Fern trees, also called tree ferns, are actually ferns that have treelike trunks. The base of the plant is considered a fake trunk, as it resembles a tree trunk. It's actually a mantle of thick aerial roots. These plants originated from prehistoric vegetation. The pulu is the tree's brown fuzzy part found on the bottom of its branches and over frond buds. Interestingly, pulu was used in stuffing the bodies of dead Hawaiians when their organs were removed, notes the Hawaii Public Schools website.
Tree ferns have a form that resembles a palm tree. They have a soft texture, lacy leaves and many branches. Typically, these plants have single stems and are crowned by a large rosette of leaves, according to the New Zealand government website. While individually their roots are weak, the root mantle has considerable strength when all the roots are grown together, forming the plant's trunklike structure, according to the Illinois State Geological Survey.
Tree ferns help give a tropical look to a landscape. The tips of new leaves and the core can be cooked and used as food for both pigs and people, according to Hawaii Public Schools. Besides stuffing dead bodies, the plant's pulu has been used for stuffing pillows and mattresses. Today the trunks of dried tree ferns are carved into flower pots. They're also cut into blocks so they can be sold as fern logs.
There are more than 800 tree fern species, according to the University of Hawaii at Manoa. Tree ferns are found scattered over much of the world, according to the Tropical Centre website. They originated in New Zealand and Tasmania in cool, high elevations. Although they do better in shade, with adequate water they can grow in sunny areas.
The mamaku (Cyathea medullaris) is considered the most majestic of the tree fern species, according to the New Zealand government website. This species grows more than 40 feet high by 1 foot wide. Individual fronds grow up to 15 feet long by 6 feet wide. The plant's main frond stems are black and stout.
Ponga (C. dealbata) is a species that has a distinctive white color under its leaf surfaces. This species grows up to 30 feet tall with fronds up to 10 feet long. It has pale, brownish-green fronds.
Wheki (Dicksonia squarrosa) is probably the most common tree fern, as well as the most persistent after a forest is removed. It often forms groves for spreading underground rhizomes.
All tree ferns are considered threatened species. This is because there are a vast amount of them that are only found in rain forests around the world that are quickly diminishing. It's against the law to ship either tree ferns or tree fern products internationally, warns the University of Hawaii at Manoa.