Mulberry Family (Moraceae)

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Mulberry Family (Moraceae)

Ecology, distribution and economic value

The mulberry family occurs primarily in tropical and semi-tropical regions, and includes a wide variety of herbs, shrubs, and trees, characterized by a milky sap and reduced, unisexual flowers. This family includes 40 genera and 1,000 species, of which 500 species are members of the fig genus, Ficus. The Moraceae is a member of the order Urticales, class Magnoliopsida (the dicotyledons), division Magnoliophyta (flowering plants).

Flowers, fruits and leaves

Species of the mulberry family may be either monoecious or dioecious, depending on whether male and female flowers occur on the same plant (monoecious) or on separate plants (dioecious). Flowers of the Moraceae are in tightly packed groups, known as heads, spikes, catkins, or umbels. Fig flowers are produced inside a synconium, a hollow fleshy structure. The small flowers lack petals. Male flowers consist of four sepals, which are usually leaf like appendages, and four stamens. Female flowers consist of four sepals and a pistil with a two-chambered ovary.

The fruit developed from a single female flower is either a fleshy drupe or a dry achene. The flowers fuse as they mature after fertilization, and a multiple fruit forms. The multiple fruit consists of small drupes or achenes grouped together in a single unit, and is usually round or oval shaped.

The best known fruit of the Moraceae is that of the common fig (Ficus carica ), which has been cultivated for thousands of years. These cultivated figs develop without pollination, as this species does not produces male flowers. It is actually the synconium that is referred to as the fruit of the fig. In the case of fig varieties which are pollinated, the true fruit, an achene, develops inside the synconium. Figs are pollinated by wasps.

A wild form of the common fig, known as the caprifig, does produce male flowers. Pollen of the caprifig is sometimes used by fig breeders to fertilize female flowers of cultivated figs. In this process, known as caprification, a female gall wasp, carrying pollen from the caprifig, enters the synconium of a cultivated fig, where she pollinates the flowers, lay eggs, dies, and is absorbed by the synconium as the fruit develops. Figs produced by caprification are usually larger than cultivated fig fruits.

The fruits of some Moraceae, such as those from the jackfruit (Artocarpus integra ), are very large, and can be up to 3 ft (1 m) long and weigh up to 99 lb (45 kg), although 44-55 lb (20-25 kg) is more common. Jackfruit leaves are much smaller than the fruits, usually 1.6 in (4 cm) or less.

Moraceae leaves occur in a variety of shapes and sizes. For example, breadfruit, (Artocarpus communis ), has lobed leaves that reach 2 ft (61 cm) in length. The common fig also has deeply lobed leaves. Other species, such as the creeping fig (Ficus pumila ), have cordate leaves that are much smaller, with entire margins. It is not unusual to find both lobed and unlobed leaves on the same plant, especially in mulberries (Morus spp.). Leaves can occur singly on the stem, on alternating sides. At the base of a young leaf’s petiole is a pair of stipules, but these soon fall off and leave a small scar on the stem.

Species of the Moraceae may be evergreen, or they may have deciduous leaves that fall off at the end of the growing season.

Ecology, distribution and economic value

The family Moraceae was named after the mulberry, Modus. The red mulberry, Modus rubra, is native to North America, where it occurs in moist woodlands. It produces a tasty, juicy fruit which is favored by birds, and although it is also good for people to eat, it is not economically important. The white mulberry, Modus alba, is native to Asia. In China, leaves of the white mulberry are fed to cultivated silkworms, a type of moth larva. The white mulberry became naturalized in North America during unsuccessful attempts to establish a silk industry in colonial America. Unlike the native red mulberry, the white mulberry is somewhat weedy, and is often found around homes, in disturbed sites, along fencerows, and in moist, second-growth bottomlands. Fruits of the white mulberry may be white, pink, red, or deep purple. The dark purple fruits inspired the name Modus nigra, although taxonomists have since determined this plant to only be a variety of Modus alba.

Similar in appearance to white mulberry, and also naturalized in the United States, is the ornamental shrub, paper mulberry (Broussonetia papyrifera ), also native to Asia. This mulberry is shrubby, and may form thick colonies from root sprouts. Paper mulberry occurs around homes, fencerows, and disturbed sites. The bark of the paper mulberry is the source of tapa, a fiber used by Pacific islanders to make clothing.

The osage-orange, (Maclura pomifera ), is a shrubby tree native to the Red River Valley of Texas, Oklahoma, and Arkansas. Like the mulberries, this species can propagate from root sprouts. The osage-orange is a thorny tree that bears a spherical, multiple fruit composed of achenes. The wood of this species is orange in color, and very strong. This wood was used by Native Americans to manufacture bows, and by early pioneers to make long-lasting fence posts and wagon wheels.

The genus Artocarpus includes the breadfruit and jackfruit, whose fruits are used in the Caribbean and South Pacific as food. As the name breadfruit implies, the fruit is starchy, when cooked similar in texture and taste to potatoes. Many tourists have eaten breadfruit while vacationing in the Caribbean, unaware that it was not potatoes. Breadfruit, native to parts of Asia and tropical Pacific islands, was to be brought to the Caribbean islands by Captain Bligh, of Bounty fame.

Species of the diverse fig genus, Ficus, take an assortment of forms. Some of the more unusual species include the strangler figs such as the banyan tree (Ficus benghalensis ), which begins life as an epiphyte and sends down rope-like roots that eventually encircle and kill the host tree. A mature banyan tree is an impressive sight, with its large, spreading canopy, and numerous supporting trunks, often encircling a hollow cavity where the original host tree stood. The banyan tree is native to India, where it is considered sacred by Hindus. The bo tree, (Ficus religiosa ), of India is believed to bring wealth and happiness to its owners. The bo tree is also considered sacred by Hindus, who believe their god Vishnu was born under one, and to Buddhists, who believe Gautama Buddha achieved nirvana while meditating under one of these trees.

Other important members of the fig genus are some popular horticultural species. The weeping fig, (Ficus benjamina ), can be grown in pots into a small attractive tree with willowy branches and leaves. This species prefers bright light, moist soil, and a humid environment. The fiddleleaf fig, (Ficus lyrata ), is a shrub with large leaves shaped like fiddles. The sap of the Indian rubber plant, (Ficus elastica ), was once used to manufacture rubber. This species reaches tree proportions when cultivated as an ornamental in southern Florida.

KEY TERMS

Achene —A dry, indehiscent, one-seeded fruit, with the outer layer fused to the seed.

Cordate —Heartshaped.

Naturalized —A nonnative species which has become freely breeding beyond its natural range.

Synconium —The hollow, fleshy structure in figs which houses the flowers and is often incorrectly referred to as the fruit. The true fruit often has the achenes borne inside the synconium on the female flowers.

Unisexual —Flowers that bear either male or female reproductive organs.