Fruit trees are the most attractive espaliers precisely because of their gnarliness—it creates structural interest that the winter garden might otherwise miss sorely:
Above: More than 50 'Conference' pear trees trained into an archway at West Dean Gardens in Sussex, UK. Pear trees take develop an aged look quickly. Photograph by Nina Pope via Flickr.
Above: Of course in summer you would never know they're gnarly. Photograph by Elizabeth Moriarty via Flickr.
Above: By August, nobody notices the gnarled branches in the Potager du Roi. Fruit gets the attention instead. Photograph by Emily via Flickr.
Above: The Cloisters' pear tree in June. Photograph by We Shall Meet on the Beautiful Shore via Flickr.
Above: An espaliered tree in a back corner of designer Neisha Crosland's London garden. Photograph by Christine Hanway.
Above: An espaliered apple tree (L) and trellised vines in antiques collector Will Fisher's London garden. Photograph by Christine Hanway.
For more, see DIY: Pruning Fruit Trees in Winter.