Cactus vs Euphorbia (c) Debra Lee Baldwin

Euphorbia or Cactus? How to Tell

How can you tell a spiny euphorbia from a cactus? Evaluate these key characteristics: the type of spines, flowers, and leaves (or lack thereof).

Recently, while compiling my site's new Euphorbia page, I happily acquired the ability to tell at a glance a spiny euphorbia from a cactus.

Milky sap Succulent Euphorbia (c) Debra Lee Baldwin

The defining characteristic of euphorbias is their milky sap.

Sure, you can break a stem, and if it drips milky sap, it's a euphorbia---whether poinsettia, spurge or a succulent tree. But hey! Now you don't have to. Discover the differences here, then take the quiz on my YouTube channel. I promise you'll be delighted at your new knowledge!

Euphorbia vs cactus, fruit & flowers (c) Debra Lee Baldwin

Cactus (left) shows spines, areoles, a pink flower and seed-filled fruit. At right, a euphorbia's flowers are tiny and yellow, and some have formed pods.

Euphorbia or Cactus? Check the flowers and fruit

Euphorbia blooms are tiny relative to the plant. They're most often yellow but may be pale green, cream, pink or red. What looks like petals are actually bracts that surround true flowers.

Succulent euphorbia flowers (c) Debra Lee Baldwin

Euphorbia bracts look like yellow forget-me-nots

Bracts with five rounded petals resemble forget-me-nots, but are waxy and last longer.

Succulent euphorbia fruit seed pods (c) Debra Lee Baldwin

Euphorbia seed pods can be larger and more interesting than the flowers

They're followed by inedible, seed-filled fruit that's knobby, spherical or pumpkin-shaped.

Small cactus in bloom (c) Debra Lee Baldwin

Many small cacti are crowned with vivid flowers in spring

Cactus flowers on the other hand tend to be showy, vividly colored and short-lived (a day or so). Delicate, satiny petals form flowers that look a bit like daisies or water lilies.

Fruit that follows cactus flowers is ovoid and in some species edible. Tiny black seeds dot the flesh.

Euphorbia or Cactus? Examine the spines

How to tell a cactus from a spiny euphorbia

Areoles of cacti (left) are a different tissue from the skin, and spines appear to poke out through it.

A defining characteristic of cacti is that spines emerge from areoles (bumps or tissue) that are different from the skin of the plant. Cactus spines also tend to be needlelike. Although not all cacti have spines (visible ones at least), all cacti have areoles.

Euphorbia thorns

Euphorbia thorns make a V like a snail's head

Euphorbia spines are hard tissue like rose thorns, and often form a V suggestive of cattle horns or a snail's head. (Note: Many succulent euphorbias have no thorns.)

Euphorbia horrida peduncles (c) Debra Lee Baldwin

Dry flower stems (peduncles) cling to the ribs of Euphorbia horrida.

In some Euphorbia species, stems supporting bracts dry and cling to the plant. These "peduncles" may look like spines, but they are not sharp and snap off easily.

Euphorbia or Cactus? Look for leaves

Succulent Euphorbia vs Cactus, leaves

Euphorbia trigona 'Rubra' (left) is fringed with lovely red leaves. Cholla at right has spines for leaves.

Surprisingly, spiny, cactuslike euphorbias produce leaves. If you don't see any, it's because in most species they tend to be insignificant, and they fall off seasonally.

Technically, cacti have "modified leaves:" spines. Stems of cacti may also look like leaves. However, cacti---unlike euphorbias---lack leafy leaves.

Incidentally, cacti are native to the Americas, and succulent euphorbias are from the Old World, mainly Africa. Over the last few centuries, collectors have helped these plants naturalize in warm, dry climates worldwide. But if you’re watching a movie that takes place millennia ago, and Jesus or Alexander the Great strides past a cactus, someone in Hollywood didn’t do their homework.

Learn More and Test Your Knowledge!

Cactus or Euphorbia? video

In this new 8-min. video, discover the differences between cacti and spiny euphorbias, then take the fun and easy quiz at the end. You'll be surprised at how much you've learned!

Comment on YouTube "Cactus or Euphorbia" 20-Question Quiz

Comment on my YouTube "Cactus or Euphorbia" 20-Question Quiz. Yay Alison!

Related info on this site

Spherical succulent Euphorbia meloformis (c) Debra Lee Baldwin

Succulent Euphorbias: Photos, IDs, Garden Uses, Cautions

Euphorbia Uses, Photos and Cautions Native primarily to South Africa, succulent euphorbias thrive outdoors in mild, arid maritime climates. They’re wonderfully sculptural and collectible, but do be careful when handling. See All Succulent Types Aeonium Agaves Aloes Cactus Crassula Echeveria Euphorbias Ice Plants Kalanchoe Portulacaria Senecio About SUCCULENT EUPHORBIAS Euphorbia is a huge genus composed of…

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4 Comments

  1. elspeth flood on March 4, 2021 at 11:24 pm

    You do not mention primitive cactus, which have leaves as well as areoles, and in the case of mine, (name escapes me) beautiful pink flowers like wild roses, which last well. They are not at all hardy, and also dislike getting too wet.
    E Flood.

    • Debra Lee Baldwin on March 5, 2021 at 7:52 am

      Hi Elspeth — There’s always an exception, isn’t there? I should know better than to say “never” or “always.” I believe you’re referring to succulents in the genus Pereskia, which are roselike and have spines which (on close examination) emanate from areoles. Thank you for pointing this out (no pun intended)!

      • Elizabeth Burns on April 24, 2021 at 6:59 pm

        Love your news letters. Is there a succulent that is deer and turkey resistant?

        • Debra Lee Baldwin on April 24, 2021 at 7:50 pm

          Hm. Good question. Deer will eat just about any plants if they’re hungry enough. I’m guessing cacti, euphorbias and large agave species (but not A. attenuata) would not tempt them. As for turkeys…no one has yet to ask me this, so I’m at a loss.

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