The ZZ Plant: The Aberrant Aroid

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The ZZ plant may be a fairly new introduction, but it’s already seen as a “classic houseplant.” Source: fleurenville.com

The ZZ or zeezee plant (Zamioculcas zamiifolia), also called aroid palm, has been around long enough to have become a staple houseplant for indoor decors, but that wasn’t always the case. Although discovered back in the early 19th century (it was first described botanically in 1829) in eastern Africa, its potential as a houseplant went unknown for over 150 years. Dutch horticulturists, seeing it used as an ornamental plant outdoors in tropical Asia, tried it indoors and the rest is history. By 1996, it was being mass produced. By 2000, it was essentially available all over the world.

What Is It?

The ZZ plant is an aberrant aroid.

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Most aroids look nothing like the ZeeZee plant. Source: www.fairchildgarden.org

The aroid or philodendron family is best known to most gardeners for its climbing foliage plants, including not only the ever-popular heartleaf philodendron (Philodendron hederaceum, formerly P. scandensP. cordatum and P. oxycardium), but such other indoor climbers as the pothos or devil’s ivy (Epipremnum aureum), the Swiss cheese plant (Monstera deliciosa) and the syngonium or arrowhead vine (Syngonium podophyllum). Of course, the vast family does contain a lot of other plants, including such tuberous tropicals as caladiums (Caladium hortulanum), taro (Colocasia esculentum) and any other plant commonly called an elephant’s ear, a few classic table-top houseplants peace lily (Spathiphyllum spp.) and Chinese evergreen (Aglaonema spp.) and even a few very hardy perennials for the outdoor garden, like the Jack-in-the-pulpit (Arisaema triphyllum), native to cool to cold climates in North America.

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Zamioculcas zamiifolia on the left; Zamia furfuracea, on the right. They certainly do look a lot alike, although they are not related. Source: www.plantsrescue.com & http://www.gumtree.com

However, the ZZ plant looks like no other aroid. With its clump of pinnate leaves arching outwards, you’d be more likely to mistake it for a palm or a cycad, possibly even a fern. That’s reflected in its botanical name: Zamioculcas zamiifolia. It’s named after the genus Zamia, short palmlike cycads from the New World which it certainly does resemble.

It is so aberrant that it has no truly close relatives: it is, in fact, monotypic, the only plant in the genus Zamioculcas. It even has its own subfamily that it shares with no other aroid, the Zamioculcadoideae.

A Closer Look

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Underground and out of sight are potato-shaped tuberous rhizomes. Source: Mokkie, Wikimedia Commons

Underneath the cycad-like exterior is a tuberous plant, growing from a fat, potato-like rhizome hidden or mostly hidden under the soil. Extremely thick, succulent petioles arise from the rhizome bearing about 6 to 8 pairs of very shiny, dark green leaflets. Such pinnate leaves are typical of palms, cycads and ferns, but not other aroids.

The plant usually reaches about 2 to 3 feet (60 to 90 cm) in height and spread.

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The flower of the ZZ plant is typical for an aroid. Source:  Mokkie, Wikimedia Commons

Small, typically aroid inflorescences, with a greenish to bronze spathe (leaf-like bract) from which emerges a cream to brown colored spadix (flower spike), appear on very short stems at the base of the plant, often so well hidden you don’t even notice them. Certainly, they contribute little to the plant’s appearance.

One Tough Cookie

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You can put a ZZ plant almost anywhere indoors, even a dark corner, and it will survive for many, many months. Source: Eveline Mallmann, pinterest.ca

The ZZ plant is extremely tolerant of indoor conditions (it also makes an easy-to-grow shade plant for the tropics, but that’s another story). It will grow just about anywhere, from full sun to deep shade, and seems to thrive in neglect. Even so, you’ll get better results if you “treat it kindly,” and that would include giving it good light with some direct sun each day and avoiding spots in full sun during the hotter months of the year.

Of course, while it will “hold” for months in a dark corner that receives no sunlight at all, that will eventually kill it: it’s a living plant after all and all green plants need at least some light!

Rumor has it that the ZZ plant never needs to be watered. That’s nonsense, of course: all living plants need water!

This plant is essentially a succulent (again, aberrant in aroids), native to forests and savannahs where severe drought can occur. As a result, it prefers fairly arid conditions to the humid jungle-like environment most other aroids favor. That helps make it easy to grow, as it will tolerate considerable neglect. Even so, it does best when watered regularly, as soon as the soil is dry to the touch. And when you do water, do so thoroughly, completely humidifying the root ball.

Overwatering can lead to rot, so be sure the growing mix is almost dry before watering again. Sink your index in the substrate to the second joint: if it’s still moist, it’s not yet time to water!

It will tolerate so much neglect you can actually not water it at all for months on end. That will eventually push it into dormancy, though, a state from which it will (slowly) recover when you start watering again. I had a friend whose ZZ plant accidentally got stored in a box for over 2 years: therefore, with no light or water. It was leafless by then, of course, but when water was applied again, it started to regrow, albeit several months later.

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The ZZ plant will grow in almost any decor… but it doesn’t like cold temperatures. Source: www.bakker.com

This plant’s well-deserved “tough-as-nails” reputation only applies if you keep it fairly warm. It is perfectly happy at normal indoor temperatures, that is, between 65° and 80 °F (18 °C and 26 °C), but does not like cool temperatures and can die if exposed to temperatures below 60 °F (15 °C) for any extended period. If you put yours outside for the summer, do make sure you bring it back inside early.

The ZZ plant is certainly not a heavy feeder and will probably do fine even if you never fertilize it, but to maintain good growth, a regular fertilizer regime at ⅛ to ¼ of the recommended rate, applied during its spring through early fall growing season, is best. You can use the fertilizer of your choice.

Finally, repot after a few years or when the plant outgrows its pot.

Propagation

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A ZZ plant cut into two and ready to be planted. Source: www.jackwallington.com

Mature plants can be divided, although they may take 5 years or more to reach a size where you’d be comfortable trying. Study at your plant and if you can see it’s composed of two or three distinct clumps, you can unpot it, separate the clumps by cutting between them with a sharp knife and repot them individually.

Mostly, though, home gardeners start new plants from leaflet cuttings.

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Leaf cuttings at various stages. Source: edis.ifas.ufl.edu

The leaflets are actually quite fragile and easily knocked off: always a good excuse to try a bit of multiplication. Just insert the lower end of the leaflet into a moist growing medium and water as needed so it doesn’t become totally dry … and that means not very often. Perhaps once a month or so.

An underground tuber-like growth forms first and, then roots and finally, a first leaf. Sometimes the green leaflet has time to turn yellow, then brown before there is any visible sign of life above ground, but don’t give up: there is probably a tuber at the base of the leaf and, if so, a new plant will form, although that can take a year, sometimes even two … and no, that is not an exaggeration!

You can also use an entire leaf as a cutting, but you’ll still just get one plant at the end.

Pests and Problems

As mentioned, rot is the most likely cause of any ZZ plant death. It usually sets in when the plant is left soaking in water for long periods. Remember, with this plant, water only when the potting mix is truly dry to the touch.

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Scale insects and their sticky dejections on a ZZ plant. Source: ask.extension.org

Mealybugs and scale insects just love the ZZ plant and are hard to control. I once tried putting a scale-infested plant into complete dormancy, forcing it to lose all its leaves. Then I dug up and thoroughly cleaned the rhizomes. When it grew back many months later, the scale insects came back too!

Try removing any visible insects with a soft, soapy cloth, then spray repeatedly with isopropyl alcohol (rubbing alcohol) to, hopefully, kill any nymphs. If that doesn’t work, toss the plant and only use the pot again after a truly thorough cleaning.

Toxic or Not?

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The ZZ plant is not edible, but then, apparently not as poisonous as once thought either. Source: clipartxtras.com

The ZZ plant is an aroid, all of which are usually considered poisonous because they produce calcium oxalate, which can cause painful irritations if ingested. For years, the ZZ plant was thus deemed “guilty by association” and even listed by many sources as highly toxic.

However, recent studies suggest that the ZZ plant is considerably less toxic than most other aroids and in fact, possibly not toxic at all.

While waiting for further studies to be done, it would still be wise to keep this plant out of reach of children and pets.

Cultivars

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Variegated ZZ plant. Source: MonsteraCo.

Recently, a few cultivars have appeared, none widely available at the moment.

‘Raven’, with dark purple black foliage on a more compact plant (30 inches/75 cm).

‘Zamicro’, a dwarf version (16 inches x 12 inches/40 cm x 30 cm) for tight spots.

There is also a variegated ZZ plant out there (I saw one specimen in the Berlin Botanical Garden and it was gorgeous!), but it’s outrageously expensive.


The ZZ plant: original and easy to the point of being nearly unkillable. Give one soon as a gift to some poor brown thumber who desperately needs a bit of a confidence boost in his or her gardening abilities!

50 Houseplants That Don’t Mind Dry Air

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Most houseplants just don’t do well in desert-dry air! Source: pexels.com

Dry air is a major problem for houseplants in the winter… and indeed, any indoor plant (seedlings, cuttings, etc.). When the atmospheric humidity is less than 40%, certainly common enough in many homes, plants try hard to compensate by transpiring more heavily, that is, by releasing water to the air through their stomata (breathing pores). The drier the air, the more they transpire, and that can lead to their tissues losing water more rapidly than their roots can replace it. This can result in all sorts of symptoms of stress: wilting, flower buds turning brown, leaves curling under, brown leaf tips, even the death of the plant.

And if that weren’t enough, leaves stressed by dry air are also more subject to pest damage (red spider mites, whiteflies, thrips, etc.)

Some Plants Can Cope

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Plants with thick, waxy leaves cope better with dry air than those with thin ones. Source: davisla.wordpress.com.

That said, many plants, especially those native to arid climates or ones where they are exposed to long periods of drought, have developed ways of compensating for dry air. Cacti and succulents are usually very resistant to dry air and so are some epiphytic plants, like hoyas.

Some plants resist dry air by producing leaves with fewer stomata than normal, thus reducing water loss. Many have abandoned leaves altogether and breathe through their green stems (many cacti, for example). Others keep their stomata closed during the day, when the sun is hottest and water loss is greatest, breathing only a night. (This is called Crassulacean acid metabolism or CAM.) In other words, they essentially hold their breath 12 hours a day! Also, plants resistant to dry air often have extra-thick leaves or leaves coated with wax, powder or hair, all of which reduce evaporation.

Plants That Don’t Mind Dry Air

What follows are a few houseplants that don’t really mind it if the air in your home is on the dry side. Not that they will suffer if you increase the humidity to levels more acceptable to plants in general (most plants prefer a relative humidity of 50% or above) and that indeed is good for your health too, but if improving the atmospheric humidity something you just can’t do, at least these plants will pull through without a complaint!

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Aeonium arboreum ‘Atropurpureum’: one example of a plant that tolerates dry air. Source, Bernard Dupont, Wikimedia Commons

  1. Aeonium spp. (tree houseleek)
  2. Agave spp. (century plant)
  3. Aglaonema spp. (Chinese evergreen)
  4. Aloe spp. (aloe)
  5. Ananas comosus (pineapple plant)
  6. Aspidistra elatior (cast iron plant)
  7. Beaucarnea recurvata (ponytail palm)
  8. Cephalocereus senilis (old man cactus)
  9. Cereus peruvianus (Peruvian apple cactus)
  10. Ceropegia woodii (rosary vine)
  11. Clivia miniata (clivia)
  12. Crassula ovata (jade plant)
  13. Crassula spp. (crassula)
  14. Cryptanthus spp. (earth star)

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    The thick leaves of the dieffenbachia can generally cope quite well with drier air, but you can see just a bit of damage at the tip of this one. Source: Forest & Kim Starr, Wikimedia Commons

  15. Dieffenbachia spp. (dumbcane)
  16. Echeveria spp. (echeveria)
  17. Echinocactus grusonii (golden ball cactus)
  18. Epipremnum aureum (pothos, devil’s ivy)
  19. × Epicactus (orchid cactus)
  20. Euphorbia lactea (candelabra spurge)
  21. Euphorbia milii (crown of thorns)
  22. Euphorbia tirucalli (pencil cactus)
  23. Ficus elastica (rubber tree)
  24. Ficus lyrata (fiddle leaf fig)
  25. Gasteria spp. (ox tongue)
  26. Gymnocalycium mihanovichii friedrichii ‘Hibotan’ (red ball cactus)
  27. Haworthia spp. (zebra plant)
  28. Hippeastrum cvs (amaryllis)
  29. Hoya carnosa (wax plant)
  30. Kalanchoe (kalanchoe, panda plant)
  31. Ledebouria socialis (silver squill)

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    Few plants tolerate dry air as well as living stones (Lithops). Source: Dysmorodrepanis, Wikimedia Commons

  32. Lithops spp. (living stone)
  33. Mammillaria spp. (pincushion cactus)
  34. Opuntia spp. (bunny ears)
  35. Pachypodium lamerei (Madagascar palm)
  36. Pelargonium graveolens (rose-scented geranium)
  37. Pelargonium × hortorum (zonal pelargonium, zonal geranium)
  38. Peperomia obtusifolia, P. clusiifolia (baby rubber plant)
  39. Philodendron hederaceum oxycardium (heartleaf philodendron)
  40. Rhipsalis spp. (mistletoe cactus)
  41. Sansevieria trifasciata (snake plant)
  42. Schlumbergera (Christmas cactus)
  43. Sedum spp. (sedum, donkey’s tail)

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    The nearly round leaves of Senecio rowleyanus are designed to reduce evapotranspiration. Source: Forest & Kim Starr, flickr

  44. Senecio rowleyanus (string-of-pearls)
  45. Senecio serpens (blue chalksticks)
  46. Stapelia spp. (carrion flower)
  47. Streltizia reginae (bird of paradise)
  48. Syngonium spp. (arrowhead vine)
  49. Yucca elephantipes (spineless yucca)
  50. Zamioculcas zamiifolia (zeezee plant)20171227A pexels.com