Pleaching or plashing was common in gardens from the late Middle Ages until the 18th century. This technique is a kind of weaving of the branches of deciduous trees or shrubs to form a living fence. Sometimes branches woven together grow together, a natural grafting known as inosculation. Sir Walter Scott brought the technique back to popularity in England when he described such a fence in The Fortunes of Nigel.
Companion plants for fruit trees, including apples, pears, peaches, cherries, and plums. Great article with lots of good information. http://statebystategardening.com/state.php/il/newsletter-stories/fruittree_friends/