Most plants on Earth are genderless. Both the male and female flowers, or parts of the flowers, occur on the same plant. Any plant that exhibits this characteristic is called monoecious, or the more familiar term hermaphroditic. This is a survival mechanism which allows these plants to reproduce with any partner. For some plants, like the rare Euphorbia obesa or ‘baseball plant’, things are a bit more complicated.
Dioecious plants
Dioecious species have separate male and female plants. This means that each plant produces only either male or female reproductive systems. Stamens are the term for male reproductive systems, whereas pistils are the female reproductive systems. The males produce pollen from the stamen, which is then typically taken to a female plant’s pistil by a pollinating insect. The female plant then produces a fruit, which contains seeds. Wind, animals or insect then disperse the seeds, which allows the plant population to grow larger. But how does one identify the difference between a male and female plant, specifically with Euphorbia obesa?
Taking a closer look
This species’ ‘flowers’ stretch the definition of the term. It consists of a small cup-like nub called a cyathium (plural, cyathia) with the reproductive organs on top, and are incredibly difficult to tell apart without practice. The are light green, and have five almost unnoticeable, gland-like ‘petals’. Euphorbia obesa produces flowers throughout spring and summer.
Male Euphorbia obesa flowers
The cyathia of male Euphorbia obesa are a flat-topped cone, with several extremely small flowers on top of it. These flowers are so reduced that they are essentially just a bunch of mini-anthers. They produce pollen, making it the easiest way to identify a male plant. Some pollen may fall of the anthers, so if there is a yellow powdery substance lying on the plant just below the flower, it might be a sign that it is a male.
Male Euphorbia obesa flowers with protruding anthers
Female Euphorbia obesa flowers
In contrast, on female Euphorbia obesa, the cyathia are somewhat easier to distinguish. There is only one flower (and thus one pistil and ovary) per cyathium, with a three-branched stigma extending out of the cone to catch pollen. The individual stigma on females are larger than the anthers on males, and may look somewhat swollen in comparison. They are sticky in appearance, in contrast to the powdery look of the males. This stickiness helps pollen from the male plants attach to the stigma and produce viable seed.
Female Euphorbia obesa flowers with extended stigma
Pollinating Euphorbia obesa flowers
We have noticed that flies tend to hang around flowering Euphorbia obesa, so these may potentially be pollinators of this species. If you do not want to wait for nature to take its course, you can use a fine paintbrush to pollinate. Gently brush the male flowers to collect yellow pollen, then apply it to the female plant.
Once you successfully pollinate a female Euphorbia obesa, it produces three-sided fruit. Rarely, it may produce a four sided fruit. This fruit contains seeds, which can take up to 3-6 weeks to be ready for harvesting, depending on the weather. Remember to cover the top of the plant with something to capture the seeds, as the fruit will burst open once it dries, sending seeds in every possible direction. We use organza bags to cover the seed pods, but it is still not uncommon to find volunteer Euphorbia seedlings popping up in neighbouring plant pots in the Living Desert Plants collection!
A successfully pollinated female Euphorbia obesa producing fruit
Germinating Euphorbia obesa seeds
The seeds themselves are gray or brown. Sometimes, the seeds have a mottled appearance similar to plover eggs. White seeds may also form, but these are not viable and will not germinate.
You do not need to clean Euphorbia obesa seeds before sowing them. While old seed is still viable, we recommend sowing immediately after harvesting, as this seems to increase the chance of germination. Fill a tray with a mix of coco peat, perlite and vermiculite and make sure it is moist. Do not use any hard or gritty substrate like milled bark. The roots of the seedlings cannot penetrate this and will push them out of the soil.
Sow the seeds on top of the soil and cover very lightly with some coco peat It is important not to bury the seeds, otherwise they will struggle to germinate. Cover the tray to increase humidity until at least half the seeds have germinated. We find germination will take place within 7-14 days using this method. However, some seeds may only germinate after 21β28 days.
Like many Euphorbia, the seedlings grow relatively quickly up to 2cm and then slow down drastically. The most vigorous seedlings in our greenhouses produce their first set of flowers after 12 months, but these are generally not viable. You can obtain plants that produce viable flowers and seeds in as little as three years if you handle them correctly.
Want to grow your own Euphorbia obesa succulent?
If you want to add one of these plants to your collection, we can help! Living Desert Plants stocks seed grown Euphorbia obesa, and you can order one by clicking here.
Written by Harry Lewis, succulent specialist & conservationist