Fasciation (or 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 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. 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 and environmental causes.
Fasciation can be caused by hormonal imbalances in the meristematic cells of plants, which are cells where growth can occur. Fasciation can also be caused by random genetic mutation. Bacterial and viral infections can also cause fasciation. The bacterial phytopathogen Rhodococcus fascians has been demonstrated as one cause of fasciation, such as in sweet peas (Lathyrus odoratus) plants, but many fasciated plants have tested negative for the bacteria in studies, hence bacterial infection is not an exclusive causation.
Additional environmental factors that can cause fasciation include fungi, mite or insect attack and exposure to chemicals. General damage to a plant's growing tip and exposure to cold and frost can also cause fasciation. Some plants, such as peas and cockscomb Celosia, may inherit the trait.
Fasciation is not contagious, but bacteria that cause fasciation can be spread from infected plants to others from contact with wounds on infected plants and from water that carries the bacteria to other plants.
Although fasciation is rare overall, it has been observed in over 100 plant species, including members of the genera Acer, Aloe, Cannabis, Celosia, Delphinium, Digitalis, Euphorbia, Forsythia, Glycine max (specifically, soybean plants), Primula, Prunus, Salix and many genera of the Cactaceae (cactus) family. Cresting results in undulating folds instead of the typical "arms" found on mature Saguaro cactus.
Some varieties of Celosia are raised especially for their dependably fasciated flower heads, for which they are called "cockscomb". The Japanese Fantail Willow (Salix sachalinensis 'Sekka') is another plant that is valued for its fasciations.
Fasciation caused by damage to genetic material and by bacteria can be controlled by not using and disposing fasciated plants. Avoiding injury to plant bases and keeping them dry can reduce the spread of bacteria. Avoidance of grafting fasciated plants and the pruning of fasciated matter can also reduce the spread of bacteria.
Fasciation on Digitalis. Note the larger thickened stem compared to the normal-sized flowering spike on the left.
Fasciation on a Flowering Cherry (Prunus) tree
Asparagus (Asparagus officinalis) fasciation. Note the flattened state of the stem. Image circa 1892-1893.
Common Dandelion displaying both regular (upper right) and fasciated (center) flowers.
Fasciation on a Lilac shrub.
Fasciation on a Phacelia campanularia or California Bluebell wildflower.
- White, Orland E. (June 1948). "Fasciation (Preview, page 319)". Volume 14, No. 6. The Botanical Review. pp. 319–358. Retrieved July 7, 2012. DOI: 10.1007/BF02861723 (subscription required)
- Albertsen, Marc E.; et al. (June 1983). "Genetics and Comparative Growth Morphology of Fasciation in Soybeans (Glycine max (L.) Merr.) (Preview, page 263)". Volume 144, No. 2. Botanical Gazette. pp. 263–275. Retrieved July 7, 2012. (subscription required)
- Morris, Scott. "Fasciation in Flowers – What You Need To Know". Gardentoolbox. Retrieved 10 January 2014.
- Lerner, B. Rosie (September 2007). "Fascinating Fasciation". Purdue University Extension. Retrieved July 3, 2012.
- Galun, Esra (2007). Plant Patterning: Structural and Molecular Genetic Aspects. World Scientific Publishing Company. p. 333. ISBN 9789812704085
- "Fasciation in Vegetables and Fruits". University of Delaware Cooperative Extension. May 27, 2011. Retrieved July 6, 2012.
- Tilford, P.E. (1936). "Fasciation of Sweet Peas caused by Phytomonas fascians n.sp.". Volume 53, No. 5. Journal of Agricultural Research. pp. 383–394. Retrieved July 7, 2012. (subscription required)
- Swift, Curtis E. (April 12, 1999). "Fasciation: Fascinating distortions of the plant world". Colorado State University Extension. Retrieved July 3, 2012.
- "Pests in Gardens and Landscapes". Statewide Integrated Pest Management Program, Agriculture and Natural Resources, University of California. October 13, 2008. Retrieved July 3, 2012.
- Yamamoto, Etsuo; et al. (April 25, 2000). "Molecular characterization of two soybean homologs of Arabidopsis thaliana CLAVATA1 from the wild type and fasciation mutant (Abstract)". Volume 1491, Issues 1-3. Gene Structure and Expression. pp. 333–340. Retrieved July 7, 2012. (subscription required)
- "Campus Arboretum". University of Arizona. 2008-08-20. Retrieved 2010-01-14.
- White, Orland E. (1945). "The Biology of Fasciation (Preview, page 11)". Volume 36, Issue 1. Journal of Heredity. pp. 11–22. Retrieved July 7, 2012. (subscription required)
- Crespi, M.; et al. (March 1992). "Fasciation induction by the phytopathogen Rhodococcus fascians depends upon a linear plasmid encoding a cytokinin synthase gene". Volume 11, No. 3. The EMBO Journal. pp. 795–804. Retrieved July 7, 2012.
- Nilsson, O.; et al. (October 1996). "Expression of the Agrobacterium rhizogenes rolC Gene in a Deciduous Forest Tree Alters Growth and Development and Leads to Stem Fasciation". Volume 112, No. 2. Plant Physiology. pp. 493–502. Retrieved July 7, 2012.
- Crespi, M.; et al. (May 1994). "The fas operon of Rhodococcus fascians encodes new genes required for efficient fasciation of host plants (Abstract)". Volume 176, No. 9. Journal of Bacteria. pp. 2492–2501. Retrieved July 7, 2012. (subscription required)
|Central Texas Gardener: Fasciated Mountain Laurel. KLRU-TV, Austin PBS.|
|Wikimedia Commons has media related to Fasciation.|
|Wikimedia Commons has media related to Crested plants.|
- Ombrello, T. (PhD). "Fascinating Fasciated Plants". Union County College, Cranford, NJ. Retrieved July 6, 2012.
- "Definition of "Fasciation"". Merriam-Webster Dictionary. Retrieved July 6, 2012.