There doesn’t seem to be a predictable formula as to where and when fasciation will happen on a plant, but there are a few explanations about what and why. Fasciation comes from the Latin meaning ‘band’ or stripe and is sometimes referred to as cristation or ‘cresting’.
Where and when
Fasciation develops in the growing tips of plants (stem, root, fruit or flower head) when the plant is actively growing in spring and summer.
It generally appears randomly on a single stem, or just a few stems of a plant, and in an unpredictable manner; the plant affected may not produce the growth the following year. As with most rules there are always exceptions. For example, I have seen Liriope muscari AGM flowers be repeat performers here at Rosemoor, and Veronicastrum virginicum 'Fascination' plants are repeat ‘fasciators’, which suggests a genetic tendency to this growth habit.
What and why
Fasciation happens because there is a disruption in the growth of cells in the growing tips – the apical meristem. This triggers a response in the plant which produces abnormal growth – the fasciation.
When a part of a plant fasciates it produces wide and flattened, splayed or fused, vegetation or flowers. Looking like an alien species, the Euphorbia characias subsp. wulfenii pictured here has fasciation on a few of its stems, with one in particular being quite pronounced.
There are a few known causes of fasciation but although any of the following causes may trigger the abnormality, these aren’t predictable.
- Hormonal, genetic, bacterial, fungal, viral or environmental, which includes damage by frost, animals/insects, chemical or mechanical injury.
Plants with a name ending in ‘forma cristata’ or variations of this suggest that fasciation has been selectively propagated as a desirable characteristic. For example, Asplenium scolopendrium Cristatum Group. Among the plants most commonly affected are delphinums, euphorbias, forsythia, foxgloves, lilies and primulas.
Fasciation is nature’s way of affirming that it doesn’t always play by the rules, and is also a way of keeping us on our toes by producing freakish beauty. I love this unpredictability and clever ability to continually surprise, emphatically emphasising that we humans should always be in awe of Mother Nature.
More on fasciation
Proliferation – another plant mutation
Diagnose fasciation and other plant problems