Mulberry is a compound that commits a cheerful etymological redundancy. Old English mōrberie combines Latin morum (mulberry, from Greek moron) with Old English berie (berry), producing a word that literally means mulberry-berry. The Anglo-Saxons, encountering the Latin name for the fruit, apparently didn't recognize morum as already meaning berry and helpfully added their own word to clarify. This type of tautological compound — where the same meaning is expressed twice in different languages — is surprisingly common in English (cf. River Avon, which means River River).
German Maulbeere commits the same redundancy with the same structure. French mûre, Italian mora, and Spanish mora all derive from the Latin morum without the added berry, making the English and German forms the odd ones out.
The mulberry's cultural significance extends far beyond its fruit. The white mulberry (Morus alba) is the sole food source of the silkworm (Bombyx mori), making it one of the most economically important trees in human history. Chinese silk production — which for millennia was a closely guarded state secret — depended entirely on mulberry cultivation. The Silk Road itself might more accurately have been called the Mulberry Road, since without mulberry trees, there would have been no silk to trade
Chinese authorities maintained their silk monopoly for roughly three thousand years by making the export of silkworm eggs or mulberry seeds a capital offense. The secret was broken, according to legend, when Byzantine Emperor Justinian I sent monks to China in 552 CE who smuggled silkworm eggs back to Constantinople hidden in hollow walking sticks.
In England, James I attempted to establish a domestic silk industry in the early 17th century by ordering the planting of mulberry trees. Unfortunately, he planted black mulberries (Morus nigra) rather than the white mulberries that silkworms actually eat, dooming the enterprise. Several of James's mulberry trees survive in English gardens, producing excellent fruit if useless silk.
The nursery rhyme 'Here We Go Round the Mulberry Bush' preserves the tree in children's culture, though the connection between the rhyme and any actual mulberry bush is obscure. Some historians have linked the rhyme to the exercise yard at Wakefield Prison, where inmates supposedly walked around a mulberry bush for their daily exercise.