fasciation what causes it?

[animartco]

Interesting phenomenon isn't it? Does anyone know the cause? Some plants do it lot others hardly ever, and it doesn't seem to run in families as far as I know.
Here is a picture I took this morning in the garden of a black bryony plant

[Dorts]

The cause is not known, though I believe it is most likely to be due to one of the many plant viruses messing about with the plants hormones and also particularly the cells at the growing tip.
It occurs in many flowers, trees and ferns but not often found in grasses.
Seems to be more prevalent after a wet spring.

[jaguarondi]

I once wrote an article on plant deformities for an agricultural magazine and incorporated a brief section on fasciation. I think that section took me longer to write than the rest of the article put together because I wanted to know what caused it. I got the impression that it is rather complicated. Apparently genetics can alter susceptibility to fasciation but there needs to be some sort of a trigger, like a virus as Dorts suggests, or severe weather.

[animartco]

Hi Dorts and Gaguarundi. If it is severe weather then we should expect a lot of it this year? I suppose you'd need public participation to prove a weather link, with reports of sightings from year to year. Though there is a plant which is deliberately grown with fasciation, and sold as a pot plant. Can't remember the name of it. The leaves are like a calceolaria, and it has a similar lush habit, and in the normal form a mophead of little flowers. It would be interesting to know what they do to get the fasciation.

[captivebolt]

I don't know, but it's a fasciating question . . .

CB

[Paul mabbott]

Caused by viruses which may be exacerbated by other factors.

[The Woodman]

A fasciated stem involves a flattening of the normally cylindrical stem and can result in a much heavier growth due to the formation of rows of linked meristems instead of a single one at the apex of the shoot.

In some cases the fasciated tip can split causing antler like growths. This phenomenon can be annual and the terminal buds resume their normal growth or it can be chronic.

It is thought that it could be caused by wound stimulation, possibly by aphid or weevil attack or over nutrition. Little evidence supports these hypotheses but as Paul says, a viral infection may play a big part. Fasciation of Pinus pinaster over in Madeira can be so profuse on individual trees as to cause death. I do wonder if a heavy insect (sap suckers) loading or sap bleed / bark damage caused by harsh environmental conditions contributes to this and an infection route is opened.

Roost have also been discovered with fasciation.

[animartco]

Very interesting Woodman, but why do the Meristems link?. The plant in the picture by the way has normal growth at the bottom. The fasciation only occurs as the stems reach the top of the supporting elder, which was halved in height earlier in the year. If the stems flatten and then join, could this be allied to inarching? Although I do not think they are individual stems which have joined. Isn't it rather a change of shape in section from round to an elongated corrugation? It is especially interesting in black bryony perhaps because it does not have stems that branch. Each stem comes up from the ground.

[Hedera]

I had a fasciated dandelion flower, complete double-header. That's a hollow stemmed plant. Also my neighbour's forsythia often has stems about 2" wide and flattened.

[captivebolt]

I have e-mailed this question to David Harper, Lecturer in Evolutionary Biology at the University of Sussex. It may be a while before I get a reply but I will post when I hear from him.

CB