Did you know there was an effort to establish a silkworm industry in colonial United States? Silkworms, or the caterpillars of the domesticated silk moth, were an important economic commodity in eastern Asian countries, particularly in China, as a producer of raw silk. Along with importing the silkworms, colonists also brought over white mulberry trees whose leaves were the silkworm’s food of choice.
Unfortunately for our early settlers, the climate was not compatible for cultivation and the silkworm industry failed. The white mulberry tree, however, thrived and has spread throughout the States with the lone exception of Nevada. Due to its origins and fast-growing nature, it is considered an invasive species in many states including Indiana.
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White mulberry trees are small with light, brownish-grey bark and spread-out branches. Flowers beget a prolific number of fruits that are widely distributed by birds and other wildlife. Once established, the mulberry will aggressively colonize open, sunny areas such as fields, forest edges and roadsides ultimately resulting in the loss of native species.
The biggest ecological threat posed by white mulberry is the hybridization and possible replacement of Indiana’s native red mulberry. Unlike the invasive mulberry, which is found in every county, the red mulberry is less common. Found only in Southern Indiana’s shady, moist woods this larger, red-fruit bearing tree can easily be displaced by its exotic cousin.
The Difference between Red and White
The red mulberry is native to the state and is found in the woods of Southern Indiana. While many easily assume that the main difference between the invasive white and native red mulberry is the color of their fruit, it isn't. There are several difference between them besides and sometimes it has nothing to do with color.
Mature fruits of the red mulberry has a dark red to almost black color. The white mulberry is indeed white, but not all the time. Sometimes the fruit is a dark purple, but it can also be a pink or white. Both are consumed by birds, but only red mulberry are edible to humans. As a rare plant, those who can find the larger and deliciously sweet berries of the red species are considered quite lucky.
These best way to tell the difference between the species is to look at the foliage. The leaves of the red mulberry are dark green with finely serrated margins. The underside of the leaf is also rough and hairy. White mulberry leaves are a brighter green, and compared to the red species, have more prominent veins underneath. Bark is also a big tell; the red mulberry's bark is grayish with scaly, but flattened, ridges. The white mulbeey is a more tannish brown with thick, braiding ridges. If compared side by side, the red specie is taller than the white and has a more dense branching.
For More Information
Indiana Cooperative Agricultural Pest Survey (CAPS) profile on White Mulberry
Purdue University's Forest and Natural Resources & the Cooperative Extension Services brochure on Red and White Mulberry in Indiana
Management considerations for the invasive White Mulberry from the US Forest Service