic enzymes to trigger the release of potent kinnins (in some cases, causing edema) and histamines.

3. Mechanical constraints - Kidneys: Calcium oxalate crystals can accumulate in the kidneys, leading to the formation of kidney stones, causing pain, urinary tract blockage, and potential renal failure.

4. Mechanical constraints - oral cavity, digestive tract: sharp oxalate crystals can irritate the soft tissues in oral cavity and digestive tract, or can even penetrate internal organs, cause swellings, pain, discomfort, stress, micro injuries that can get attacked by bacteria and cause inflammations, abscesses, mouth-rot, abscesses etc.

1. Mechanical constraints - skin and eyes: oxalate crystals contained in high concentration in some plants like Hedera (poison ivy) or Dieffenbachia (dumb cane) can cause skin irritations even when touched or rubbed. They can cause hard to heal eye irritations which are not diagnosable, or they can penetrate the skin, especially of soles and cause skin irritations, swellings, micro traumatic inflammations to non healable skin lesions.

Important notes:

1. It's important to note that not always and not all oxalates form crystals, their formation is dependent on factors like concentration, presence of calcium or other minerals, and the pH.

2. Oxalates are known to have an influence on mammals and also reptiles (less studied), particularly in their diet. Different reptile species may have varying tolerances to oxalates: some reptiles, like tortoises and iguanas, have evolved to process and eliminate oxalates more efficiently than others.

3. Oxalates and their effects on chameleons specifically have not been studied rigorously yet. Obviously, they make profit of the general higher tolerance to oxalates of reptiles if compared to mammals. The contradictions are unresolved: at one side, oxalates are suspect to cause renal failures and calcium metabolism failures as well as deaths of chameleon babies if exposed to them, on the other side, the longevity records of Chamaeleo calyptratus recorded were associated with oxalates-rich plants eaten by them on a regular basis,

4. Moreover they were reported to munch in the wild on Sansevieria too.

Therefore: better (super)safe than sorry - better prevent any contact of the chameleons with the dangerous plants full of oxalates

Measures to be taken:

1. Never feed chameleons with ANY plant matter

2. Never gutload insects with oxalate-rich plants

3. Dispose any oxalate-rich plants from the cage to exclude the possibility that feeders feed on them and are afterwards eaten by the chameleons

4. Dispose any oxalate rich plant from the cage to exclude any poisoning of chameleons, be it incidental ingestion or touching

Plants ad 1&2


Beet greens



Navy bean







Plants ad 1,2,3&4

Calla Lily (Zantedeschia aethiopica)

Devil's Ivy (Epipremnum aureum)

Poison Ivy (Toxicodendron sp.)

Common ivy (Hedera helix)

Dumb Cane (Dieffenbachia sp.)

Elephant's Ear (Colocasia sp., Caladium sp.)

Jack-in-the-Pulpit (Arisaema triphyllum)

Mother-in-Law's Tongue (Sansevieria sp.)

Heartleaf (Philodendron sp.)

Peace Lily (Spathiphyllum sp.)

Inch plant (Tradescantia sp.)

Author: Petr Nečas