Dicksoniaceae

Tree ferns ( Dicksonia antarctica) in Nunniong, Australia

Dicksoniaceae are a family of tree ferns ( Cyatheales ). All representatives also have a tree -like growth habit.

History

The tree ferns colonize the earth since the Devonian, so since about 400 million years ago. At that time also Bärlapppflanzen ( Lycopodiophyta ) and horsetails emerged ( Sphenophyta ). In the Carboniferous, they are among the dominant plant species and strain reached heights of up to 30 meters well. Due to their high geological age of these plants are counted among the living fossils. With the advent of seed plants the tree ferns were displaced. Tree ferns were tropical plants in other geological eras, there are also in the geological strata in Central Europe fossils of tree ferns, but in those times there was in Europe a tropical climate.

Occurrence

Tree ferns grow in tropical and subtropical areas of the world. Some species tolerate the moderate climate of rainforests in Australia, Tasmania and New Zealand and adjacent regions (Malaysia, Lord Howe Island ). In general, tree ferns tolerate no ongoing drought, and only a few species (eg Dicksonia antarctica) survive mild frosts.

In studies in hitherto uninvestigated areas of New Guinea New species are regularly discovered. At the same time, some species are due to the collection for the ornamental trade, intensive logging and habitat loss greatly threatened or extinct.

Description

The fronds of tree ferns are in full-grown specimens often about 1 meter long, and almost always feathered one or more times. However, a simple way has ungefiederte fronds.

Reproduction takes place as with all ferns by spores which are formed at the tree ferns at the frond base in sporangia.

Unlike seed plants, tree ferns show no growth in thickness of the trunk. The log is supported by the root bundles that form during growth.

Plants with a similar appearance, the cycads and palms. None of these groups of seed plants (also not with other ferns ) related to the tree ferns.

Economic Importance

Tree ferns have been imported since the 19th century as ornamental plants to England and there about popular plants in the tropics worldwide. and in many other areas of the world with only low frosts, for example the south of England with his ( influenced by the Gulf Stream ) maritime climates, planting in landscape parks and gardens.

Ornamental plants of commercial significance are found in the Dicksoniaceae in the genus Dicksonia. In very bright, cool room in winter, or in conservatories some Dicksonia species can be maintained.

System

The Dicksoniaceae family consists of three genera:

• Calochlaena Maxon, with about five species.
• Dicksonia L' Hér. , With at least seven species.
• Lophosoria C. Presl, with only one type of tropical America: Lophosoria quadripinnata ( J. F. Gmel. ) C. Chr

Other genera previously asked in this family now belong to other families within the tree ferns.