How to Sex Your Euphorbia obesa (and why its so hard)

euphorbia obesa

Written ByJen Greene

Posted: June 12, 2024

A super, super, SUPER common question I’ve heard and that our cactus club answers is “how do I know if my Euphorbia obesa is a girl or a boy?”

It’s usually asked immediately after the person has found out that our little baseball plants are generally only one gender; male or female. It’s not that the entire plant is one gender, but rather, that it produces just one gender of flower at a given time.

Or…does it?

First, let’s start with how to identify if your plant is producing male or female flowers. 

Male Euphorbia obesa flowers

male euphorbia obesa

In this hefty bloom of male flowers, you can see a white base at the bottom, and lots of little yellow stamens all over. If you touch them, even just gently, the stamens are likely to fall right off. 

Female Euphorbia obesa flowers

female euphorbia obesa

Here we see several pollinated and unpollinated female flowers. Ther’s a distinct 3-prong antler-shaped part (the stigma) with a single center connection point. You can also see some seeds developing! 

Generally, if you have a plant exhibiting a specific gender of flower, you can expect it to continue to produce that gender of flower.

Try identifying my group of 6 (with a special appearance from one head of my two-headed plant) below:

The answers are…

Right column: all female! Even the one on top, barely visible, you can see reddish colored unfertilized blooms, and a couple of seed pods growing.

Left column: Top is a female, bottom two are male.

If you want to hand pollinate your obesas, or simply let the bees do their work, you need at least one of each gender. The pollen from the males is so sticky and easy to transfer, you can simply use your finger to stick some to it, and then gently apply the stamens to the female flowers.

I also use eyelash applicators to collect and transfer pollen. I find them to be far more effective than a paintbrush, and highly recommend it!

So now that we know male from female, why does it feel like you’re losing your mind when you check the new blooms for the year and find that your labels don’t always match? For me, at least, I had all my plants labeled by gender so I knew I’d have the correct ratio, and I kept finding that despite my efforts, the labels were never 100% right from year to year. 

Was I crazy? Was I just that bad at observation? Did I have too much wine the night I made the labels? Why was this so hard?

Turns out they change sex if they feel like it.

See the thinner obesa in the middle of the top row, between my two fatties?

It’s a male in that photo, which was taken in March of 2024 this year. See below for the zoomed in photo: clearly male flowers that are dying off. 

Same plant, but top right in this photo, taken late May 2024. 


If you look closely at the other male plant in the May photo, you’ll spy a female flower and seed pod growing amongst a group of decidedly male blooms. 

So if you’re ever unsure if you’re accurately identifying if your Euphorbia obesa plants are male or female, and you feel like they’re playing tricks on you… they are. 

Don’t sweat it. Just buy a few more. 

Then hope they don’t all decide to become female like mine. *sob* 

Maybe I’ll get more boys next season…

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