I found a thicket of mulberries in the corner of a lot in Lithia Springs last week. This interesting find was finally determined to be paper mulberry, Broussonetia papyrifera. The tree’s name comes from the fact that paper was first made from this tree’s fiber, and an important paper industry was formed around it in China and Japan. When the paper mulberry was introduced into North America around 1785, it became widely planted as an ornamental novelty that grew quickly, provided shade, and had leaves that could be fed to silkworms. The tree is not now often encountered, due to caution over its invasive nature and its production of irritating pollen, so this tree was a surprising find.
The paper mulberry has had great economic importance in several countries. Paper was first made from this tree’s soft and fibrous inner bark in China by 100 AD, and this use spread to Korea by 130 AD and Japan by 600 AD. In the paper making process, the inner bark was pounded and mixed with water, and the paste produced was spread over a mesh and dried. The leaves were often fed to silkworms. Pacific islanders used the tree’s inner bark to produce important textiles such as tapa cloth, and they used bark and roots to make rope and cord. From the wood was made furniture, cups and bowls. The fruit of the tree was eaten, and young leaves were also eaten, steamed. Larger leaves were often used to wrap food for steaming. Leaves, fruit and bark were used medicinally. This tree has had many uses, affecting the lives of countless people.
The paper mulberry is in the family Moraceae, which includes mulberries, figs (including the rubber tree), and tropical fruits such as osage orange, jackfruit (which bears the world’s largest tree-borne fruits), breadfruit, and che. It was once classified in the genus Morus with mulberry, and it retains the mulberry common name. Now it is in the genus Broussonetia, which is to honor the French naturalist Pierre Broussonet. The main identifying features of the paper mulberry that separate it from other mulberries are its long and hairy petioles, its very hairy twigs, and its pattern of orange lenticels on the bark.
The paper mulberry tree is fast-growing, reaching 50 or more feet in height. The tree has wide-spreading branches, and the crown is broad and rounded. The tree has a shallow root system making it susceptible to wind throw. Roots spread vigorously, and can damage pipes and structures far from the tree. Root suckers come up around the tree and can emerge 75 feet from the main trunk. Trees can grow in soil of any type, but prefer soils that are moist most of the year. They like open areas that are disturbed like fields, roadsides, abandoned sites, and forest clearings and edges, but floodplain forests and river terraces are especially prone to invasion. The tree casts shade that inhibits competition. Even 
when only male trees are planted to prevent seeding, the paper mulberry is very invasive, displacing native species. Trees can be controlled through cutting and herbicide applications. The tree can tolerate temperatures below -5° C, and has been naturalized in areas from New York to Missouri, and south to Florida and Texas.
Bark on paper mulberry trees is pale brown and smooth, becoming slightly grooved on older trees. Young bark often has a striking pattern of orange lenticels. Twigs on the paper mulberry are fuzzy and reddish-brown, with leaves usually alternating but also opposite. Petioles are very long, and hairy.
Leaves have much variation in shape. Smaller leaves tend to be ovate with pointed tips and serrated margins, while larger leaves tend to be heart or mitten-shaped, and often multi-lobed with deep, irregular lobes. Leaf margins are coarsely serrated and vary greatly in size, from 3 to 10 inches. They are light green and rough above, and grayish and densely pubescent below. Leaves and petiole exude a milky white sap when cut, that is irritating to the skin. Autumn leaf color is yellow.
Male and female flowers are borne in April to May, on separate plants. Male trees bear long clusters of fuzzy flowers called catkins, which may be up to 3 
inches long. Anthers in the flowers forcibly eject pollen into the air in response to light, and trees are said to appear to be “smoking” when releasing pollen. The pollen produced is very light and does not settle like most pollen. This greatly increases the amount of pollen in the air, compounding its effects on people sensitive to it. Female trees bear greenish flowers held in spherical clusters nearly an inch wide. When pollinated, these flowers produce orange-red to reddish purple aggregate fruit balls that are round or pear-shaped, and edible. Seeds are spread by dropping fruit and animals eating it.
I asked the owner of the paper mulberry trees I found 
if she had tried eating the fruit that must have been produced on the trees. She said she had never noticed any. Only male trees were planted in her yard, in an attempt to control the invasive nature of the tree. This practice is common, preventing seeding, but it does not stop the spread of root suckers and it increases the irritation for allergy sufferers. Many areas are struggling to eliminate the tree, or have already done so. This historically important tree has served valuable purposes, but keeping it as an ornamental novelty is proving to be a struggle.
