Morus alba. WHITE MULBERRY. China
M. nigra. BLACK MULBERRY. W. Asia
M. rubra. RED MULBERRY. Eastern N. America
MORACEAE (Mulberry family)

A deciduous tree whose leaves, the food of the silkworm, have rounded teeth and may be deeply lobed, or may have no lobes at all. Several varieties of fruitless mulberries are available. Specimens may be seen at the south wall of the Old Union Clubhouse (four), at the east end of Mitchell Earth Sciences (several), in the courtyard of the Ginzton Laboratory on Via Palou, and on Escondido Road heading west from Campus Drive East. Those in the lawn east of Wilbur Hall, which were planted in 1955, have massive, conspicuous surface roots. The leaves are generally large, generously lobed, and glossy on top.

If you have mulberry leaves you can grow silkworms, which is fun for youngsters as first the worms and then the moths do their own thing. And, if you grow your own silkworms, you can make silk. One silkworm produces about half a mile of incredibly strong monofilament that is routinely reeled without a break from the cocoon. Vast sums were invested to no account to introduce silk production into Britain, and in Virginia mulberry planting was at one time required by law. Several million trees were planted in California before 1900. No luck; raw silk still has to be imported from Japan, China, or Russia. Native silkworms, such as feed on the tulip tree of the Eastern states, were also considered. A steel wire of the same diameter as a silk thread (3 microns) breaks under less load than silk can carry; in addition, steel cannot be stretched much more than 1 percent without breaking, while silk can stretch 20 percent before breaking. Such extreme physical properties permit an Australian rainforest spider Nephila to catch small birds and bats in its web. To make silk, the secret of success of spiders in this world, is not easy. Before rebuilding its web, a spider finds it necessary to recycle the used silk by eating it.

The pale mulberries are not as good to eat as the deep purple ones of the black mulberry M. nigra (leaves dull green above and furry below) but the only one on campus is in the back lawn of 582 Alvarado Row (Bolivar House), formerly the home of V.P. Twitty. While there look at the unique Cryptomeria japonica 'Elegans.'

The venerable mulberry planted in 1889 in the outer northeast island of the Inner Quad is an American red mulberry M. rubra, as witnessed by the small, rough-topped leaves that are paler below and with hairy veins.

Illustrations (links open new windows): M. rubra leaf detail (Inner Quad); M. rubra branchlet; Silhouettes from Trees of Stanford & its Environs


Name derivation, genus | species Latin name for mulberry tree

Related material: Canopy Trees for Palo Alto Tree Library

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