Garden of Eatin' / Vegetables

Romanesco Broccoli: A Fibonacci Fractal

Romanesco broccoli florets

Few things in the garden are more mesmerizing than the Italian heirloom brassica of Romanesco broccoli.

This chartreuse bud is an edible flower that is also known as a Romanesco cauliflower, but it’s technically neither — truly in a class of its own. It’s a fine work of art and a mathematical marvel. Did you know that a Romanesco is a beautiful example of a Fibonacci fractal in the natural world?

Last year I picked my Romanesco a few days too late, and its famous spiral had already started to unravel, resembling an average cauliflower. But this year, I remembered to harvest it earlier (and thankfully, it weighed much less than the 25-pound Broczilla from last year’s crop!).

The part of the broccoli that we typically eat — what we call the head — is actually the flower bud of the plant (although broccoli leaves are just as edible and delicious, and can be cooked like any other green). The tight clusters that form the head are called florets (or small flowers).

Romanesco broccoli fractals

On a Romanesco, the whole head is made up of smaller heads that mimic the shape of the larger head, and each of those smaller heads is made up of even smaller, similar heads. It keeps going, and going, and…

You’re looking at a natural fractal — quite simply, a detailed pattern that repeats itself ad infinitum. (But since a head of broccoli can’t go on forever, math purists would call this an approximate fractal, since it has a termination point.) If you break off a floret, it looks like a mini broccoli with its own mini florets. Fractals are fascinating in that way; no matter which part of the fractal you zoom in on, it will be an identical version of the bigger picture.

Romanesco cauliflower florets

A head of Romanesco broccoli

If you ever have the chance to study a tight head of Romanesco up close, you’ll see a spiral emanating from the center point, along which all the smaller florets are arranged. This is the Fibonacci spiral, a series of arcs whose radii follow the Fibonacci sequence. You remember the Fibonacci sequence from school? Where each number equals the sum of the previous two numbers? 0, 1, 1, 2, 3, 5, 8, 13, 21, and so on.

If you count the number of spirals in one direction, and then count the number of spirals in the other direction, they will be — without fail — consecutive Fibonacci numbers. Every time. Intrigued? Confused yet? I know I was. I’ll let this math geek explain it better with a visual.

If you don’t have a head of Romanesco to test out this mathematical wonder, try it with other self-similar forms; cauliflower, sunflowers, pinecones, and pineapples are all examples of Fibonacci spirals.

Isn’t it amazing how something so precise as a math formula can occur in something so organic as a head of broccoli?

Linda Ly About Author

I'm a plant lover, passionate road-tripper, and cookbook author whose expert advice and bestselling books have been featured in TIME, Outside, HGTV, and Food & Wine. The No-Waste Vegetable Cookbook is my latest book. Garden Betty is where I write about modern homesteading, farm-to-table cooking, and outdoor adventuring — all that encompass a life well-lived outdoors. After all, the secret to a good life is... Read more »