Tree fern

Source: Wikipedia, the free encyclopedia.
A tree fern near Belles, Dominica
Alsophila sp. tree ferns overlooking a valley in Misamis Oriental, Philippines

The tree ferns are arborescent (tree-like)

Osmundales where the extinct Guaireaceae and some members of Osmundaceae also grew into trees. In addition there were the Psaroniaceae and Tietea in the Marattiales
, which is the sister group to most living ferns including Cyatheales.

Other ferns which are also tree ferns, are

Cystodium and Sadleria from the order Polypodiales, and smaller members of Cyatheales like Calochlaena, Cnemedaria, Culcita (mountains only tree fern), Lophosoria and Thyrsopteris
are also considered tree ferns.

Range

Tree ferns are found growing in tropical and subtropical areas worldwide, as well as cool to temperate rainforests in Australia, New Zealand and neighbouring regions (e.g. Lord Howe Island, etc.). Like all ferns, tree ferns reproduce by means of spores formed on the undersides of the fronds.

Description

Reconstruction of Tempskya, an extinct fern from the Cretaceous

The fronds of tree ferns are usually very large and multiple-

pinnate. Their trunk is actually a vertical and modified rhizome,[4] and woody tissue is absent. To add strength, there are deposits of lignin in the cell walls and the lower part of the stem is reinforced with thick, interlocking mats of tiny roots.[5] If the crown
of Dicksonia antarctica (the most common species in gardens) is damaged, it will inevitably die because that is where all the new growth occurs. But other clump-forming tree fern species, such as D. squarrosa and D. youngiae, can regenerate from basal offsets or from "pups" emerging along the surviving trunk length. Tree ferns often fall over in the wild, yet manage to re-root from this new prostrate position and begin new vertical growth.

Uses

Tree-ferns have been cultivated for their beauty alone; a few, however, were of some economic application, chiefly as sources of starch. These include the Sphaeropteris excelsa of Norfolk Island that was threatened with extinction for the sake of its sago-like pith, which was eaten by pigs. It is now widely cultivated as an ornamental tree, although there is only one small wild population on Norfolk Island.[6] Sphaeropteris medullaris (mamaku, black tree fern) also furnished a kind of sago to people living in New Zealand, Queensland and the Pacific islands. A Javanese species of Dicksonia (D. chrysotricha) furnishes silky hairs, which were once imported as a styptic, and the long silky or wooly hairs, abundant on the stem and frond-leaves in the various species of Cibotium have not only been put to a similar use, but in the Hawaiian Islands furnished wool for stuffing mattresses and cushions, which was formerly an article of export.[7]

Species

Transplanted Dicksonia antarctica tree ferns at Combe Martin Wildlife and Dinosaur Park, North Devon, England

It is not certain the exact number of species of tree ferns there are, but it may be close to 600-700 species.

extinct in the last century as forest habitats have come under pressure from human intervention.[citation needed
]

References

  1. ^ Historical reconstruction of climatic and elevation preferences and the evolution of cloud forest-adapted tree ferns in Mesoamerica - NCBI
  2. ^ Chronogram of the Cyatheaceae and other tree fern lineages
  3. hdl:11336/49538
    .
  4. ^ Trends and concepts in fern classification - NCBI
  5. ^ Stem - The University of Auckland
  6. ^ "Norfolk Island Plants". Norfolk Island National Park. Australian Government Parks Australia. Retrieved 6 April 2023.
  7. ^  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Tree-Fern". Encyclopædia Britannica. Vol. 27 (11th ed.). Cambridge University Press. p. 235.
  8. OCLC 785808931
    .

External links
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