Morus (plant)

Morus, a genus of flowering plants in the family Moraceae, consists of 19 species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 subordinate taxa, though the three most common are referred to as white, red, and black, originating from the color of their dormant buds and not necessarily the fruit color (Morus alba, M. rubra, and M. nigra, respectively), with numerous cultivars and some taxa currently unchecked and awaiting taxonomic scrutiny. M. alba is native to South Asia, but is widely distributed across Europe, Southern Africa, South America, and North America. M. alba is also the species most preferred by the silkworm. It is regarded as an invasive species in Brazil, the United States and some states of Australia.
The closely related genus Broussonetia is also commonly known as mulberry, notably the paper mulberry (Broussonetia papyrifera).
Despite their similar appearance, mulberries are not closely related to raspberries or blackberries. All three species belong to the Rosales order. But while the mulberry is a tree belonging to the Moraceae family (also including the fig, jackfruit, and other fruits), raspberries and blackberries are brambles and belong to the Rosaceae family.
Mulberries are fast-growing when young, and can grow to 24 metres (79 feet) tall. The leaves are alternately arranged, simple, and often lobed and serrated on the margin. Lobes are more common on juvenile shoots than on mature trees. The trees can be monoecious or dioecious.
The mulberry fruit is a multiple, about 2–3 centimetres (3⁄4–1+1⁄4 inches) long. Immature fruits are white, green, or pale yellow. The fruit turns from pink to red while ripening, then dark purple or black, and has a sweet flavor when fully ripe.
The taxonomy of Morus is complex and disputed. Fossils of Morus appear in the Pliocene record of the Netherlands. Over 150 species names have been published, and although differing sources may cite different selections of accepted names, less than 20 are accepted by the vast majority of botanical authorities. Morus classification is even further complicated by widespread hybridisation, wherein the hybrids are fertile.
The following species are accepted:
Black, red, and white mulberries are widespread in Southern Europe, the Middle East, Northern Africa, and the Indian subcontinent, where the tree and the fruit have names under regional dialects.
Black mulberry was imported to Britain in the 17th century in the hopes that it would be useful in the cultivation of silkworms. It was much used in folk medicine, especially in the treatment of tapeworms.
The United States has native red mulberries, as well as imported black and white mulberries. In North America, the white mulberry is considered an invasive exotic and has taken over extensive tracts from native plant species, including the red mulberry.
Mulberries are also widespread in Greece, particularly in the Peloponnese, which in the Middle Ages was known as Morea, deriving from the Greek word for the tree (μουριά, mouria).
Australia has two types of native mulberries: Hedycarya angustifolia, and Pipturus argenteus, which are both from different families to Moraceae. The exotic black, red and white Morus mulberries are also commonly grown in Australian backyards. White mulberry is considered an environmental weed in the states of Queensland and New South Wales.
Mulberries can be grown from seed, and this is often advised, as seedling-grown trees are generally of better shape and health. Mulberry trees grown from seed can take up to ten years to bear fruit. Mulberries are most often planted from large cuttings, which root readily. The mulberry plants allowed to grow tall have a crown height of 1.5 to 1.8 m (5 to 6 ft) from ground level and a stem girth of 10–13 cm (4–5 in). They are specially raised with the help of well-grown saplings 8–10 months old of any of the varieties recommended for rainfed areas like S-13 (for red loamy soil) or S-34 (black cotton soil), which are tolerant to drought or soil-moisture stress conditions. Usually, the plantation is raised and in block formation with a spacing of 1.8 by 1.8 m (6 by 6 ft), or 2.4 by 2.4 m (8 by 8 ft), as plant-to-plant and row-to-row distances. The plants are usually pruned once a year during the monsoon season to a height of 1.5–1.8 m (5–6 ft) and allowed to grow with a maximum of 8–10 shoots at the crown.
Mulberry tree scion wood can easily be grafted onto other mulberry trees during the winter, when the tree is dormant. One common scenario is converting a problematic male mulberry tree to an allergy-free female tree, by grafting all-female mulberry tree scions to a male mulberry that has been pruned back to the trunk. However, any new growth from below the graft(s) must be removed, as they would be from the original male mulberry tree.
All parts of the plant besides the ripe fruit can exude a milky sap (latex) which is mildly toxic if ingested, causing digestive distress and, at larger doses, hallucinations. It is also an irritant and may cause a skin rash on contact. Unripe green fruit may cause nausea, cramps, and be hallucinogenic. The berries have a laxative effect; too many will cause diarrhoea.
Some North American cities have banned the planting of mulberries because of the large amounts of pollen they produce, posing a potential health hazard for some pollen allergy sufferers. Only the male mulberry trees produce pollen; this lightweight pollen can be inhaled deeply into the lungs, sometimes triggering asthma. Conversely, female mulberry trees produce all-female flowers, which draw pollen and dust from the air. Because of this pollen-absorbing feature, all-female mulberry trees have an OPALS allergy scale rating of just 1 (lowest level of allergy potential), and some consider it "allergy-free".
Raw mulberries are 88% water, 10% carbohydrates, 1% protein, and less than 1% fat. In a 100-gram (3.5-ounce) reference amount, raw mulberries provide 43 calories, 44% of the Daily Value (DV) for vitamin C, and 14% of the DV for iron; other micronutrients are insignificant in quantity.
The leaves are harvested three or four times a year by a leaf-picking method under rain-fed or semi-arid conditions, depending on the monsoon. The leaves are useful as animal fodder. The tree branches pruned in the fall (autumn; after the leaves have fallen) are cut and used to make durable baskets supporting agriculture and animal husbandry.
As the fruit matures, mulberries change in texture and color, becoming succulent, plump, and juicy, resembling a blackberry. The color of the fruit does not distinguish the mulberry species, as mulberries may be white, lavender or black in color. The fruit of the black mulberry (native to southwest Asia) and the red mulberry (native to eastern North America) have distinct flavors. White mulberry fruits are typically sweet, but not tart, while red mulberries are usually deep red, sweet, and juicy. Black mulberries are large and juicy, with balanced sweetness and tartness. The fruit of the East Asian white mulberry – a species extensively naturalized in urban regions of eastern North America – has a different flavor, sometimes characterized as refreshing and a little tart, with a bit of gumminess to it and a hint of vanilla.
Mulberries are used in pies, tarts, wines, cordials, and herbal teas. Jams and sherbets are often made from the fruit in the Old World. In spring, new tender twigs are semisweet and can be eaten raw or cooked.
The fruit and leaves are sold in various forms as dietary supplements.
Mulberry leaves, particularly those of the white mulberry, are ecologically important as the sole food source of the silkworm (Bombyx mori, named after the mulberry genus Morus), the cocoon of which is used to make silk. The wild silk moth also eats mulberry. Other Lepidoptera larvae—which include the common emerald, lime hawk-moth, sycamore moth, and fall webworm—also eat the plant.
The Ancient Greeks and Romans cultivated the mulberry for silkworms; at least as early as 220 AD, Emperor Elagabalus wore a silk robe. English clergy wore silk vestments from about 1500 onwards. Mulberry and the silk industry played a role in colonial Virginia.
Mulberry fruit color derives from anthocyanins, which have unknown effects in humans. Anthocyanins are responsible for the attractive colors of fresh plant foods, including orange, red, purple, black, and blue. These colors are water-soluble and easily extractable, yielding natural food colorants. Due to a growing demand for natural food colorants, they have numerous applications in the food industry.
A cheap and industrially feasible method has been developed to extract anthocyanins from mulberry fruit that could be used as a fabric dye or food colorant of high color value. Scientists found that, of 31 Chinese mulberry cultivars tested, the total anthocyanin yield varied from 148 to 2725 mg/L of fruit juice. Sugars, acids, and vitamins of the fruit remained intact in the residual juice after removal of the anthocyanins, indicating that the juice may be used for other food products.
Mulberry germplasm resources may be used for:
During the Angkorian age of the Khmer Empire of Southeast Asia, monks at Buddhist temples made paper from the bark of mulberry trees. The paper was used to make books, known as kraing.
Tengujo is the thinnest paper in the world. It is produced in Japan and made with kozo (stems of mulberry trees). Traditional Japanese washi paper is often created from parts of the mulberry tree.
The wood of mulberry trees is used for barrel aging of Țuică, a traditional Romanian plum brandy.
A Babylonian etiological myth, which Ovid incorporated in his Metamorphoses, attributes the reddish-purple color of the mulberry fruits to the tragic deaths of the lovers Pyramus and Thisbe. Meeting under a mulberry tree (probably the native Morus nigra), Thisbe commits suicide by sword after Pyramus does the same, he having believed, on finding her bloodstained cloak, that she was killed by a lion. Their splashed blood stained the previously white fruit, and the gods forever changed the mulberry's colour to honour their forbidden love.
In the Old Testament's 1 Maccabees, the Seleucids used the "blood of grapes and mulberries" to provoke their war elephants in preparation for battle against Jewish rebels.
The nursery rhyme "Here We Go Round the Mulberry Bush" uses the tree in the refrain, as do some contemporary American versions of the nursery rhyme "Pop Goes the Weasel".
Vincent van Gogh featured the mulberry tree in some of his paintings, notably Mulberry Tree (Mûrier, 1889, now in Pasadena's Norton Simon Museum). He painted it after a stay at an asylum, and he considered it a technical success.