This section is from the book "Commercial Gardening Vol4", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Three species - alba, nigra, and rubra - are stocked in nurseries, and are good for fruiting or ornamental purposes. The White and Black Mulberries are natives of the East, but the Red Mulberry (rubra) comes from the United States, where it attains a height of 70 ft. Increased by layers, or cuttings of the half-ripened shoots.