Fasciation

You may have come across a unusual growth on a shrub or herbaceous perennial. Several stems appearing flattened and fused together may appear on Forsythia or Salix and this could be 'fasciation'. I have photographed some fasciation on Euphorbia that I came across several years ago. 

The photograph shows both fasciated and normal non-fasciated growth. There is nothing to worry about fasciation, some people find it attractive, others find it ugly. The causes of fasciation are not clear, it has been linked to insect damage, frost or mechanical damage through cultivation and possibly virus infection. 

If you find fasciated growth ugly, cut it off. If not enjoy this curiosity. There are some varieties of plants actually cultivated for their fasciated growth! if the plant is a Euphorbia, please note that the milky white sap that oozes out of pruning cuts can irritate skin so wear gloves and avoid pruning in strong sunlight.