White Mulberry: Tree of the Week

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The white mulberry -- Morus alba

Mulberries come in white, red and black, and are loosely named after the color of their buds and blackberry-like fruit. The red one (M. rubra) is an eastern U.S. native, the black (M. nigra) comes from Western Asia, and the white one or silkworm mulberry is native to eastern and central China. Gen. James Edward Oglethorpe in 1733 imported the tree to Fort Federica in Georgia to start a silk production industry in this country, but that proved too labor intensive.

The deciduous white mulberry tree grows fast when young to an ultimately 30-foot to 50-foot dense, irregular roundhead. Bark is rough, light gray, with distinctive vertical furrows. Branches grow so fast on young trees that they need to be cut back to create a good tree shape. Branch wood is weak. Leaves are up to 6 inches long, toothed, rough above and smooth underneath; they frequently vary in shape, from oval to lobed. Tiny inconspicuous flowers are clustered on small catkins. The easily bruised inch-long white fruit is less tasty than that of the red and black mulberries; fruit causes notorious stains. Numerous surface roots make the tree difficult to garden under. The white mulberry tree is subject to sooty canker and dieback. It tolerates heat, many different soils and coastal conditions. It likes full sun and regular water, but will take some drought. The tree easily hybridizes with other mulberries and many varieties are available, including weeping forms and contorted leaf specimens.

Mulberry fruit is enjoyed worldwide, especially in Asia. Wood, bark and leaves are used in commerce and for medicines and animal food. The Romans painted the trunks of their army elephants red with the juice to make them look fiercer. The soft leaves of M. alba have been used to feed silkworms for over 5,000 years; so long that Bombyx mori, the moth whose pupae provide 1,000 to 3,000 feet of silk each, has gone extinct in the wild. Seeds make the female, fruit-producing, white mulberry tree quite invasive in many parts of the country; fruitless (male) versions are not, but produce highly allergenic pollen.

--Pieter Severynen

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