Broussonetia papyrifera Seeds | Paper Mulberry
LATIN NAME: Broussonetia papyrifera
COMMON NAME: Paper Mulberry
Plant Profile
Paper mulberry is heterophyllous, which is to say a single tree carries two kinds of leaf. Shade leaves and the leaves of young shoots are deeply lobed, often with three or five fingers; leaves in full sun on mature wood are usually entire and heart-shaped. All of them are rough to the touch on the upper surface and felted with white down beneath, and every part of the plant bleeds a milky latex when cut.
The species is dioecious, with male and female flowers on separate trees. Male trees hang loose catkins six to ten centimetres long that shed clouds of pollen; female trees carry tight round heads with protruding stigmas, which ripen into a soft orange-red syncarp two or three centimetres across. Each seed sits in a fleshy pocket within that compound fruit, and birds, bats and small mammals strip the crop as soon as it colours, which is one reason the tree spreads so effectively along roads and river banks.
Because it was planted for decades as a fast shade and street tree, paper mulberry now produces spring pollen in cities where nothing eats it. In several such cities its pollen ranks among the most irritating of the season, and the male trees are the source. Check the sex of any tree when it first flowers and remove males from gardens and school grounds if the area already carries a heavy load.
Because it produces a great deal of leaf and stem in a single season and roots deeply, paper mulberry has been trialled in the rehabilitation of degraded and metal-contaminated soils, and it is often one of the first woody plants to establish on mine spoil and raw road cut. That vigour is the same quality that makes it hard to control, so any use on damaged ground should be planned with its suckering habit in mind.
Science & Biotechnology
The root bark carries prenylated flavonols, among them the compound recorded as papyriflavonol A, together with the group of phenolics known as broussonins; the leaves hold related flavonoids and the fruit its own distinctive set. Extracts from these parts appear in published work on antibacterial and antioxidant activity, and the fruit extract has found its way into cosmetic formulations aimed at tired skin.
Uses & Benefits
Fibre is taken from canes of a single growth cycle. The stems are cut, steamed or soaked until the bark slips, and the dark outer bark is scraped away; what is kept is the inner bast, whose fibres run the full length of the stem without a break. Those long fibres are the whole point. Cleaned bast is boiled with an alkali, rinsed, and beaten until the fibre bundles separate into a fine suspension, then formed into sheets on a screen with the help of a natural mucilage stirred into the vat, which holds the fibres in suspension so they interlock evenly.
Polynesian makers skipped the pulp stage altogether. They soaked and beat the bast on a wooden anvil with a mallet, felting the fibres into large sheets of bark cloth, and they took the tree with them as they settled the Pacific, which is how it reached Hawaii and New Zealand long before any European ship. Modern craft producers still work the same way, and the quality of the sheet depends on how carefully the outer bark was removed.
Paper mulberry suckers from shallow roots and regrows from cut stumps and root fragments, so a tree that is felled often returns as a denser clump. Fruit is carried off by animals, seed moves in water, and the plant grows quickly on bare ground. It is listed as invasive across parts of the eastern United States and in several other regions, and it will colonise railway embankments, quarry spoil and neglected corners with equal enthusiasm.
Growing from Seed
Soak the ripe orange syncarps, rub them through your fingers and rinse away the pulp to free the small achenes. Sow them fresh on the surface of a loam and grit mix, press them in lightly and keep the pan moist and warm in bright light. Seedlings grow quickly, so prick them out as soon as the first true leaves have separated and pot them on before the roots knit together. You can also raise plants from root cuttings and from lengths of hard stem, which is what a coppice block relies on.
In a garden, treat the species as a colony rather than a tree. Plant it where regular mowing will cut back the suckers, or grow it in a large container for the foliage alone. For fibre, cut the canes to the ground each winter and let the stool send up fresh ones. If you do not want the fruit carried away by birds, remove the green heads before they colour, and never leave severed roots lying in damp soil.
Our Take
Grow paper mulberry for the fibre, the felted leaves and the sheer speed of it, and then keep an eye on the boundary, because it does not respect one. If you want the same paper-making quality without the running habit, the closely related kazinoki paper bush is a smaller plant used in the same craft tradition. Compare the foliage with white mulberry, whose leaves lack the lobes and the felted underside, and with paperbush, another Asian fibre plant grown for what its bark can do.
Related Reading
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