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Succulents, Fibonacci and Spiral Phyllotaxis

Many cacti and succulents form geometric spirals similar to those of sunflowers, pine cones and nautilus shells. Spiral leaf arrangements funnel rain to roots, and keep upper leaves from shading lower ones.

The arrangement of a plant’s leaves along the stem is phyllotaxis (from ancient Greek, phýllon “leaf” and táxis “arrangement”). Mathematically, spiral phyllotaxis follows a Fibonacci sequence, such as 1, 1, 2, 3, 5, 8, 13, etc. Each subsequent number is the sum of the two preceding ones.

There’s a hypnotic beauty about spiral phyllotaxis, not to mention it’s a great word to impress friends with. As is the puzzling-to-pronounce Fibonacci (fee-bo-NACH-ee), who was a 12th-century Italian mathematician.

Perhaps the best known succulent to do this is aptly name spiral aloe (Aloe polyphylla). Unfortunately it’s devilishly tricky to grow, making it the Holy Grail of succulents. (If you can grow a spiral aloe, you can grow anything.)

Aloe polyphylla, also known as Spiral Aloe

I’m fond of spherical cacti because of how their spines spiral—in fact, I almost prefer the plants out of bloom. These are mammillarias. I show a cool way to display them in another article, Create a Cactus Curio Box. And I describe the growing popularity of these photogenic plants in Is Cactus the New Black?

mammillaria

Sempervivum arachnoideum, cactus spiral

Sempervivum arachnoideum, cactus spiral

Sempervivums (hens-and-chicks) also spiral beautifully. Squint at this photo and you’ll see how similar it is to the center of a sunflower.

Sempervivum arachnoideum, cactus spiral

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Medusa euphorbias, known for their craggy, snakelike stems, each has a spiral at its center. No two are the same, and seldom do you find one that’s perfect.

Medusa euphorbia

Have you noticed spiral phyllotaxis in your own garden? Do look for it. You may be surprised at how it jumps out at you, once you’re aware of it. For example, this common succulent (Graptopetalum paraguayense) exhibits spiraling, albeit more subtly than the examples above.

You may even see it on nonorganic items, like book bags. 

Related Info

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If you enjoy gardening,you’ve no doubt experienced how it can be a form of meditation and a treat for all the senses. But have you considered how simply looking at certain plants induces a feeling of serenity? You can discover this simply by enhancing a sitting area with succulents that incorporate geometric patterns and spirals…[Continue reading]
 
Long a pariah plant, cactus is becoming cool. The first edition of my book, Designing with Succulents (Timber Press, 2007) showed few cacti—mainly golden barrels. A decade later, the completely revised second edition devotes 15 pages to numerous varieties of spiny succulents in gardens large and small. [Continue reading]


 

Debra Lee Baldwin, Garden Photojournalist, Author and Succulent Expert

Learn more about Debra Lee Baldwin, garden photojournalist, author and succulent expert

 


 

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