White Mulberry

Morus alba L. – Moraceae – fig family

There are no donation records for White Mulberry. It is a common invasive tree in the eastern portion of the arboretum. One specimen was mapped for documentation. When measured on 24 May 2016, the tree had a diameter at breast height of 26.7 cm (10.5 in) and was in good condition. It is located at N42.24306°, W084.72755°.

White Mulberry trees are small to medium sized growing 6-18 m (20-60 ft) tall and with a trunk 30-75 cm (12-30 in) in diameter. The bark is relatively thick, light to dark gray, and furrowed into flat, wavy ridges. White Mulberry leaves are alternate, simple, and 5-10 cm (2-4 in) long and almost as wide. The shape of these leaves can vary from unlobed to a variety of lobbing. Lobed leaves are characteristic of younger trees. The leaf margin is coarsely serrated with large triangular teeth. In autumn the leaves turn a striking yellow color. Flowers bloom in May to June with the leaves. Trees are monoecious, containing separate “male” pollen producing and “female” seed producing flowers, but can be dioecious, with “male” or “female” flowers on separate trees. “Male” flowers are produced in dense catkins 1-3 cm long on short stalks. “Female” flowers are also in dense catkins 1-2 cm long on short, thinner stalks. The fruits are multiples of tiny drupes, which means that an entire “female” flower cluster forms the mulberry. Drupes are fleshy structures with a single seed also known as a “stone”. The fruits are about 1-2 cm long.

White Mulberry trees are not native to Michigan or the United States. They are native to China but have long been cultivated in Europe. The species was first introduced in the U.S. to establish the silkworm industry. The leaves of this species are the main food for the silkworm. However, once introduced the species was widely dispersed by birds and other animals that readily eat the fruits and subsequently disperse the seeds.

The White Mulberry has minimal value as a timber or landscaping species. This species is known to cause severe problems as a street or yard tree because the rapidly spreading roots are noted to frequently clog drains and pipes.  As a timber product the wood can be burned to heat homes, and it is sometimes carved and used decoratively since the wood has a vivid yellow color.

References:

Barnes BV, Wagner, WH Jr. 2004. Michigan trees, revised and updated: a guide to the trees of the Great Lakes region. Ann Arbor, MI: Univ. Michigan Press 447 p.

Michigan Flora Online. A.A. Reznicek, E.G. Boss, & B.S. Walters. February 2011. University of Michigan [Internet]. [cited 9 May-2016]. Available from:  http://michiganflora.net/home.aspx.

Skean JD, Nobert HA, Martin LC. Albion Trees. 2014. Information about the common street trees of Albion, Michigan [Internet]. [cited 9 May-2016]. Available from: http://campus.albion.edu/albiontrees/.