Mulberry (Morus): how to identify it

Red mulberry vs white mulberry

Once you know it's a mulberry, the leaf surface usually tells which one. Rub the top of a leaf between your fingers.

The University of Florida's red mulberry fact sheet describes the upper surface as "dull green and rough" with a hairy, fuzzy underside, while Utah State University Extension describes white mulberry leaves as dark green, glossy and usually hairless on both sides. Fruit color is the weakest test: white mulberry fruit, despite the name, can ripen pink, red, purple or nearly black.

Hybrids. The USDA Forest Service's white mulberry review reports that white mulberry hybridizes with red mulberry in North America, that the two species are "highly variable and frequently confused", and that hybrids in Ontario resembled their white mulberry parents more closely, a concern for the native species. If a tree's leaves are rough on some branches and glossy on others, or everything sits in between, call it a mulberry and stop there.

How to identify a young mulberry tree

Mulberry seedlings and saplings are common in yards and along fences, because white mulberry seeds itself readily into disturbed ground. Four marks work on a tree only a few feet tall:

• Deeply lobed leaves. NC State Extension's red mulberry profile notes that lobed leaves are more frequent on new shoots and unlobed leaves in the crown, so a young mulberry often carries mostly lobed leaves. The toothed edge is still there.
• Milky sap from a snapped leaf stalk, the same as on a mature tree.
• Zigzag twigs, slender, green turning red-brown on red mulberry, gray to orange-brown on white mulberry.
• Orange bark. Virginia Tech describes young red mulberry bark as often orangish, especially when wet, and young white mulberry bark as orange-brown with lenticels.

The Forest Service records white mulberry as nonnative and invasive in the United States, establishing in floodplain and riparian forests and on disturbed ground such as roadsides, fencerows and old fields. A young mulberry in a fence line far from any planted tree is more likely white than red. For the general method on small trees, see how to identify trees by their leaves.

How to identify a fruitless mulberry tree

"Fruitless mulberry" is a nursery and landscaping name, not a species. Utah State University Extension says male white mulberry trees produce no fruit and are generally preferred for landscaping, and lists a cultivar sold simply as 'Fruitless'. Because the tree is male, it identifies exactly like any white mulberry:

• the same glossy, toothed, variably lobed leaves, usually hairless on both sides;
• the same milky sap and zigzag twigs;
• in spring, only male catkins, which Utah State describes as longer than the female ones and Virginia Tech gives as narrow, 1 to 2 inches long;
• no fruit in summer, ever, and no seedlings coming up under the tree.

A fruitless mulberry is not pollen-free. The University of Florida warns that male mulberry trees are "extremely allergenic" while female trees cause few or no allergies, so expect pollen, not fruit, from a fruitless mulberry. A tree planted in a front yard, a street strip or a parking lot that never fruits is usually one of these male trees. Our guide to trees in your yard covers how to track down what a builder or a previous owner planted.

Mulberry look-alikes

Sassafras is the tree most often confused with mulberry, because it also grows unlobed, mitten-shaped and three-lobed leaves, sometimes all on one branch. The Virginia Tech sassafras fact sheet gives the difference: sassafras leaves have an entire (smooth) margin, are green on both surfaces, and are fragrant when crushed, while broken twigs smell spicy-sweet. Mulberry leaves are always toothed, have no spicy smell and bleed milky sap. The heart-shaped leaves guide sets both against redbud, linden and catalpa.

Paper mulberry (Broussonetia papyrifera), once classified as a Morus, is in the same family and is the hardest look-alike. NC State Extension's paper mulberry profile describes toothed, oval to mitten-shaped to lobed leaves up to 8 inches long, rough on top and hairy below, much like red mulberry's. Check three things: new stems are hairy, some leaves sit opposite or in whorls instead of alternate, and the fruit on female trees is a round, ball-shaped purple-red cluster rather than an elongated berry. NC State reports it as invasive, spreading into thickets from root suckers.

Virginia Tech also lists Osage-orange and Texas mulberry among the look-alikes on both mulberry fact sheets. Neither is covered in detail here; if a tree passes the toothed-leaf and milky-sap tests but the fruit or leaves look wrong, photograph a twig with leaves and fruit and compare it with those two before settling on red or white mulberry.