Red Mulberry, Morus rubra

Many years ago, an uncle told me an interesting story. He said he saw birds in a mulberry tree falling out of the tree and acting strange after eating the tree’s berries. I was not surprised, having been taught that the berries are not safe to eat. This last spring, when I stumbled upon an Atlanta Magazine article that told how a group in Atlanta likes to forage for mulberries to eat, I wondered about my uncle’s story. I researched how mulberries affect animals and found that birds, squirrels, raccoons, and many other animals can actually get drunk eating mulberries and other fruit- that has fermented. When I tried to find the trees described in the article to get my first taste of mulberries, I was unsuccessful. However, I did find red mulberry trees near Mulberry Street in Austell, and the pictures in this article are from that area.

Though several mulberry species can be found in North America, only two are native to North America: red mulberry, Morus rubra, which can be found in 33 states across eastern and central North America, and Texas mulberry, Morus microphylla, which can be found in scattered areas of the American southwest.  White mulberry, Morus alba, was imported in the 17^th century from China and Japan as the preferred food of silk worms, in an effort to form a native silk industry. Black mulberry, Morus nigra, was imported from Persia as another possible food of the silkworm. It was primarily grown in Persia for its edible berries. The paper mulberry, Broussonetia papyrifera, was imported from Asia where it was important in the papermaking industry. (This tree is no longer classified in the Morus genus.) Because of loss of natural habitat and ease of hybridization with introduced species, red mulberry is becoming endangered in many states.

The red mulberry, Morus rubra, can grow to 60 to 70 feet tall and have a trunk 3 to 4 feet wide. The trunk is short, the branches are low, and they spread to form a broad, round-topped head. The Georgia Forestry Commission recorded a national champion specimen  in Richmond County in 1986 that is 54 feet tall, and it has a trunk diameter of over 7 feet. It can be seen on their website. Red mulberry trees prefer rich, moist and well-drained areas with shade from evening sun. Though happy in shady sites, those grown in more sunny areas produce more fruit. Trees can live as long as 125 years.

Red mulberry tree bark is smooth and gray-brown on young trees, with white spots that appear to have once been lenticels. Older bark is gray to gray-brown, with irregular thin plates and long, scaly ridges. Buds are larger and more flattened than those of the white mulberry, and they often sit slightly off center on the twig. Leaf stalks are usually ¾ to 1 inch long. These are all important identifiers, when being compared with other mulberries. Twigs are slender, they zig-zag, and fine, silky hairs can be seen on broken surfaces. When severed, both leaf stalks and leaves exude a milky sap that is an irritant to the skin. Leaf stalks, or petioles, may be pubescent.

Leaf appearance is oval, about 3 to 5 inches long and 2 ½ to 4 inches wide. Those in heavily shaded areas tend to be larger. Leaves may be highly dissected into lobes, or have no lobes at all-much like fig trees and sassafras trees. There is a shallow notch at the base, and a long tip. The margins are toothed. Leaf tops are dark green and slightly rough, or smooth but not lustrous.  Below, leaves are paler green and fuzzy. Leaves alternate on the stem. Autumn leaf color is yellow.

Usually, both male and female flowers appear on the same tree. However, sometimes they appear on separate trees. Female flowers are on 1 inch hanging catkins, and male flowers are on 1 to 2 inch long hanging catkins. Flowering occurs in late spring, and pollination is by wind. People with seasonal allergies may be bothered by this pollen, and areas like Tucson, Arizona have banned mulberries for this reason.

Red mulberry fruit are an aggregate of deep red or black drupelets, each containing a seed. They form a sweet and juicy cylinder that is 1 to 1 ¼ inches long. This fruit resembles that of the blackberry, but the flavor is not the same. Single fruits hang along the twigs. Unripe fruit not only does not have a good taste, but can be unhealthy. As fruit drops when ripe, gathering the fruit that falls onto a waiting cloth after shaking limbs is a good way to ensure ripe fruit. Berries may be eaten raw, after rinsing for bugs. They may also be used in any recipe that uses blackberries such as jellies, jams, pies, and wine. Unless netting is used, there may be few to gather after animals find them. Fruit can be kept unwashed in the refrigerator a few days, or they may be frozen or dried. They have a short shelf life and ship poorly, so they are not commonly found commercially.

Mulberries are not all this tree has to offer. The wood of this tree is soft but tough, and is very durable when in contact with the soil. People use the wood in making furniture, fence posts and tools. Native Americans used the tree’s milky sap to treat ringworms, and they made a tea from the roots to treat for parasites. Berries were used to aid circulation and treat dysentery. They also made clothing and rope from fibers in the tree’s inner bark, and yellow dye from the tree’s wood. There are many beneficial vitamins and minerals in mulberries. Medical conditions that have been treated using the berries include arthritis, diabetes, hypertension, constipation, and lightening skin. However, such use often has unwanted side effects. Skin care products using mulberry extract to lighten skin can cause skin cancer. Root bark extract used to help leukemia can interfere with chemotherapy. Mulberry extract used to lower blood sugar can lead to hypoglycemia. Potassium in mulberries can cause problems in people with gall bladder and kidney disorders. Mulberries may be beneficial for physical conditions, but should be used with appropriate caution.

While the red mulberry is an interesting and useful native tree, it is not without problems. It is usually not a good idea to grow the tree in urban areas, or near where you live. Tree pollen can trigger allergies and asthma. The berries dropped from the tree smell unpleasant as they rot, and the sticky mess that gets on shoes can be tracked into the house. They can stain pavements and cars. When grown for berries, the red mulberry does not produce as well as the white mulberry, which produces in clusters. However, most say the red mulberry is sweeter in taste, and worth it.

The red mulberry can be found across the eastern and central United States where it is native, but it is not common anywhere. Due to drawbacks like shade requirements, pollen irritation, and messiness, people generally do not encourage its growth. However, where it is found, people and animals are drawn to it. I’m pleased I noticed these red mulberry trees I pictured, and to think that I saw them near Mulberry Street!

Author: David

I grew up near Clayton, AL and have lived over 30 years near Atlanta, GA. My interests include family, church, guitar, gardening, working with kids... and math! Life can be very interesting. My websites: chasingtrees.net mathshortcutblog.wordpress.com View all posts by David