Red Mulberry (Morus rubra) and White Mulberry (Morus alba) are treated here together, since their features are so similar, except for their differences in ripe fruit color in early summer. Red Mulberry, a species native to the entire Eastern United States, is taller and more open and gangly than its counterpart, achieving a height of 60 feet and a spread of 50 feet when found in the open.
White Mulberry, a species native to China, has been planted (and escaped) in both Europe and North America, and is more refined and dense in its branching, becoming 40 feet tall and 40 feet wide under optimum conditions. Both produce abundant amounts of fruits on their female trees, which serve as a source of food for wildlife in early summer, and which serve as the mechanism for their wide dispersal into neglected areas as a "woody weed."
As members of the Mulberry Family (Morus species), they are also related to other species of Mulberry and to Osage Orange (which, like the Mulberries, also has heavy wood with white sticky sap, a thin layer of sapwood, and heartwood that is bright yellow).
Planting Requirements - The mulberries are quite adaptable to many different types of soils (rich, poor, deep, thin, rocky, clay, or sandy) and soil pHs (acidic, neutral, or alkaline), preferring moist or dry conditions (but tolerating wet soils for short periods of time) in full sun, partial sun, or partial shade. They are also pollution tolerant, including salt deposition and salt spray. Red Mulberry is hardy from zones 5 to 9, and White Mulberry from zones 5 to 8.
Potential Problems - A host of diseases and pests can affect the leaves, twigs, and bark of the Mulberries, but none seem to slow them down, as these trees have a rapid growth rate with vigor. Witches' broom afflicts Mulberry (without harm) but is not as commonly seen as in Hackberry.
Identifying Features - Mulberry
Mulberry has a polymorphic type of leaf - that is, on the same branch, there are often multiple shapes to be seen (like the leaves of Sassafras). Some are entire (left), others are two-lobed like a mitten, and many are multi-lobed. All are shiny, dark green, and serrated or toothed, arranged in alternate fashion along the stems.
There are several subtle differences in foliage between Red and White Mulberry. Red Mulberry has leaf uppersides that are sandpapery rough and pubescent or hairy below, while those of White Mulberry are usually smooth. Leaf lobes of Red Mulberry are pointed and their leaf bases even, while lobes of White Mulberry are rounded (the leaf terminus may be pointed) and their bases are usually uneven.
Mulberry is a dioecious species, composed of male (creamy) and female (green) flowers borne on separate trees in mid-spring. Fruits mature quickly on female trees, maturing in early to mid-summer and are relished by birds, squirrels, and other mammals.
Red Mulberry matures as red-black fruits slightly before White Mulberry matures as creamy-white fruits. However, immature fruits of White Mulberry may be purple or black.
The tan twigs of Mulberry are rapidly growing and have prominent winter buds.
The golden-brown bark becomes lightly fissured, eventually forming long flat ridges and narrow fissures on mature bark.