This section is from the book "Commercial Gardening Vol1", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A runner is a slender whip-like shoot sent out from the parent plant to root at some distance away, and at certain intervals to produce fresh plants. The Strawberry is the best-known example of a runner-bearing plant, and gardeners readily seize upon this character to raise thousands every year. New varieties of Strawberries, of course, are only obtained from seeds after a more or less lengthy process of cross-fertilizing and selection; but, once established, new varieties are also propagated from runners. Other plants besides the Strawberry throw out "runners" or "stolons", examples of which are met with in the Sweet Violet, the Houseleek, some Saxifrages (like 8. sarmentosa), and these may be used for propagating purposes. In the case of Couch Grass the underground stolons are produced with more than desirable frequency and pertinacity from the cultivator's point of view.