1. Unusual Fruits of the Mulberry Family
   
2. The Remarkable Genus of Figs (Ficus)
   
3. Which Figs Grew in the Holy Land?
   
4. The Black Mulberry (Morus nigra)
   
5. Does Black Mulberry Stain Clothing?
   
6. The White Mulberry (Morus alba)
   
7. The Pakistan Mulberry (Morus macroura)
   
8. Silk From Moth That Eats Mulberry Leaves
   
9. References From Economic Botany Page

Other interesting multiple fruits in the mulberry family are jackfruit (Artocarpus heterophyllus), breadfruit (Artocarpus altilis) and osage orange (Maclura pomifera). For more information about these fascinating fruits, click on the links below. Other multiple fruits include the pineapple and a large-leaved relative of the houseplant called philodendron. The pineapple is a multiple fruit in the bromelia family (Bromeliaceae), and the aroid Monstera deliciosa is a multiple fruit in the arum family (Araceae).

Mulberry fruits are eaten raw and made into pies, tarts, jellies, puddings, syrups, sauces, drinks and wines. Dried fruits are used like dried figs and raisins for snacks and in puddings, cookies, muffins and confections. There are numerous cultivated varieties and hybrids of red, white and black mulberries. In fact, Stephen Facciola (Cornucopia II: A Source Book of Edible Plants, 1998) lists 28 cultivars of Morus alba, M. nigra and M. rubra.

Most genera in the Moraceae are wind-pollinated by male (staminate) flowers. Many species are dioecious with male and female flowers on separate male and female trees. In monoecious species with male and female flowers on the same tree, pollination typically requires pollen from a different tree because the maturation sequence of male and female flowers on the same tree is incompatible. The ripened ovary (technically a bicarpellate gynoecium) usually contains one seed within a single locule. Each minute fruit has an outer fleshy layer (exocarp and mesocarp) and a stony inner layer (endocarp) surrounding the seed. For this reason the individual fruits are often called drupelets, although some authors refer to them as achenes. Some species and varieties produce fleshy, seedless fruits without pollination. These fruits are called parthenocarpic because they mature without pollination and seed formation.

Many species of trees in the mulberry family have a milky latex sap and stringy bark that peels off into strips. The milky sap of the Central American milk tree (Brosimum utile) is actually edible. Known as "palo de vaca" to the locals, the fresh sap is sweet and tastes like cream. In fact, it has been used in coffee and to make "vegetable cheese" in British Guiana. The breadnut (B. alicastrum) is also used for food by local people and was an important food tree in the Maya civilization of Mexico and Central America. The seeds are eaten raw, boiled, or mashed like potatoes. Ground seeds are made into a meal that is mixed with corn for making tortillas. The ground seeds are also made into a coffee-like beverage and mixed with milk and sugar to make a drink similar to a milk shake.

The pliability and usefulness of the bark of mulberries and related trees of the Moraceae is due to clusters of bast fibers in the inner phloem region. For countless centuries, native people throughout the world have used the stringy bark to make twine, paper and clothing called "bark cloth." Mexican bark paper is still being made to this day, particularly in the state of Puebla. The fibrous inner phloem fibers are separated from the outer bark in strips and boiled for several hours in water containing lime. This procedure softens the fibers and makes them separate more easily. After rinsing, the strips are arranged in a grid pattern on a smooth board and then beaten with a flattened stone until the fibers mesh together. The sheets are left on the boards and allowed to dry in the sun. The bark of several tree species are used, including a fig (Ficus tecolutensis) and a mulberry (Morus celtidifolia). A yellow dye from mulberry wood chips is used by the Mayo people for dyeing wool and other fabrics. It is also blended with other natural dye stuffs.

A process similar to that of bark paper can also be used as a substitute for cloth. The best known bark cloth is called tapa cloth, which was a major source of clothing for native Polynesians. The bark was obtained from the paper mulberry (Broussonetia papyrifera), a member of the mulberry family (Moraceae). Native figs, such as the Polynesian banyan (Ficus prolixa) were also used locally on some islands for bark cloth. Strips of bark were peeled off the trunk, and the outer coating scraped off with a shell. After they were soaked in water and cleaned, the strips were placed on a hard wood surface and pounded with a mallet. Individual strips were fused together by overlapping the edges and beating them together. Depending on the thickness of the sheets, the finished tapa cloth varied in appearance from a muslin-like material to a tough, leather-like cloth.

One of the earliest records of any fruit eaten by people of the Middle East is the common fig (Ficus carica). Remnants of figs have been found in archeological excavations dating back 6,000 years ago. The fig is the first tree mentioned in the Bible in the story of Adam and Eve. Some biblical scholars think the fig, and not the apple, was the forbidden fruit picked by Eve in the Garden of Eden. Chauvinistic males also believe the penalty for this unauthorized fruit-picking was a sorrowful menstrual cycle. The scratchy leaves of this tree were reportedly used to cover the genitalia of the first humans. The fig is native to Caria--an ancient region of Asia Minor between the Mediterranean and Black Seas. It grows readily from seeds and cuttings, especially along water courses and rich, bottom lands, and was introduced by people throughout the Holy Land. Fig trees provided shade, fire wood and several crops of nourishing fruit a year. Dried figs could be squeezed into loaves or placed on strings and used as food during long, arduous journeys across the desert.

The common fig (Ficus carica) is a dioecious species with male and female trees. A tiny female wasp (Blastophaga psenes) enters an opening on the syconium to pollinate the flowers. In F. carica, only the syconia of female trees are edible, and without pollination they typically do not ripen and fall from the branches. [Note: There are many parthenocarpic varieties in which the seedless syconia ripen without pollination.] Male trees, called caprifigs, produce inedible syconia containing short-style female flowers bearing wasps and pollen-laden male flowers. [Capri refers to goat and the syconia were apparently fed to livestock.] During the late 1800s, Calimyrna fig growers in California were puzzled why their trees would not set fruit. They discovered that the female trees needed the fig wasp and male caprifigs from the Old World. Each June in California's hot Central Valley, bags of wasp-bearing caprifigs are placed in the Calimyrna orchards. This amazing pollination process is called caprification and the crunchy, seed-bearing syconia of female trees have a superior nutty flavor. [Premium fig newtons are made from caprified figs and contain numerous seed-bearing nutlets or endocarps.]

The black mulberry (Morus nigra) is a dioecious tree native to western Asia. The bumpy surface of the fruit is due to many tightly-packed, seed-bearing ovaries (drupelets), each with separate styles that appear like black hairs. It is technically a multiple fruit (called a syncarp) composed of a cluster of drupelets superficially resembling a blackberry (Rubus) of the rose family (Rosaceae); however, unlike a blackberry, each drupelet arises from a separate, minute, unisexual (female) flower. Individual flowers do not have petals, but have a calyx composed of four minute sepals. The inconspicuous sepals are closely appressed to the ovary, but are visible under 10x magnification. Mulberry flowers are produced in catkins, typically with male and female catkins on different trees. Male flowers have four stamens while female flowers have a single pistil (gynoecium). In the aggregate fruit of a blackberry, all the drupelets of the cluster (syncarp) come from a single bisexual flower with a ring of many stamens surrounded by five white petals.

NYBG Steere Herbarium Definition of Gynodioecious: Sexual condition of a species that bears pistillate flowers on some plants and bisexual flowers or staminate flowers as well as pistillate flowers on other plants. The important word here is "or" rather than "and" [e.g. Fig (Ficus) & Mulberry (Morus)].

Leaves of the Chinese white mulberry (Morus alba) and the black mulberry (M. nigra) provide the primary food source for larvae of the silkworm moth (Bombyx mori). The larva feeds on mulberry leaves for about 45 days until it reachs a length of two inches (50 mm). At maturity, the larva spins a cocoon around itself and changes into a pupa, a process known as metamorphosis. The proteinaceous silk filament used to spin the cocoon is secreted from modified salivary glands in the mouth. [Note: Butterflies typically do not spin a coccon and their mummy-like pupa is called a chrysalis.] Silk thread is unwound from silkworm cocoons placed in hot water. In fact, the discovery of silk dates back at least 4,000 years to the Chinese empress Si-ling. According to one story, the empress accidently dropped a cocoon into a cup of hot tea and discovered the strands of the cocoon became loose and unraveled between her fingers. She tried weaving this natural fiber into cloth, and her experimentation eventually lead to the commercial rearing of silkworms (called sericulture) and the silk industry. For centuries, merchants exported this luxurious and valuable textile across vast regions of Asia in silk caravans. Mulberry trees were gradually introduced into European countries by the time of the Roman Empire, but China and Japan continue to produce 75 percent of all the silk in the world today. Most of the silk produced in India is made into saris, while the kimono accounts for nearly 90 percent of all the silk used in Japan. Silk for the famous wedding dress worn by Diana, Princess of Wales was spun by silkworms raised at Britain's silk farm near Sherborne in Dorset.

In San Diego County, Mulberry street in San Marcos was once the site of a mulberry grove planted for silkworm culture during the 1920s. 45,000 mulberry trees were planted in 1926, and eventually the orchard contained more than 100,000 trees. The original San Diego County Silk Company (later called the American Silk Factories) was located along Mission Road, in a large building later occupied by the Teledyne Aero-Cal Company. The San Marcos silk industry collapsed with the stock market crash of 1929 and the perfection of a silk substitute called rayon by the DuPont Chemical Company.

Tussah silk is spun in India and Pakistan from the cocoons of wild silk-producing larvae which feed of "sal" trees (Shorea) in the Diptocarpaceae. The resinous sap of large rainforest trees of the genus Shorea are also the source of dammar resins. Dammars are East Indian and southeast Asian resins similar to copals. Like copals they are shiny and transparent when dry and are used extensively in the paint and varnish industry. Another creamy white or reddish silk called "Eri" is produced from larvae that feed on castor bean plants (Ricinus communis) of the Euphorbiaceae.

In Japan, genetically engineered silkworms containing the gene for human collagen spin their cocoons with silk thread containing this vital protein. Collagen is a component of fibrous connective tissue and is found in skin, tendons, ligaments and bones. In fact, the thickening agent or hydrogel called Gelatin® is made from denatured collagen by boiling animal connective tissues in water. Collagen can now be chemically extracted from silk, providing an economical source of this valuable protein. Pharmaceutical companies hope to harvest human collagen for many applications, including artificial skin and wound dressings.

A single silkworm cocoon may contain more than 3,000 feet (1 km) of continuous filament. Depending on the reference, other estimates range from 1,000 feet to 3,000 yards per cocoon. The exact length is probably somewhere in between these extremes. While most plant fibers are cellulose polymers composed of many glucose subunits linked together, silk is a polypeptide polymer composed of amino acid subunits. This fundamental chemical difference explains why plant and animal fibers react differently to heat, chemical dyes, water and predatory insects. Compared with cotton, silk fibers are less absorbent to water and are subject to denaturation by heat; however, silk fibers generally accept permanent dyes more readily and are more elastic. Raw silk actually consists of two proteins, fibroin and sericin. The fibers are very fine and lustrous, about 1/2500th of an inch in diameter. About 2,000 to 3,000 cocoons are required to make a pound of silk. Based on 2/3 of mile (1 km) per cocoon, ten unraveled cocoons could theoretically extend vertically to the height of Mount Everest, the world's highest mountain. It is estimated that at least 100 million pounds of raw silk are produced each year, requiring nearly 10 billion pounds of mulberry leaves. According to E. L. Palmer (Fieldbook Of Natural History, 1949), one pound of silk represents about 1,000 miles of filament. The annual world production represents 70 billion miles of silk filament, a distance well over 300 round trips to the sun!

Go To Identification Of Major Fruit Types To Economically Important Plant Families Return To WAYNE'S WORD Home Page Return To NOTEWORTHY PLANTS Page Go To Biology GEE WHIZ TRIVIA Page Go To The LEMNACEAE ON-LINE Page