The mulberry tree, a member of the genus Morus within the family Moraceae, is not a single entity with one common place of origin. The genus includes a number of distinct species that evolved naturally in widely separated geographic regions. While many people associate the tree with Asia due to its historical link to the silk trade, the three most commonly recognized species trace their ancestral roots to three separate continents. The global distribution of Morus species today is a result of thousands of years of human migration, cultivation, and trade, linking the trees to some of the world’s oldest civilizations. This history of human movement means that the precise native range for some species has been obscured over time.
The Asian Origin of the White Mulberry
The white mulberry, Morus alba, is the most historically significant species, originating in the mountainous regions of northern China and possibly parts of South Asia. This species is linked to sericulture, the practice of raising silkworms for silk production.
Cultivation began over 4,700 years ago in China because its leaves are the preferred food source for the domesticated silkworm (Bombyx mori). The spread of the white mulberry tree was a direct consequence of the desire for silk. As silk production moved westward, the necessary food source traveled along ancient trade routes like the Silk Road.
This intentional human transport led to the tree’s widespread naturalization across Central Asia, the Indian subcontinent, and eventually into Europe and the Americas. European attempts to establish silk industries began with the introduction of Morus alba to the continent by the twelfth century. Colonists later brought the species to North America in the early 1600s in failed attempts to replicate the profitable silk trade.
The Western Asian Origin of the Black Mulberry
The black mulberry, Morus nigra, originated in Western Asia. Its native range is generally considered to be the area of ancient Persia, encompassing the mountainous regions of Mesopotamia, the Caucasus, and modern-day Iran. Unlike the white mulberry, this species was cultivated almost exclusively for its fruit, which is valued for its dark color and intense, sweet-tart flavor.
Cultivation began early in human history, with evidence suggesting its presence in the Near East at least since the Iron Age. Its spread into the Mediterranean basin and Europe was a slower, more localized process compared to the rapid dispersal of the white mulberry. Historical records indicate the black mulberry was well-known in Greek and Roman times and was carried throughout the region for its culinary value.
Because it lacked the economic engine of the silk-producing white mulberry, its distribution remained more contained. Today, the natural range of Morus nigra is still associated with its Western Asian and Mediterranean origins. Iran is often cited as a center of origin.
The North American Origin of the Red Mulberry
The red mulberry (Morus rubra) is the only major species indigenous to the Americas, having naturally evolved in Eastern and Central North America. Its expansive native range stretches from southern Ontario in Canada, west to areas of Texas and Nebraska, and south to the state of Florida.
Red mulberry trees thrive in moist sites, such as river valleys and floodplains, a habitat that distinguishes it from its Asian counterparts. Indigenous peoples utilized the fruit for food, medicine, and dyes long before European contact. The species remains an important component of the natural ecosystems across the eastern half of the continent.
Despite its native status, Morus rubra faces an ecological threat from the non-native white mulberry (M. alba). The introduced Asian species readily hybridizes with the native red mulberry, compromising the genetic integrity of Morus rubra populations. This hybridization is a conservation concern for the viability of the indigenous North American species.