It’s not unusual for tiny leaves to grow on young cacti but as your cactus ages, the leaves drop off and don’t come back.
If you have an older plant that you’ve identified as a cactus and it’s growing large leaves; the chances are it’s not a cactus – it’s some species of euphorbia.
Euphorbia is not actually a single plant, it’s a genus of plants that consists of more than 2,000 species.
Euphorbias are often mistaken for cacti because they both have prickles.
But they don’t have the same type of prickles.
Cacti have spines and euphorbia have thorns.
Because cacti have evolved to thrive in hot, dry climates, they are lacking traditional leaves and have evolved spines instead.
These spines have evolved from leaves for the purpose of shading the cactus, protecting it from animals, and preventing it from losing water through evaporation.
The spines come from areoles, which all cacti have.
Euphorbias usually have thorns that grow together in pairs.
These thorns are modified stems because euphorbias don’t have areoles and that’s one of the main things that differentiates them from cacti.
Another thing that makes euphorbias different from cacti is their ability to grow large leaves.
The leaves on your euphorbia are nothing to worry about and just mean that your plant is growing.
There’s no harm in plucking them off if you’re not a fan of how they make your plant look but after a while, the leaves will usually fall off by themselves.
Euphorbias are usually poisonous.
Also be aware that euphorbia plants produce a white, latex sap that has varying levels of toxicity to people and pets.
Because of this, when pruning or taking cuttings from these plants, it’s advisable to wear gloves and to be extremely careful not to ingest the sap, or get it in your eyes or on your skin.
So, if you have a large adult plant that you believe to be a cactus and it is growing large leaves, then you most likely have a species of the euphorbia genus plant and not a cactus.