Plants with Weird Leaves: Leaves That Move

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Some leaves really like to shake it up! http://www.oogazone.com & freedesignfile.com

From time to time, I like to write an article about the oddness of some leaves. Here’s yet another, about plants whose leaves actually move.

Leaves Move All the Time

The truth is, leaves that move are not that unusual. They notably move in the wind, or when touched by rain drops or brushed against. However, there are extraneous movements: the plant isn’t moving on its own, it is being moved. That said, many plants do have leaves that move themselves. You’ll learn more about them by reading the following text.

Movement for Protection

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Resurrection fern (Pleopeltis polypodioides) fronds curl up and look dead when dry, but will green up again when the rains come. Source: apalacheehills.com

Many plants have leaves that curl up or roll down under stressful conditions—drought or cold, for example—but recover afterward. The resurrection fern (Pleopeltis polypodioides, syn. Polypodium polypodioides) can survive without a drop of water for many months, even years, then its apparently dead fronds become completely green and functional within 24 hours after a good soaking. Two other resurrection plants are the rose of Jericho (Selaginella lepidophylla) and the alpine gesneriad ramonda (Ramonda spp.).

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These drooping winter rhododendron leaves will straighten up, uncurl and come back to life when warmer weather arrives. Source: http://www.indefenseofplants.com

As for movement to improve cold resistance, the thick leaves of many hardy rhododendrons (Rhododendron spp.) lose most of their moisture and both curl and hang limply all winter, giving their owners quite a scare, yet recover fully when spring returns. It’s thought this habit helps keep frost crystals from forming and damaging leaf cells.

Turning Towards the Sun

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Unless turned regularly, most houseplants will bend in the direction of the light source, Source: Donnie, http://www.houzz.com

On most plants, leaves will turn to face the direction of the sun, at least to some degree. If you transplant or otherwise move a plant—or even if you just cut an overhanging branch that was blocking the sun!—the leaf will adjust, changing its position, usually quite slowly, over days or weeks. This is particularly easy to observe on a forest edge where most light comes from the side or on a windowsill in your home if you don’t give your houseplants the traditional quarter turn regularly: most of the leaves will clearly orient towards the light. This habit of growing towards the source of light is called phototropism. (Remember that term from school?)

Night Moves

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Prayer plant (Maranta leuconeura) leaves move upward at night, like hands in prayer. Source: Aida F., http://www.pinterest.

Other plants have the curious habits of folding their leaves at night, either upward or downward, a phenomenon called nyctinasty. It’s actually very common in some plant families, such as the legume family (Fabaceae) and the oxalis family (Oxalidaceae). You may have noticed this in clover (Trifolium) or false shamrock (Oxalis triangularis), but the best-known nyctinastic plant is the popular houseplant known as the prayer plant (Maranta leuconeura), whose leaves fold up at night like hands in prayer.

This kind of movement is caused by a hinge-like structure at the base of the leaf or leaflet called the pulvinus (plural: pulvini) that is filled with water during the day, but drains at night, so that the resulting lack of turgor causes the leaf to fold.

Scientists still debate why plants do this.

Plants That Dance

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Carefully watch the fire fern (Oxalis hedysaroides ‘Rubra’)—not this photo but a real plant!—and you’ll discover it’s in nearly constant movement. Source: bluepumilio.com

There are plants that, under the appropriate conditions, take the concept of nyctinasty one step further. They too have pulvini and do close at night, but during the day, seem to be constantly readjusting themselves. The fire fern (Oxalis hedysaroides ‘Rubra’), not a fern at all, is a red-leaved oxalis sometimes grown as a houseplant, one of these “dancing plants.”

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The telegraph plant (Codariocalyx motorius) seen using time-lapse photography. You can actually see it move, but not quite that fast! Source: gfycat.com

The telegraph plant (formerly Desmodium gyrans, now Codariocalyx motorius), is another occasional houseplant with seemly motorized leaves.

Both plants will only perform when conditions are fairly warm and humid, but if you sit in from of one and watch patiently, you’ll see each leaf seems to be slowly moving, giving the impression the plant is lazily dancing. The fire fern will also react to touch, at least to a slight degree, but more about touch sensitive plants later.

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The carambola (Averrhoa carambola) has leaves that move all on their own. Source: biogeodb.stri.si.edu

The tropical fruit carambola or starfruit (Averrhoa carambola), in the Oxalidaceae, likewise has leaflets that both close up at night and move visibly, although slowly, during the day, all on their own … if you watch them patiently!

Response to Touch

Plants that react to touch are certainly the weirdest of all plants with leaves that move. This phenomenon, known as thigmonasty or seismonasty, occurs when something touches or shakes the leaf. And some will also react when you hold a match up to them. This can be incredibly rapid and is certainly visible. Again, all these plants close up at night and, again, it’s pulvinus at the leaf or leaflet’s base that empties rapidly, causing the leaf folding. Studies show that there is even an electrical current that runs between the pulvini on many of these plants, almost like nerves in animals, plus there is also a chemical reaction involved.

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Sensitive plant (Mimosa pudica). Source: worldoffloweringplants.com

The best known thigmonastic plant is the sensitive plant (Mimosa pudica), a legume also known as sleepy plant, dormilona, touch-me-not or shy plant, a decent if usually short-lived houseplant easy to grow from seed … and also a pernicious and quite prickly weed in tropical countries. A light touch will cause a single leaflet of the bipinnately compound leaf to fold inward, a firmer touch will lead to the whole leaf drooping and shaking the plant will cause all its leaves to collapse. If you run a finger down the leaf, the leaflets will close like dominoes, as in the photo below. Yet if you leave the leaf alone, it will recover in just 15 to 30 minutes.

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Mimosa pudica leaf closing. Source: Mimosa_Pudica Hrushikesh, Wikimedia Commons

It’s thought this quick reaction to touch helps prevent foraging by grazing animals. I mean, wouldn’t you stop eating if you thought you were biting into a luscious plant, then the leaves all collapsed after your tongue touched the first one, leaving the plant looking barren, unappetizing and full of (previously hidden) thorns?

M. pudica is the most commonly grown sensitive plant, but there are some 400 other species in the genus Mimosa, both herbs and shrubs, all sensitive to touch to at least some degree. There is even a hardy sensitive plant (zone 5) that can be grown as a perennial, M. nuttallii.

Note that these are true mimosas, not the trees and shrubs often called mimosas and which are actually very different, non-sensitive plants with similar pinnate leaves such as Albizia julibrissin (silk tree) and several acacias, including Acacia dealbata (blue wattle or mimosa).

There are also several species of “aquatic sensitive” (Neptunia spp.) with leaves much like those of the sensitive plant that react to touch in a similar fashion. As the common name suggests, they grow in water or at least under very boggy conditions.

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Little tree plant ((Biophytum sensitivum) has leaves that move. Kenraiz, Wikimedia Commons

Less well known is the little tree plant (Biophytum sensitivum), a small herbaceous houseplant in the Oxalidaceae that looks like a tiny palm tree and is sometimes used as a tree substitute in terrariums and fairy gardens. It is modestly touch sensitive … but its leaves move all on their own much of the time, albeit quite slowly.

Finally, the partridge or sensitive pea (Chamaecrista fasciculata), a fairly common annual species of legume native to the eastern United States, also has pinnate leaves that close at night … and are slightly sensitive to the touch during the day.

Touchy Feely Carnivores

The other group that includes plants sensitive to touch are carnivorous plants or, more correctly, insectivorous plants.

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Venus flytrap (Dionaea muscipula) with its leaf traps. To learn how to grow this capricious plant, read No Hamburger for the Venus Flytrap. Source: Citron / CC-BY-SA-3.0, Wikimedia Commons

The best known of these is the Venus flytrap (Dionaea muscipula), often offered as a houseplant, although rarely very long-lived in the average home environment. I already wrote a bit about this plant in 5 Plants with Weird Foliage. It’s bear trap-shaped leaves are dotted with tiny hairs. If an insect touches one hair, nothing will happen. This is believed to be a protection to keep leaves from closing for inopportune reasons, such as when a raindrop or a fallen leaf touches it. However, if the hair is touched a second time within 20 seconds, or if a second hair is touched within the same time limit, the cause is probably a wandering arthropod and the trap closes rapidly, in one tenth of a second. After that, the insect is slowly digested, then the trap opens again. It takes 5 to 14 hours for the trap to reopen after a false alert, while actually digesting an insect can take 10 days or more.

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The trap leaves of bladderworts (Utricularia spp.) do their job underwater, so it’s not easy to see them catch their prey. Source: wetland-plants.co.uk

Less well-known than the Venus flytrap, bladderworts (Utricularia spp.) are even faster. Their bladder-shaped trap is small modified leaf, so designed that when it is “set,” a vacuum forms inside the bladder. If a water flea or other small invertebrate touches the sensitive hair on the outside, the trap opens, instantly sucks in the creature, then closes. The whole process only takes ten to fifteen thousandths of a second.

Gardeners won’t likely find this trap as fascinating as that of the Venus flytrap, as all of this action takes place more or less out of sight underwater or even underground in soggy soil, as bladderworts are bog or aquatic plants.

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Some sundews (here, Drosera capensis) have leaves that will (slowly) wrap around the insects they have caught. Source: Noah Elhardt, Wikimedia Commons

Other insectivorous plants show some leaf movement. Some sundews (Drosera spp.) have leaves that will slowly wrap around their prey once it is glued to the sticky glands that cover them, but this happens so slowly you’d need a time-lapse camera to notice. Butterworts (Pinguicula spp.) leaves also roll up slightly when they trap a prey item, but their movement is even less impressive than that of sundews.


Leaves that move: one of Mother Nature’s little surprises!20180211A www.oogazone.com & freedesignfile.com.jpg

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5 Plants With Weird Foliage

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There is fascinating foliage all around if you just make the effort to look! Source: Clipart Library

The whole point of a leaf is to collect sunlight and convert it via photosynthesis into sugars for the plant’s growth. Thus, a leaf simply has to be green to be functional. You’d think a simple flat shape would be enough, but no. There are as many leaf shapes as there are plants and they come in far more colors than they legitimately should. Here are some of the more interesting and memorable ones.

Swiss Cheese Plant (Monstera deliciosa)

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The Swiss Cheese plant has slits and holes much like Swiss cheese. Source: Forest & Kim Starr, Wikimedia Commons

This is a very common houseplant whose leaves just keep getting bigger and bigger … and weirder and weirder. If you’ve ever grown one from a young plant, you know the first leaves are entire and heart-shaped (the Swiss cheese plant is often mistaken for a philodendron at this point). Then, as it grows, the leaves get larger and splits start to appear. As the leaf increases in size, the number of splits increases and then holes (leaf perforations) start to show up. The leaf keeps increasing in size and, as it does so, more and more perforations appear. If you have the space for this huge plant (they don’t call it Monstera for nothing!), the leaves can reach nearly 1 meter (3 feet across) and will be strikingly beautiful … and weird.

As for why the leaves become so “tattered” (and I use that word in the nicest possible way), that’s a matter of conjecture, but I like the theory that it’s because large leaves are like a banner strung across a street: if you don’t punch a few holes in them, the wind will tear them. I’ll write more about this phenomenon in a future blog.

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The inflorescence of the Swiss cheese plant is spectacular, but rarely seen except on very mature specimens. Source: Karl Wimmi, Wikimedia Commons

The Swiss cheese plant is normally a climber and will grow best when offered a (sturdy) moss stake to cling to. It tolerates low light, but for big leaves, give it as much light as you can. This will also keep it more compact. You are allowed to cut off the numerous aerial roots it produces (I like to keep a few for show). It may even bloom for you one day, with sail-like white blooms (think of a Spathiphyllum). The fruit that follows is edible when it fully ripens and its scales start to drop off and, as the name Monstera deliciosa suggests, is sugary sweet. Other than the ripe fruit, though, the plant is poisonous.

The Swiss cheese plant is easy to grow indoors, but does appreciate good atmospheric humidity (to prevent leaf browning). Otherwise, just give it regular houseplant care … and be patient!

Cooper’s Haworthia (Haworthia cooperi)

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Haworthia cooperi’s window leaves can appear completely otherworldly. This is H. cooperi truncata, with rounded leaf tips. Other varieties have pointed tips. Source: 9gag.com

I’m using this plant as an example of a window plant. There are many others in such genera as Haworthia, Lithops, Peperomia, Senecio, Fenestraria and Frithia, but all have the same fascinating characteristic: they have a translucent area at the leaf tip where sunlight can reach down through the gelatinous transparent leaf interior and reach the photosynthetic cells along the outside edges lower down. This is exactly the opposite to how other plants function. Their photosynthetic cells are located near the outside of the leaf, not buried deep inside.

Most of these window plants come from very arid climates and essentially live underground, with only their leaf tips exposed, each acting like a skylight, allowing even the buried leaf parts to photosynthesis. When we grow window plants in pots, however, sometimes we grow the plant with the entire leaf exposed, partly to show off the leaf … and partly to prevent rot.

Window plants are yet another subject I’ll cover in more detail in a future blog, but for the moment, here’s what you need to know about Cooper’s haworthia.

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Haworthia cooperi cooperi has pointed leaf tips… but the same windows as other varieties. Source: Abu Shawka, Wikimedia Commons

It’s a small, easy-to-grow succulent that will do well on almost any fairly sunny windowsill. It produces offsets and slowly the original rosette fills in the surface of the pot with the new growths. Just grow it like any other succulent, watering only when the soil is quite dry, and you’ll have success. It will even bloom quite readily, although the flowers aren’t very showy.

To best appreciate the transparent beauty of the leaves, you do need to place this plant carefully: at about eye level, with the sun in the background. When looked down on from above, the windows are not as noticeable.

You’ll find it, or other window haworthias, in most garden centers.

Venus Flytrap (Dionaea muscipula)

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The traps of Venus flytrap lie on their moss bed, awaiting the visit of a spider or insects. Source: Mokkie, Wikimedia Commons

There is no denying the plant has weird leaves. Weird in appearance and weird in how they’re used. A broad, winged, often heart-shaped petiole rises from a small rosette and it carries on normal photosynthesis, while the leaf blade itself forms two lobes, each with a ring of teeth around the outside. When an insect or other arthropod triggers the mechanism by touching the small hairs in the center of the leaf, the leaves close quickly, trapping the creature, then the leaves produce gastric juices to digest it. Yes, this plant is carnivorous, or, to be more precise, insectivorous.

Like most insectivorous plants, the Venus flytrap developed its feeding habits because it normally grows in a very sterile environment, in this case, nitrogen- and phosphorous-poor bogs in North and South Carolina. It needs insect “meat” to supplement its meager diet.

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Remove the plastic container the plant is sold in and grow it in a sunny window sitting in a saucer of rainwater. Source: www.carnivorousplants.org

Although widely sold as a houseplant, the Venus flytrap is more of a curiosity than a good indoor plant, nor will it thrive outdoors under garden conditions unless you can recreate the environment of a cold, but nearly frost-free bog (zoned 7 to 9).

In most cases, it’s best to think of this plant as a temporary one, something to be tossed when you’re finished with it.

You can keep a Venus flytrap growing for years, though, if you know what to do and are willing to bow to its whims. Read more about it in No Hamburger for the Venus Flytrap.

Mother and Daughter Croton (Codiaeum variegatum forma appendiculatum)

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Actually, with their amazing colours and strange shapes, all croton leaves are quite weird. Source: www.pahls.com

I suppose all crotons have weird leaves. Almost always variegated, they come in a wide range of colors (red, orange, yellow, purple, green and white), plus they change colors as they mature, so leaves from different parts of the plant may be very different colors. The leaf shape too is extremely variable, from ovate to linear and entire to deeply lobed, and often twisted or spiraled.

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Certainly the oddest of all crotons thanks to its leaf extensions is the mother and daughter croton. Here, the cultivar ‘Appendiculatum’. Source: www.thepaddocks.de

But the weirdest of all the crotons are those so-called called mother and daughter crotons: C. variegatum forma appendiculatum. In these, the leaf, often fairly linear, produces a narrow stalk from its tip, then a smaller leaflet, often curiously funnel-shaped, appears at the extremity. It looks like a kite on the end of a string!

I sometimes get letters from readers who think a baby plant is growing from the tip of a mother leaf. Sorry, but no dice: the croton is just not one of the plants you can grow from a leaf cutting, even less from a leaf section. You’ll need to take stem cuttings (or air layer the plant) to multiply it.

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Croton ‘Interruptum’. Source: piergrossi.squarespace.com

There are only a few cultivars with the appendiculatum habit, one being called just that: ‘Appendiculatum’. It has green leaves, although there is also a red form bearing the same cultivar name. The other often seen is ‘Interruptum’, with green leaves mottled yellow turning into red leaves mottled orange. Never is a very common plant. Unless you have a croton nursery in your neighborhood or can order one by mail, you’ll just have to wait until one of these curious mother and daughter crotons shows up in a garden center near you.

The croton has the reputation of being a persnickety houseplant, but I have specimens over 20 years old and they do just fine. Of course, I lost more than a few until I figured out that what they really need is high humidity until they settle in. Ideally, buy them in late spring or summer, when the air is naturally humid, and put them in their permanent spot, which needs to be a brightly lit one. By the time the dry air of fall arrives, they’ll have had time to adapt to your conditions and should do fine. Other than that, basic houseplant care is all they need … but do keep them out of cold air (less than 60˚ F/15˚ C).

Crotons also make great outdoor shrubs and even hedges, but only in truly tropical climates (zones 10 to 12).

Ginkgo (Ginkgo biloba)

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Ginkgo leaves are totally original: you can never mistake them from anything else! Source: www.edenproject.com

Most really weird leaves are found on tropical plants, which is normal considering the vast majority of plants on this planet are of tropical origin, but there are still many leaf oddities among hardy plants and I think the ginkgo clearly merits a spot in the list of weird leaves.

Maybe you’ve seen ginkgoes around you so often they’ve come to seem quite ordinary to you, but their leaf shape is in fact unique among seed plants. Only maidenhair ferns (Adiantum spp.) have leaflets anything like them.

Each leaf has a very special fan-shaped form, caused by veins that split in two, then split in two again and again. It’s as if the needle of a pine started out narrow, then became increasingly crested from the mid-point on. And ginkgoes are indeed gymnosperms, closer relatives to conifers than to flowering plants, in spite of their broad leaves and deciduous habit.

250 million years ago, ginkgoes were the dominant trees on our planet and were apparently a major food source for dinosaurs. There is only one species left, G. biloba, rarely found in the wild and even then only in isolated areas of Southwestern China. However, it is now grown as a cultivated plant the world over in hardiness zones 4 to 9.

The ginkgo is a very slow-growing but forgiving tree, adapting to just about every condition as long as drainage is good.

More Weird Leaves to Come

20171130A Clipart Library.jpgI’ve only scratched the surface of plants with weird leaves. I have many others I want to present to you and hope to do so over the coming months. Also, I’m looking for suggestions. Maybe I’ll be able to include your choice in one of the future blogs! If you allow me to use one of your photos, I’ll add that too! Just write me at horticom@horticom.ca.

Do note I’m looking for plants that repeatedly produce odd leaves, nor for a single mutant leaf on an otherwise normal plant, nor do leaf oddities provoked by insects or diseases count (although I have to admit some leaf galls are pretty amazing!). Also, for the moment, I’m sticking to leaves, not weird growth habits or weird flowers.

Thanks for any help you can offer!