David Gress
Morus alba
White Mulberry is an attractive fast-growing, medium-sized, tree that can reach 50 feet in height – although in our community it usually only reaches about 30 to 40 feet with a spread of 25 to 30 feet.
For more than 4,700 years in China, it has been grown principally to provide the primary food of silkworm caterpillars, which then spin cocoons of silk fibers used in the production of beautiful silk fabric. So, one could say that the White Mulberry is the source of the ancient “Silk Road” trade route to the Far East!
In the 1700s, a fruitless cultivar of White Mulberry, named (not surprisingly) “Fruitless White Mulberry”, was developed, selected, and propagated for silk production in this country, and today is now the variety most used for landscaping.
After a brief period in winter when the tree is deciduous (bare of leaves), in spring its broad rounded canopy is covered with dense green foliage that is composed, initially, of light-green, heart-shaped or lobed leaves. Later leaves are richly dark-green, leathery, and ovate (2- to 7-inches long) with one or more deep lobes and serrated edges. On the top, the mature leaves are smooth and glossy; on the underside, they are sometimes hairy with distinctively prominent veins. When cut, they exude a white sap. In the fall, they turn bright yellow
Fruitless White Mulberry, bearing no seeds, requires propagation either by stem cuttings from another Fruitless White Mulberry or by grafting – and will remain a genetically identical clone.
Most other varieties and cultivars of mulberry are fruiting; they bear an abundance of delicious and nutritious berries. The fruiting types are, generally, planted in private gardens – and are, certainly, planted in fruit orchards.
Fruiting mulberry trees are usually “dioecious”, which means male flowers and female flowers occur on separate trees – but some varieties are “monoecious”, which means both male flowers and female flowers occur on a single tree. In either case, in March through May, yellow-green, inconspicuous, tiny flowers form on drooping spikes, called “catkins” (1- to 2-inches long).
In fruiting varieties, the male flowers produce abundant pollen that is catapulted from the stamens at the astonishing speed of approximately 380 MPH! The female flowers develop into clusters of small fruits that are similar to raspberries. The berries can be white, pink, or deep purple and are delightfully sweet but, surprisingly, otherwise lacking in flavor. The berries are very attractive to voracious squirrels and hungry birds; through them, the seeds are widely spread, along with a dollop of fertilizer. Those berries not eaten fall to the ground and create a messy stain on hard surfaces; consequently, fruiting varieties should not be planted in high use areas.
The bark of White Mulberry is tan to light gray in color and with age will develop shallow vertical fissures to reveal an even lighter orange-brown bark beneath; this is an attractive ornamental feature, especially in winter when the tree is bare.
The White Mulberry is endemic to China and India. It is in the Moraceae (Mulberry) plant family. Its botanical name is Morus alba. The genus name, Morus, is the Latin name for “mulberry tree”; the specific epithet, alba, is Latin and means “white”. Other common names for White Mulberry are “Common Mulberry” and “Silkworm Mulberry”.
White Mulberry is easy to grow here and is low maintenance, except for occasional pruning needed due to its fast growth when young. Its native areas generally receive far more rain than we do, so additional watering is needed here for it to look its best. It grows well in full sun but can tolerate partial shade. It can be planted in all types of soil but prefers a well-drained deep sandy loam. Keep in mind that, as it ages, it will develop surface roots that can interfere with hardscaping and lawns.
As noted, White Mulberry is cultivated worldwide as a food source for silkworms in silk production. Traditionally, mulberry leaves and bark are used to brew teas and are used in Chinese medicine to treat a variety of medical conditions. However, they do contain toxins, so proper processing is first required. Mulberry wood has been used to produce furniture, tools and utensils. Mulberry fruit is highly perishable, so in addition to being eaten fresh, it can be preserved by drying, or processed into syrups, wines, and distilled beverages.
Fruitless White Mulberry (Morus alba ‘Fruitless’) is a delightful ornamental tree, useful for its attractive foliage and shade-producing broad canopy, and without messy fruit – valuable features for planting in parks, in private gardens, and on commercial grounds. The distinctive fruiting cultivar, “Weeping Mulberry” (Morus alba ‘Pendula’), is a striking specimen and creates a focal point in any landscape.
White Mulberries can be seen around town as a street tree at 821 Anza Drive; as park trees in Skofield Park, Mackenzie Park, Bohnett Park, and La Mesa Park; and in commercial and private landscapes in the parking lots behind 1302 and 1330 State Street, and at 1313 East Gutierrez Street.
Tree-of-the-Month articles are sponsored by Santa Barbara Beautiful, whose many missions include the increase of public awareness and appreciation of Santa Barbara’s many outstanding trees and, in a long-time partnership with the City Parks & Recreation Department, the funding and planting of trees along the City’s streets.
Those who wish to honor a special someone can do so with an attractive commemorative marker that will be installed at the base of an existing street tree in the City of Santa Barbara. Because Santa Barbara Beautiful has participated in the planting to date of over 14,000 street trees, there are plenty of trees from which to choose! Application forms are available on the Santa Barbara Beautiful website, www.sbbeautiful.org. This website also contains an archive of all previously published Tree-of-the-Month articles, including photos.
Always interesting.