What is Dicksonia?

Dicksonia is a genus of tree ferns with about 25 species native to parts of Central America and Oceania, as well as the island of St. Helena in the South Atlantic Ocean. It is a very old genus, believed to date back at least to the Certaceous period of 65 million years ago. The genus exhibits its greatest diversity on the island of New Guinea, which has five Dicksonia species.

Commonly called the soft tree fern or Tasmanian tree fern, Dicksonia antarctica is native to parts of Australia and is the most easily cultivated Dicksonia species. It can be reproduced from spores or cuttings, and is grown ornamentally as a house or garden plant, or for use in landscaping. D. antarctica can grow as tall as 50 feet (15 meters), but is usually only about a third that size.

The soft tree fern grows best in organic soil, in areas with abundant rainfall and mild temperatures. It is tolerant of fire. The starchy pith on the inside of the trunk can be eaten, either raw or cooked.

The New Zealand tree fern, or Dicksonia squarrosa, is, as the name suggests, native to New Zealand, though it is also cultivated as a garden plant beyond its native range. The New Zealand tree fern can reach 20 feet (6 meters) in height. It is a hardy and fast growing plant. It tolerates wind and sun fairly well, but will do best with some protection against the elements. The fronds are dry to the touch and grow at the top of the plant, giving the New Zealand tree fern a palm tree like appearance.

The bristly tree fern, Dicksonia youngiae, is native to rain forests of Australia. It is one of the least hardy members of the genus, vulnerable to both heat and wind. The bristly tree fern grows to be 14 feet (4 meters) in height, and features multiple trunks. Its fronds are a rich green, and its fiddleheads, the uncurled fronds, are covered in coarse red hairs.

Dicksonia arborescens, or the St. Helena tree fern, grows only on the island of St. Helena and is of vulnerable conservation status. It is also important to many other threatened endemic species, which rely on the tree fern for shelter and a place for seedlings to grow. The young plants germinate or sprout on the trunk of the St. Helena tree fern.

Dicksonia is a genus of tree ferns known for their large fronds and substantial, often woolly trunks. They are primarily found in the moist, shaded forests of the Southern Hemisphere, including parts of Australia, New Zealand, South America, and the islands of the Pacific. These ancient plants are remnants of prehistoric times and thrive in environments with high humidity and stable temperatures.

Dicksonia ferns are renowned for their longevity. Some species, like Dicksonia antarctica, can live for several hundred years. Their slow growth rate contributes to their long lifespan, with some individuals only growing about 2.5 cm in diameter each year. This makes them living fossils, providing a glimpse into the flora of ancient times.

Dicksonia ferns flourish in moist, well-drained soil with plenty of organic matter. They prefer shaded or semi-shaded areas that mimic their natural understory habitat. Consistent moisture is crucial, but they do not tolerate waterlogged conditions. A stable climate with mild temperatures and high humidity mirrors their native environment, promoting healthy growth.

Yes, Dicksonia ferns can be cultivated in gardens, provided the conditions are right. They are popular in temperate and subtropical regions for their dramatic foliage and as a feature in shaded garden areas. Gardeners should ensure adequate moisture, shade, and protection from strong winds. In colder climates, they may require winter protection or cultivation in a greenhouse.

Some species of Dicksonia are considered at risk due to habitat loss and over-collection. For example, Dicksonia sellowiana is listed as vulnerable by the IUCN Red List of Threatened Species, primarily due to deforestation and the fern trade. Conservation efforts are in place to protect these species in their natural habitats and regulate trade.

Dicksonia ferns reproduce through spores, which are produced in sporangia located on the underside of their fronds. When conditions are favorable, the spores germinate to form a small, heart-shaped gametophyte, which then produces the sex cells. Fertilization results in a new sporophyte, which will grow into the familiar tree fern. This cycle can take several years to complete.