Fasciation

Fasciation (pronounced , from the Latin root meaning "band" or "stripe"), also known as cresting, is a relatively rare condition of abnormal growth in vascular plants in which the apical meristem (growing tip), which normally is concentrated around a single point and produces approximately cylindrical tissue, instead becomes elongated perpendicularly to the direction of growth, thus producing flattened, ribbon-like, crested (or "cristate"), or elaborately contorted tissue. Fasciation may also cause plant parts to increase in weight and volume in some instances. The phenomenon may occur in the stem, root, fruit, or flower head. Affected flowers may be referred to as "double-headed" or "two-headed", not to be confused with double-flowered flowers. Some plants are grown and prized aesthetically for their development of fasciation. Any occurrence of fasciation has several possible causes, including hormonal, genetic, bacterial, fungal, viral or environmental causes.