Cyathea is a genus of about 470 species of tree fern growing throughout the world's tropical climates. Most species have a single tall stem and a fibrous mass of roots. Some species have creeping or branching trunks, but they are rare.
The Norfolk tree fern, Cyathea brownii, is the world's largest species of tree fern, able to reach at least 67 feet (20 meters) in height. In the wild, C. brownii grows only on Norfolk Island. It is sometimes cultivated, and is easy to grow from spores, but its height and susceptibility to frost present difficulties to the gardener. The plant requires well-drained soil, high humidity and frequent watering, and good light.
C. cooperi, native to Australia, is one of the most commonly cultivated tree ferns. Its common names include Cooper's tree fern, Australian tree fern, and lacy tree fern. It is valued for its hardiness, as it is easy to grow in many different climates. Cooper's tree fern grows best in a shady, protected environment with moist soil. It has been naturalized outside its native habitat, and has become an invasive species in Hawaii.
The silver tree fern, C. dealbata, has a native range limited to New Zealand. Its common name refers to its silver fronds. C. dealbata can grow to 33 feet (10 meters) in height, and rare, creeping varieties of the fern exist. The tree is often used as a symbol of New Zealand, particularly by New Zealand sports teams. This tree fern grows best in well-drained soil, and requires protection from high winds and frost.
C. medullaris, the black tree fern, is also only found in New Zealand. It is much taller than the silver tree fern, approaching the height of Norfolk tree ferns. This tree fern is named for its black trunk. Its timber has been used as a rough building material.
Other species of Cyathea native to the Pacific include C. propinqua, which grows in Fiji and Samoa, and C. semiamplectens, native to New Guinea. Asian Cyathea species include C. squamulata, native to Southeast Asia, and C. chinensis, native to parts of China, India, and Southeast Asia. C. acanthophora grows only on the island of Borneo. Some Cyathea plants in the western hemisphere include C. abbottii, native to Hispaniola, and C. delgadii, which grows throughout Central and South America and the Caribbean.