Fasciation

Sometimes plants grow in ways you might not expect.

Flattened stem of fasciation in milkweed (Kate Russell)

Instead of a nice round stem, you see a flattened ribbon shape. Rather than a regular flower, you get undulating folds. In flowers, it is called cockscomb or cresting. Wherever it happens, it is called fasciation.


Fasciation is a relatively rare physiological disorder that can create some beautiful mutations. It can occur anywhere on a plant, but stems and flowers are the most commonly seen examples.


How does fasciation occur?

In normal plant development, growing tips (apical meristems) focus all their resources on a single point, creating straight or cylindrical stems and flowers. Fasciation elongates the apical meristem, creating a ribbon-like growth. The Latin fascia means band.

Normal milkweed (left) and fasciated milkweed (right) (Kate Russell)

In some cases, these distortions can create unique bends, twists, odd angles, or unusual clusters of growth that look like a witch's broom. Flowers and leaves growing on these distorted stems may be smaller, more abundant, or have other unique characteristics.


One rare form of fasciation, ring fasciation, has a ring-shaped growing point that creates hollow tubes.


What causes fasciation?

Plant hormone imbalances, genetic mutations, environmental conditions, or disease can all result in fasciation. It can also occur for no apparent reason. Possible environmental factors include chemical overspray or exposure, mite or other insect infestation, and certain fungi. Exposure to cold and frost can also cause fasciation. Fasciation is not contagious unless caused by bacteria.


Plants affected by fasciation

Milkweed, nasturtiums, geraniums, dandelions, and ferns may all exhibit fasciation. It also occurs in fruits and vegetables, such as asparagus and broccoli.


Some plants are prized and propagated simply because of their fasciation.