Madagascar Jewel: The Pass-Along Succulent

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Madagascar jewel (Euphorbia leuconeura). Photo: plantsam.com

You’ve never heard of the Madagascar jewel (Euphorbia leuconeura)? I’m not surprised. It’s a fairly obscure houseplant, certainly not one you see often in garden centers. However, it is making the rounds in a parallel system … as a pass-along plant. A neighbor, friend or relative gives you one, then you grow it and produce baby plants that you give to someone else. And it’s been spreading that way for years, as I can recall first seeing it about at a plant exchange about 30 years ago.

How do I know that this plant is so widely grown? People keep sending me photos with the question, “What is this plant?” Or they bring a specimen or cutting to a lecture I’m giving and ask if I know it. It’s instantly recognizable. 

There really isn’t anything jewellike about a mature Madagscar jewel, here one with several branches. Photo: Tommy Kronkvist, Wikimedia Commons

Oddly, I didn’t even know this plant had a common name under I decided to research this article. I’d always known it simply as Euphorbia leuconeura, which would translate as white-nerved euphorbia. The name Madagascar jewel is rather a silly one, actually. Yes, it does come from Madagascar, but I fail to anything jewellike about it. A jewellike plant would be small and kinda cute, don’t you think? But Madagascar jewel is big and rather thuggish.

Background

E. leuconeura is a succulent shrub, even a small tree, reaching to 1.8 m (6 ft) in height. Although commonly mistaken for a cactus, it’s actually a member of the euphorbia family (Euphorbiaceae).

Juvenile plant with white nerves. Photo: http://www.kakteen-matk-berlin.de

Young plants bear tear-shaped leaves with brilliant white nerves and a reddish petiole. The white coloration fades over time and the nerves become green. The petioles, though, retain their reddish tinge, most visible in strong light. Mature leaves are dark green and leathery, measuring up to 15 cm (6 inches) long and 6.5 cm (2 ½ in) wide. They too sometimes have a reddish tinge, especially if you grow the plant in bright light.

Over time, the stem thickens and becomes angular. Photo: Reda Tomingas, Flickr

On young plants, the stem is tubular and green or reddish, but soon thickens and then develops 4 to 5 distinct angles with brown hairy edges. It remains green with pale brown crescent-shaped marks where old leaves were once attached. The stem grows straight up at first, only branching after several years or if pruned.

The flowers aren’t too impressive: you have to get in close to even notice them. Photo: Baja-Costero, garden.org

After a year or so, the plant begins producing abundant clusters of tiny insignificant white flowers without any petals at the axils of the upper leaves. They’re not attractive, but soon produce seed capsules that open explosively, shooting seeds up to 2 m (7 feet) away. The seeds germinate readily and soon baby plants begin popping up in the pots of all the houseplants nearby, even in the garden if the plant is outdoors for the summer. If you don’t want the plant to self-sow, pinch off the seed capsules.

E. leuconeura is apparently endangered in the wild, although hardly so in culture!

Growing Your Own Madagascar Jewel

This is a widely adapted plant, easy to grow indoors. 

It prefers bright light to full sun, but will tolerate shade. Under low light, expect the plant to be floppy and requite staking. 

Young specimens of Euphorbia leuconeura. Photo: http://www.instawas.com

Although this plant is a succulent and tolerant of dry soils, it doesn’t seem to mind regular watering either. In fact, plants grown too dry will lose more of their lower leaves (sometimes even all of their leaves) and will be less attractive than specimens grown in soil that is kept slightly moist. Just follow the golden rule of watering: water deeply, enough to moisten the entire root ball, then allow the soil to dry before watering again.

What Madagascar jewel doesn’t like are cold temperatures, below 10˚C (50˚F). In fact, keep it above 15˚C (60˚F) at all times if at all possible. 

You can grow it in just about any potting mix: either a regular houseplant blend or cactus and succulent mix. You’ll probably need to repot young plants annually into larger and larger pots. Use heavy pots for big specimens, as they become top-heavy.

Fertilize your Madagascar jewel if you want, using the fertilizer of your choice, but do so lightly and during the main growing season only (spring through early fall). It will also get along fine without any fertilizer.

It’s perfectly happy with dry indoor air, so there is no need to increase the atmospheric humidity. It will, however, readily tolerate the higher humidity most other houseplants need.

Seedlings sprout pretty much everywhere. Photo: growandcare.com

As for multiplication, it usually does that on its own, seeding itself about not only in its own pot, but in those of other plants. Baby plants thus produced can then be potted up separately. You can also catch the seeds (try bagging the plant with an organza sack) and sow them, barely covering them with potting mix. They germinate in about a month at warm temperatures (22 to 25˚C/72 to 77˚F). You can also take cuttings if for some strange reason you need even more plants.

When pruning, wear googles and protective gloves, as the milky white sap is irritating and toxic. If you get any on your skin, simply wash it off. Keep this plant out of reach of children and pets. 

If your plant is so tall it needs staking, it’s probably best to start a new one. Photo: MiniHamster5, reddit.com

Honestly, the best way of growing this plant, which gets big and ungainly over time, is to get rid of mature specimens when they take up too much space and simply replace them with one of the abundant young ones that appear everywhere.

I would not recommend growing this plant outdoors in a tropical climate (it is only hardy to USDA zones 10 and above and prefers arid to semi-arid conditions). It’s far too invasive!

Where to Find Plants 

A lot of nurseries won’t grow Madagascar Jewel, considering it too weedy, but you can find plants and seeds online not only from specialist succulent nurseries, but also from such providers as eBay and Etsy.

And, of course, you can easily find specimens at plant exchanges, in flea markets or through your local garden club. Just show a photo at any plant meeting (no use comes from asking for this plant by either its common name or botanical one: few owners know  either!) and hands will rise. Yes, for an obscure plant, Madagascar jewel is actually amazingly common.

Houseplant Weeds

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Kalanchoes (here K. daigremontiana) readily invade neighbouring pots and can be quite the pests!

You thought that by moving indoors to garden you were leaving the world of weeding behind? Well, think again. Like the weeds of our gardens and lawns, there are both weedy houseplants and houseplant weeds, plants that ready spread from pot to pot, seeking to take over the main plant’s space. And they really aren’t that rare. If you grow houseplants, you probably already know some of these plants already.

Guilty Parties

Here are a few of the plants that are often weeds indoors.

Kalanchoe

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Baby plants crowd the kalanchoe’s leaf margin and readily come free.

Several kalanchoes (Kalanchoe daigremontiana, K. pinnata, K. laetivirens, etc.), all once formerly included in the genus Bryophyllum, have the curious habit of producing plantlets along the edge of their leaves. That is just soooo cute! And it gives you plenty of babies to share with your friends… but the babies readily “jump” into the neighboring pots and set up shop. They don’t actually jump, of course, but fall or get knocked free. Even so, when the pot next store fills up with the no-longer-quite-so-cute adolescent kalanchoes, there will be quite a bit of weeding to do.

Worse yet, kalanchoes are allelopathic: that is, they release toxic products that harm the plants whose pot they share. Thus, the desired plant grows less vigorously or may even die.

It’s better to put “jumping kalanchoes” in their place and not let them spread around indiscriminately!

Purple Shrimp Plant

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Purple shrimp plant (Porphyrocoma pohliana)

This is a charming little houseplant in the Acanthaceae family with an as yet unresolved botanical name (Porphyrocoma pohliana and Justicia scheidweileri are on the short list). It’s certainly pretty enough, with shiny leaves highlighted by silver veins and a long-lasting red “cone” at its top from which the more ephemeral purple flowers appear.

This one just showed up in my plant collection one day, undoubtedly having hitched a ride in another plant’s pot. Now I find it all over the place.

Polka Dot Plant

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Polka dot plant (Hypestes phyllostachya)

The polka dot plant or freckle face plant (Hypoestes phyllostachya), likewise in the Acanthaceae family, is a low-growing mound-forming plant with leaves dotted with spots and splotches in white, red or pink, sometimes to the point where there is little green visible, and likewise self-sows. The inconspicuous flowers often go sight unseen, but the baby plants that pop up here and there are much more readily visible.

Spider Plant

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Flowers of the spider plant (Chlorophytum comosum)

Who doesn’t know the spider plant (Chlorophytum comosum) with its long arching stolons (in fact, flower stems) bearing baby plants? However, unlike the kalanchoe, the babies aren’t normally invasive unless they happen to touch a pot of moist potting soil, as they don’t break free on their own. Instead, it’s the fairly insignificant small white flowers that produce pods of small black seeds that lead to small spider plants popping up in neighboring pots. They’re helped along by the fact that most people grow spider plants in hanging baskets, so their seeds can readily drop into any pots below.

Do note that any seedlings produced are all green, never bearing the cream to white stripes typical of most spider plant cultivars.

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Orange spider plant (Chlorophytum orchidantheroides)

C. comosum is not the only spider plant that self-sows a bit too vigorously. The orange spider plant, confusingly known by several names, including C. orchidantheroides, C. amaniense and C. orchidastrum, sometimes modified by the cultivar name ‘Fire Flash’, can also be invasive. Nothing like its grasslike cousin, it forms a rosette of fairly broad leaves with an orange petiole and midrib and does not produce hanging stems. Still it blooms readily and its seeds can jump from pot to pot.

The same also goes also for the large-leaved spider plant (C. macrophyllum), another rosette type with large green leaves. It is, in fact, the most invasive of the three.

Madagascar Jewel

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Madagascar jewel (Euphorbia leuconeura)

Most of the succulent euphorbias (Euphorbia spp.) stay in the pots you planted them in, but there is one exception: Madagascar jewel (Euphorbia leuconeura), with an erect swollen stem, eventually quite treelike, and oblong leaves with white veins, at least on young plants. The flowers are insignificant, but produce a seed pod that “explodes” at maturity, launching seeds in all directions, up to 15 feet (5 m) from the mother plant.

You often find this euphorbia in plant exchanges: people who have one always have plenty of babies to give away!

Grendelion

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Grendelion (Dorstenia foetida)

This truly bizarre (and frankly, none too pretty) succulent in the fig family, Dorstenia foetida, produces one or more uptight succulent stems with a bulbous base and intriguing flat shieldlike flowers looking vaguely like a green sunflower. It too launches its seeds everywhere.

Umbrella Palm

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Umbrella palm (Cyperus alternifolia)

Also called umbrella sedge and umbrella papyrus, the umbrella palm (Cyperus alternifolius) is a popular grasslike houseplant that grows best when left constantly soaking in water. It has a characteristic whorl of narrow leaves at its stem tips. Under good conditions it produces a profusion of pale green flowers that turn brown over time and these release light-as-air seeds that germinate in nearby pots, producing little plants that look just like tiny clumps of grass at first.

Artillery Plant

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Artillery plant (Pilea microphylla)

The artillery plant or artillery fern, Pilea microphylla, is not a fern, but the arching stems bear tiny leaves and flowers so small that you can scarcely see them without a magnifying glass. That doesn’t prevent it from invading the pots of other plants through its extra-tiny seeds, though!

Creeping Woodsorrel

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Creeping Woodsorrel (Oxalis corniculata)

This trifoliate plant with yellow flowers (Oxalis corniculata) is strictly a weed: no one would ever think of growing it on purpose. Even so, this small Eurasian weed somehow made its way into commercial greenhouses at some time in the distant past and is now a common houseplant weed worldwide, especially in pots of cactus and succulents. It isn’t too strict about C&S plants though, and will move in on any of your houseplants if you don’t ruthlessly yank it out before it produces seed.

Ferns

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Holly fern (Cyrtomium falcatum)

Ferns produce lighter-than-air spores and therefore can travel through our homes on air currents. They can land anywhere, although most need moist conditions in order to sprout. They love my basement where I find them growing in many pots, especially in seed trays, where the high humidity is much to their liking. Among the species suffering from wanderlust are holly fern (Cyrtomium falcatum), ladder brake (Pteris vittata) and maidenhead ferns (Adiantum raddianum and others).

Whisk Broom

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Whisk broom (Psilotum nudum)

This bizarre plant (Psilotum nudum) has no roots or leaves, only thin green upright branches that fork repeatedly and a creeping underground rhizome. Bunched together, the branches can be used as a small broom, whence the common name. Long classified as a fern ally, the whisk broom was recently determined to be a true fern, albeit a very primitive one. Its spores are carried about by moving air. Oddly, they germinate underground (most ferns germinate on the soil’s surface) and start their life as a parasite on soil fungus, a very unfernlike habit indeed.

Mosses

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Mosses in a flower pot

Yes, mosses also settle in our houseplant pots, most probably brought in from outdoors by the wind, as their spores are so small they can easily slip through window screens. Mosses mainly tend to appear in soil that is on the moist side, such as in pots of seedlings, but you’ll even find them in cactus pots.

Personally, I just let mosses grow: they create a nice green carpet that hides the soil from view and don’t harm their host. Terrarium lovers too enjoy mosses and often install various types in their miniature gardens.

Liverworts

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Liverwort (Marchantia sp.)

Liverworts (Marchantia spp.) are closely related to mosses, but they’re much less welcome than mosses when they show up in pots. That’s because they form soil-hugging carpets so dense that the soil’s air circulation is compromised and that can lead to the pot’s main inhabitant to suffer from root rot. To get rid of liverworts, scrape off a ½ inch (1 cm) layer of potting mix and replace it with fresh soil. Be careful how you water, too, as the presence of liverworts often indicates overwatering.


If you grow houseplants, sooner or later you’re bound to find one or more of these invasive plants in your pots. It’s up to you to decide whether they are enemies to eliminate… or cute new plants that deserve their own pot!20170116a