Dicksonia is a genus of tree ferns in the family Dicksoniaceae, placed within the order Cyatheales. The genus is regarded as closely related to Cyathea, though it is considered to retain more primitive morphological traits. Its fossil record extends at least to the Jurassic and Cretaceous periods, evidenced by preserved stems, pinnules, and spores, making Dicksonia one of the more ancient lineages among living ferns.
The genus comprises approximately 20 to 25 species. These are large, trunk-forming ferns whose "trunks" are not true woody stems but densely matted masses of roots and fibrous tissue, sometimes reaching several metres in height. Fronds are large, arching, and finely divided.
Dicksonia has a remarkably wide but disjunct distribution, occurring from Mexico south through Central America to Argentina, Brazil, Uruguay, and Chile; on the Atlantic island of St. Helena; across New Zealand, New Caledonia, and Australia; and through Indonesia, New Guinea, and the Philippines. New Guinea is the centre of diversity, hosting five species.
Several species are cultivated as ornamental garden plants in temperate and subtropical climates, notably Dicksonia antarctica (soft tree fern), Dicksonia fibrosa (woolly tree fern), and Dicksonia squarrosa (rough tree fern). The genus was formally described by Charles Louis L'Héritier de Brutelle in 1788, who named it in honour of James Dickson, a prominent British nurseryman and botanist.
Etymology
The genus Dicksonia was described by Charles Louis L'Héritier de Brutelle in 1788. The name honours James Dickson (1738–1822), a prominent British nurseryman, cryptogamist, and botanist known for his work on mosses and fungi.
Distribution
Dicksonia has a wide, disjunct distribution spanning the Americas (Mexico to Chile and Argentina, including Brazil and Uruguay), the Atlantic island of St. Helena, and the Asia-Pacific region (Australia, New Zealand, New Caledonia, Indonesia, New Guinea, and the Philippines). New Guinea supports the greatest species diversity within the genus.
Cultivation
The most widely cultivated species is Dicksonia antarctica, the soft tree fern, valued for its hardiness and tolerance of cool, moist conditions in temperate gardens. Dicksonia fibrosa (woolly tree fern) and Dicksonia squarrosa (rough tree fern), both native to New Zealand, are also grown ornamentally. Tree ferns in this genus are typically propagated by spores or by transplanting established trunks.
