Ash Wood Xylem (SEM)

Ash wood xylem. Scanning electron micrograph (SEM) of the wood of an ash tree (Fraxinus excelsior) in cross section (ts) and tangential longitudinal section (tls) showing xylem tracheids. The ash tree has been in the news because of Chalara fraxinea fungus, commonly known as Ash dieback which was discovered for the first time in the UK in a Buckinghamshire nursery in February 2012. It appears to be rapidly spreading with reports of the disease now coming in from many counties. Thousands of ash trees have been destroyed to try and stem the spread of the disease and the government has announced a ban on imports of ash trees as well as movement restrictions within the UK. Ash dieback causes crown dieback and leaf loss and usually leads to tree death, although some trees do survive, probably because of genetic resistance. Magnification x1180 (x300 at 10cm wide). .