Tree Fern

Cyathia
A genus of nearly 600 species of tree ferns native to mostly moist tropical regions around the world. Most species prefer fertile, sandy, moist, well drained soil in full shade.

* photos of unknown internet source

Cyathea australis ( Rough Tree Fern )
A tree fern native to eastern Australia and Tasmania.
Some records include: largest on record - 50 x 20 feet with a trunk diameter of 3.5 feet; fastest growing - 6 feet per year.
The massive fronds can be up to 30 feet in length with pinnae up to 40 inches in length. The lance-shaped leaflets are up to 4 inches in length.
Hardy zones 8 to 11 ( tolerating 10 F ). It is easy to grow on humus-rich, fertile, moist soil.

Cyathea brownii ( Norfolk Island Tree Fern )
A fast growing, large tree fern that is native to Norfolk Island where it is a dominant part of the landscape. Some records include: largest on record - 100 x 20 feet with a trunk diameter of 3 feet.
The fronds are up to 20 x 5 feet in size. The luxuriant foliage is mid-green.
Tbe trunk is dark to almost black.
Hardy zones 10 to 11 ( hardy to 23 F but the fronds are damaged at 27 F ).

Cyathea cooperi ( Scaly Tree Fern )
A tree fern native to eastern Australia and Tasmania.
Some records include: largest on record - 50 x 25 feet with a trunk diameter of 8 inches; 13 years - 20 feet; fastest growing - 3 feet per year. It can reach a canopy width of 6 feet in 1 year.
The massive fronds can be up to 30 feet in length with pinnae up to 40 inches in length. The lance-shaped leaflets are up to 4 inches in length.
Hardy zones 9 to 11 ( tolerating 20 F ). It is easy to grow on humus-rich, fertile, moist soil. Easy to grow and is more drought tolerant than most Cyathea species.

* photos taken on Aug 23 2014 @ U.S. Botanical Garden, Wash., DC

Cyathea cunninghamii
Some records include: largest on record - 45 x 13 feet with a trunk diameter of 0.8 feet.

Cyathea dealbata ( Silver Tree Fern )
A slow growing, large tree fern that is native to New Zealand. Some records include: largest on record - 40 x 20 feet with a trunk diameter of 1.5 feet. One had reached a size of 23 feet with a trunk diameter of 1.5 feet in Ireland.
The fronds are up to 15 x 4 feet in size, with pinnae up to 20 inches in lenght that are composed of leaflets up to 4 inches in length. The foliage is mid-green above, silvery-white beneath. It requires a protected size as high winds can damage the fronds.
Hardy zones 9 to 11 ( tolerating 14 F ).

Cyathea dregei ( Cape Tree Fern )
A tree fern, native to South Africa, that can reach a maximum size of 30 x 10 feet with a trunk diameter of 2 feet.
The fronds, up to 10 feet long, are divided up into oblong leaflets, up to 3 inches in length. The fronds arch down then turn upwards towards the tips. The foliage is deep green above, bright green beneath.
Hardy zones 8 to 10 ( tolerating as low as 7 F ). It has good drought tolerance unlike most Cyathea species.

Cyathea medullaris ( Black Tree Fern )
A fast growing, large tree fern, reaching up to 50 feet, that is native to New Zealand, Australia and nearby Pacific Islands. Some records incude: 82 x 40 feet with a trunk diameter of 2.5 feet. Some had reached 17 feet with a trunk diameter of 1 foot in Ireland.
The very attractive fronds are up to 22 x 6.5 feet in size.
Hardy zones 8 to 11

Cyathea mexicana
A tree fern, reaching up to 33 feet with fronds up to 10 feet in length.

Cyathea princeps
Reaches up to 65 feet with fronds up to 15 feet in length. It is moderate growing, up to 2 feet per year.

Dicksonia

Dicksonia antarctica
Some records include: largest on record - 50 feet with a trunk diameter of 3.8 feet. It is native to moist, mountain forests from Queensland to Tasmania in eastern Australia. It is often found under dense eucalyptus canopy in the wild. It is long-lived, up to 400 years.
The fronds, up to 14 x 6 feet in size, are divided up into leaflets up to 2 x 0.4 inches in size. The attractive foliage is deep green.
The fibrous, upright trunk is deep brownish-black.
Hardy zones 8 to 10, it becomes deciduous at 19 F.

* historic archive photos

Dicksonia australis
Some records include: largest on record - 36 x 19 feet with a trunk diameter of 4.7 feet.

Dicksonia fibrosa
A slow growing, tree-fern that is native to New Zealand. It can reach a maximum size of 25 x 10 feet with a trunk diameter of 2 feet. One in Cork, Ireland, reached as large as 13 feet with a trunk diameter of 1.3 feet.
The fronds are up to 8 x 2.5 feet in size. The foliage is deep green.
The fibrous, upright trunk is reddish-brown.
Hardy zones 8 to 10, preferring a cool, shaded, moist environment. It has survived on a protected site in Seattle, Washington.

Dicksonia sellowiana
A tree fern that is native to tropical regions from Mexico to Brazil. It can reach a meximum height of 33 feet with a trunk diameter of 1 foot.
The 2 to 3 pinnate fronds are up to 10 feet in length. The pinnae are up to 16 inches in length.
The fibrous trunk is upright.
Hardy zones 8 to 10

Dicksonia squarrosa ( Hard Tree Fern )
A moderate growing, tree fern from New Zealand that can reach a maximum size of 40 x 15 feet with a trunk diameter of 1 foot.
The 2 to 3 pinnate fronds are up to 10 feet in length with pinnae up to 20 inches long. The foliage is deep green above, pale green beneath. The leaf stalks are densely deep brownish-black hairy.
Hardy zones 8 to 10.

* historic archive photo