White mulberry is a medium-sized tree with a short trunk, broad, round crown, and many fine twigs.
Leaves are alternate, simple, 2–6 inches long, with 0–5 lobes, coarse teeth, pointed tip. Three main veins arise from the base. Undersurface smooth, paler than above. Bleeds milky sap. Leaf stalk smooth.
Bark is thin, brown, sometimes tinged with red or yellow, with shallow grooves and long, narrow ridges; it ages to resemble elm bark.
Twigs are reddish-brown, smooth to slightly hairy, turning gray and smooth with age. Bleed milky sap.
Flowers April–May, with male and female flowers on the same tree or on different trees. Male catkins ½–1½ inches long; female catkins ½–¾ inch long.
Fruits June–August, blackberry-like; white to pink to purple; globe-shaped to oval; ½–¾ inch long.
Similar species: Our native red mulberry (M. rubra) has leaves hairy underneath, more often lobeless, with hairy leaf stalk; its fruits are cylindrical and start out red (not white or pink); its catkins and leaves are larger. Another species, the black mulberry (M. nigra) grows in the Old World; most people think it has the best-tasting berries, which you might find in preserves or dried at international groceries.
The following leaf characters separate white mulberry from our native red mulberry:
Height: to 40 feet.
Escaped from cultivation and found in old fields, pastures, fence rows, and low, wet ground along streams. An Asian species, white mulberry was introduced by early settlers, who cultivated it for its berries and as fodder for an attempted silkworm industry. Birds have helped spread the white mulberry so much that in many places it is more common than our native red mulberry. Considered a noxious weed, white mulberry should not be planted.
A noxious weed, it was introduced to North America so early that anthropologists recorded use of the tree for medicine and food by Cherokees. White mulberry has few ornamental assets and its fruit is messy, staining sidewalks and cars. If you are wanting to plant a mulberry tree, plant the native red mulberry instead — but keep in mind that its berries are quite messy, too.
White mulberry is the favorite food of the silkworm caterpillar and in Asia is an important part of the silk-making industry. The fruit can be eaten fresh or made into jams, wine, and even ink. The wood has had various uses. In China, the leaves and bark are used for medicinal teas.
Birds flock to mulberry trees when the fruit is ripe. Biologists understand that plants produce sweet fruits as a way to disperse seeds: The fruit costs the tree energy to produce, but it rewards birds and other animals for dispersing the indigestible seeds after they eat the fruit.
There are no sharp dividing lines between trees, shrubs, and woody vines, or even between woody and nonwoody plants. “Wood” is a type of tissue made of cellulose and lignin that many plants develop as they mature — whether they are “woody” or not. Trees are woody plants over 13 feet tall with a single trunk. Shrubs are less than 13 feet tall, with multiple stems. Vines require support or else sprawl over the ground.