Morus alba, known as white mulberry, is a fast-growing, small to medium-sized mulberry tree which grows to 10–20 m (33–66 ft) tall. It is generally a short-lived tree with a lifespan comparable to that of humans, although there are some specimens known to be over 250 years old.^[2] The species is native to northern China and India^[3], and is widely cultivated and naturalized elsewhere (United States, Mexico, Australia, Kyrgyzstan, Argentina, Turkey, Iran, etc.).^{[4][5][6][7][8][9]}

The white mulberry is widely cultivated to feed the silkworms employed in the commercial production of silk. It is also notable for the rapid release of its pollen, which is launched at over half the speed of sound.^[10] Its berries are edible when ripe.

Description

On young, vigorous shoots, the leaves may be up to 30 cm (12 in) long, and deeply and intricately lobed, with the lobes rounded. On older trees, the leaves are generally 5–15 cm (2.0–5.9 in) long, unlobed, cordate at the base and rounded to acuminate at the tip, and serrated on the margins. The trees are generally deciduous in temperate regions, but trees grown in tropical regions can be evergreen. The flowers are single-sex catkins; male catkins are 2–3.5 cm (0.8–1.4 in) long, and female catkins 1–2 cm (0.4–0.8 in) long. Male and female flowers are usually on separate trees although they may occur on the same tree.^[11][12] The fruit is 1–1.5 cm (0.4–0.6 in) long; in the species in the wild it is deep purple, but in many cultivated plants it varies from white to pink; it is sweet but bland, unlike the more intense flavor of the red mulberry and black mulberry. The seeds are widely dispersed in the droppings of birds that eat the fruit.^[4][5][13]

The white mulberry is scientifically notable for the rapid plant movement involved in pollen release from its catkins. The stamens act as catapults, releasing stored elastic energy in just 25 µs. The resulting movement is approximately 350 miles per hour (560 km/h), over half the speed of sound, making it the fastest known movement in the plant kingdom.^[10]

Taxonomy

Two varieties of Morus alba are recognized:^[4]

• Morus alba var. alba
• Morus alba var. multicaulis

Cultivation

Cultivation of white mulberry for silkworms began over four thousand years ago in China. In 2002, 6,260 km² of land were devoted to the species in China.^[5]

The species is now extensively planted and widely naturalized throughout the warm temperate world. It has been grown widely from the Indian subcontinent^[5] west through Afghanistan and Iran to southern Europe for over a thousand years for leaves to feed silkworms.^[13]

More recently, it has become widely naturalized in disturbed areas such as roadsides and the edges of tree lots, along with urban areas in much of North America, where it hybridizes readily with the locally native red mulberry (Morus rubra). There is now serious concern for the long-term genetic viability of the red mulberry because of extensive hybridization in some areas.^[14]

Uses

Mulberry leaves placed on trays with silkworms (Liang Kai‘s Sericulture c. 1200s)Ppongnip-cha (mulberry leaf tea)

White mulberry leaves are the preferred feedstock for silkworms, and are also cut for food for livestock (cattle, goats, etc.) in areas where dry seasons restrict the availability of ground vegetation. The leaves are prepared as tea in Korea. The fruit are also eaten, often dried or made into wine.^[5][13]

For landscaping, a fruitless mulberry was developed from a clone for use in the production of silk in the U.S. The industry never materialized, but the mulberry variety is now used as an ornamental tree where shade is desired without the fruit.^[15] A weeping cultivar of white mulberry, Morus alba ‘Pendula’, is a popular ornamental plant.^[16] The species has become a popular lawn tree across the desert cities of the southwestern United States, prized for its shade and also for its cylindrical berry clusters composed of sweet, purplish-white fruits.^[17] The plant’s pollen has become problematical in some cities where it has been blamed for an increase in hay fever.^[18][19][20]

Medicinal

Dental caries: The root bark of Morus alba (Moraceae) has been used as a traditional medicine in Asian countries and exhibits antibacterial activity against food poisoning micro-organisms.^{[citation needed]} Using activity against S. mutans in bioassay-guided fractionation of a methanol extract of dried root bark, and organic solvent fractions of this extract, the active antibacterial constituent was identified as kuwanon G. The compound displayed an MIC of 8 μg ml–1 against S. mutans, which was comparable to chlorhexidine and vancomycin (1 μg ml–1). Time-kill assays indicated that S. mutans was completely inactivated by 20 μg ml–1 kuwanon G within 1 min, while testing against other bacteria suggested that the compound displayed preferential antimicrobial activity against cariogenic bacteria. Electron microscopic examination of S. mutans cells treated with kuwanon G indicated that the mode of antibacterial action was inhibition or blocking of cell growth, as treated cells showed a disintegrated surface and an unclear cell margin.^[21]

Hypolipidemic and antioxidant effects from freeze-dried powder of mulberry (Morus alba L.) fruit^[22]

Neuroprotective effects in in vitro and in vivo (fruit)^[23]

Albanol A, isolated from the root bark extract of M. alba, may be a promising lead compound for developing an effective drug for treatment of leukemia.^[24]

Moracin M, steppogenin-4′-O-β-D-glucoside and mulberroside A were isolated from the root bark of Morus alba L. and all produced hypoglycemic effects.^[25] Mulberroside A, a glycosylated stilbenoid, can be useful in the treatment of hyperuricemia and gout^[26][27]

A methanol extract of Morus alba roots showed adaptogenic activity, indicating its possible clinical utility as an antistress agent.^[28]

Morus alba leaf extract help restore the vascular reactivity of diabetic rats. Free radical-induced vascular dysfunction plays a key role in the pathogenesis of vascular disease found in chronic diabetic patients.^[29]

An ethanolic extract of mulberry leaf had antihyperglycemic, antioxidant and antiglycation effects in chronic diabetic rats, which may suggest its use as food supplement for diabetics.^[30]

Extract from the plant’s leaf has also been shown to be useful as an antivenom agent:

Morus alba plant leaf extract has been studied against the Indian Vipera/Daboia russelii venom induced local and systemic effects. The extract completely abolished the in vitro proteolytic and hyaluronolytic activities of the venom. Edema, hemorrhage and myonecrotic activities were also neutralized efficiently. In addition, the extract partially inhibited the pro-coagulant activity and completely abolished the degradation of A α chain of human fibrinogen. Thus, the extract processes potent antisnake venom property, especially against the local and systemic effects of Daboia russelii venom.^[31]

From Wikipedia, the free encyclopedia