Gibbum, scientifically known as the Beechnut gibbum and commonly called the ‘Silver Lady’, is a miniature tree fern. Tropical in appearance and nature, the Blechnum variety of Gibbum prefers rainwater because it is has an intolerance of lime.
More mature plants grow a stout and slender trunk, which can grow to up to three feet, while its fronds can reach lengths of up to two feet. The fronds have dark-silver edges and grow from the top of the trunk, making the plant look like a small palm tree.
Gibbum is native to the islands in the South Pacific, including New Caledonia, Fiji and Hawaii. Its root systems are often used to produce a substrate for growing orchids.
In warmer climates, Blechnum gibbum can be grown outside in a shady, high-humidity spot in good open acid soil that drains well. However, here in the UK, it is important to obtain a cold-hardy plant, or take to growing ornamentally indoors where it can stand drier air better than many other types of ferns.
Blechnum gibbum has been reported to survive temperatures down to -3.8°C, and can re-grow if frozen. This miniature tree fern is propagated by spores, or by division of the clumps, in the spring or autumn, which can take between one and three months to germinate. Very young plants should be transplanted into pots as soon as they begin to produce fronds and kept inside during the winter and then planted in the garden by early summer, if climate allows.
Blechnum gibbum is a genus of the species Blechnum that belongs to the Blechnaceae hard fern family. Most of these are ground dwelling although some are climbers.
Gibbum is a tropical plant and cannot tolerate any frost. It likes a rich potting soil that drains well but retains water. Add some perlite into the potting compost. Gibbum does not like drying out, but take care not to over-water as the fronds will turn brown. Increase the humidity by placing the plant pot on a saucer of pebbles that is half filled with water. It needs a warm climate to thrive outside and grows best in a shady spot with well-drained, acidic soil. Gibbum is prone to pests such as aphids, which can be controlled by wiping the fronds with a damp cloth.
Did You Know?
Ancient tree ferns during the Carboniferous era, about 360 million years ago, were the dominant vegetation on Earth and are the origin of many coal deposits. Today, these kinds of tree ferns are restricted in their natural habitat in tropical regions.