The mulberry genus - Morus - comprises about 12 species of deciduous trees and shrubs native to temperate and subtropical regions of Asia, Europe, and North America (Rehder 1956). Seeds of 2 native species and 2 naturalized species are described here (table 1). White (sometimes called "Russian") mulberry was introduced to the United States by Mennonites from Russia in 1875. The United States Prairie States Forestry Project planted an average of over 1 million trees of this species annually from 1937 through 1942 for windbreaks in the Great Plains from Nebraska to northern Texas (Read and Barnes 1974). The high drought resistance of white mulberry makes it well suited for shelterbelt planting (Read and Barnes 1974).
Barbour, Jill R.; Read, Ralph A.; Barnes, Robert L. 2008. Morus L.: mulberry. In: Bonner, Franklin T.; Karrfalt, Robert P., eds. The Woody Plant Seed Manual. Agric. Handbook No. 727. Washington, DC. U.S. Department of Agriculture, Forest Service. p. 728-732.