Treefern: Cyathea

• Cyathea
  This is by far the largest genus of tree ferns, containing over 800 species. Many are strictly tropical, but some come from temperate areas cool enough that they can be grown in more extreme climates. Even some of the tropical ones seem remarkably adaptable to temperate climates with light frosts, and cold-hardiness limits have not yet been found for some of these. Compared to Dicksonia, the most common Cyathea species generally grow faster when young, and, in my opinion at least, they are a bit more on the primitive-looking side and not quite so woodland-ish (although the Dicksonias are actually more primitive). Considering the sheer number of species in existence, it is possible that the following small handful listed are only a fraction of those that could be grown in cool climates. Those belonging to the Sphaeropteris group can be distinguished by their thick, fleshy stipes; in contrast to the smaller, woody stipes of the Alsophila group.
  

Cyathea australis -"Rough Tree Fern" From the forests of Southeast Australia comes this medium to large sized tree fern. In the wild it inhabits moist mountain areas in Victoria, New South Wales, and Queensland, and is often found growing in the company of Dicksonia antarctica but preferring more sunny open spots. Although well-known to Australians, it is not common in cultivation outside of Australia. Most plants labeled as Cyathea australis in cultivation are unfortunately C. cooperi, and a great deal of confusion has existed between the two in the United States, though there is no good reason why the two should be confused since they are quite distinct from one another. C. australis is by far the cold-hardiest of the two. For a description of the differences, see Cyathea cooperi. C. australis is a rather close relative of C. woolsiana.
Cyathea australis is an attractive, reasonably fast-growing treefern with a stocky, black trunk and fronds that range in length from 6 - 10'. However, occasionally individuals are found with a very immense trunk and fronds as long as 20'! It grows at elevations as high as 4,200' in Southeast Australia, and most of my sources are of the opinion that it is slightly more cold-hardy than Dicksonia antarctica. Its most cold-hardy provenances probably have their limits around 10°F, but certainly not without substantial frond damage. Indeed, the fronds are often lost by the end of a winter in Australia, as is the case with Cyathea dregei in South Africa. However, the tender uncurling croziers are certainly more tolerant of frost than those of Dicksonia; and since it inhabits more open situations, it is more exposed to frosts in the winter. It ought to be hardy enough to make a reasonably easy subject in the Pacific Northwest and Britain, probably with a bit of protection in cold winters to be safe; where it would need a position with some sun to thrive since it is not as shade tolerant as Dicksonia antarctica. It also tolerates heat fairly well and would be likely to succeed in the Southeast United States with enough water.
This species can sometimes (especially in Australia) be found for sale with all the fronds and roots cut off. Although a Dicksonia may survive this treatment, Cyatheas most often do not unless they have been cut off below ground level.
Cyathea australis ssp. norfolkensis from Norfolk Island is an extremely large, robust form of this species. It is rare in cultivation and its cold hardiness is not known.

Cyathea brownii -"Norfolk Island Tree Fern" This is regarded as the largest of all treeferns, though in cultivation its dimensions may be exceeded by other species such as C. medullaris, particularly in a cooler climate. A very robust, beautiful species, closely related to C. cooperi but far more spectacular in size and appearnace. It is not very common in cultivation outside of Australia. The fronds can reach up to 20' long and are held in a most attactive habit, and the trunk, which is quite thick under humid conditions, can in the wild reach an incredible height of 100'! As the fern ages, the trunk appears to look more woody and may also show some taper.
Although it comes from a completely frost free environment, it will tolerate nearly as much frost as C. cooperi, and is also very fast-growing (especially as a young plant) and easy to cultivate, responding to large quantities of fertilizer. The uncurling croziers are covered in beautiful large, pale brown scales and small, dark brown scales. The fronds are hardy to about 27°F, and it is well worth overwintering in a zone 8b climate with copious amounts of house insulation, although it will eventually outgrow practical protection measures. It will perform well in partial sun in most climates where it is hardy (full sun advised in cool maritime climates), and its fast growth enables it to recover from damage quickly. Very easily raised from spore.

Cyathea capensis- This tree fern from the Cape region of South Africa finally seems to be getting a bit more attention from tree fern enthusiasts. Its fronds are a deep green and rather glossy, attatched to long stipes, and the slender trunk can reach about 20' tall in the wild. According to one reference, it is said to develop a bit of a "wig" around the crown in the manner of C. baileyana. Unlike the other South African tree fern, C. dregei, it prefers to inhabit very sheltered, cool, shady streambanks several thousand feet above sea level.
This species is easy to grow in a semi-shady, moist, sheltered situation; and I think we can be fairly certain it ought to tolerate several degrees of frost, though its cold-hardiness limits are not known. A similar but distinct species occurrs in southern Brazil that should also be tried for hardiness. C. capensis has also been reported in other parts of East Africa.

Cyathea colensoi-This small Cyathea from New Zealand is regarded as New Zealand's most cold-hardy tree fern. It grows at rather high elevations and shows a definite preference for cool climatic conditions. It usually has the habit of creeping along at ground level rather than forming an upright trunk, and therefore may not qualify as a "true" tree fern in the opinion of some. The fronds are small, broad and shiny.
I am not aware that it is in cultivation outside of New Zealand, but it should certainly be introduced. Perhaps it could be coaxed into growing an upright trunk in an ideal garden situation with copious amounts of fertilizer and water. Even in the wild, some individuals have been known to grow some upright trunk. They are accustomed to partial shade and a moist soil.

Cyathea cooperi -"Australian Treefern" "Lacy Treefern"
This is probably the second most common treefern in cultivation after Dicksonia antarctica. It is well-known over much of the world and not difficult to find in areas where it is well adapted. Its popularity is probably a result of its great ease of growth and tolerance of neglect. It hails from eastern Australia, but does not grow at nearly such high elevations as Cyathea australis and Dicksonia antarctica do. The first common name is the one Americans have given it, without regard to the fact that there is a great number of treefern species from Australia. "Lacy treefern" is the Australian name, which refers to the texture of the fronds compared to Cyathea australis ("Rough treefern"). Not surprisingly, some variation occurs within this species, and as a result several named forms such as 'Brentwood', 'Emerald Beauty' and 'Kalgoorie Gold' are in cultivation.
In cultivation this species is often confused with Cyathea australis. If in doubt, it's probably C. cooperi, because there are far fewer C. australis in cultivation. The two are easily distinguished: C. cooperi, in most cases, has white and brown scales on the stipes (see photo), while C. australis has only the brown ones (see photo). C. australis also has spines at the bases of the stipes, and C. cooperi has a much more fleshy stipe than C. australis. There are also differences in their reproductive structures. The most important difference to many fern entusiasts is that C. australis is far more cold-hardy.
Cyathea cooperi has a slender trunk usually about 3 - 6" thick, sometimes growing to 30' high, and puts on growth very quickly. The fronds typically will reach about 8' long on a mature specimen, but, as with most tree ferns, they will be significantly stunted if kept in a pot. It will grow well in dappled (but not deep) shade, but also does well in some sun, even in hot climates, as long as the moisture supply is adequate. It also does relatively well in exposed, windy situations. These features make it a splendid treefern for a wide variety of sites.
Although Cyathea cooperi has been overwintered successfully in England and other cool climates, I do not generally tend to recommend it to gardeners in such locations unless they really want it for their collection, or it is the only species they can get hold of. It is not particularly cold-hardy; and the fronds will usually burn at about 27°F or so. Complete mortality generally occurs below 22°F, though some have recovered. It is, in fact, the least hardy species of Cyathea to which I have given a sub-page of its own (and I've done this only because it is such a well-known species). My reasoning is that if you are willing to go to the trouble of overwintering such a cold-tender treefern in a zone 8 or 9a climate, some equally hardy yet far more spectacular species such as C. brownii, C. howeana, and C. robusta are more worth your effort. C. cooperi grows very easily from spore.

Cyathea cunninghamii -"Slender Treefern" Coming from New Zealand, Tasmania, and eastern Australia, this tall tree fern has probably not been introduced to cultivation in the United States or Britain just yet. In the wilds it always inhabits cool, humid, shady gullies and streambanks, and as a result it is very fussy about its requirements for coolness, moisture, shade and shelter from wind. It is a close relative of C. medullaris, but it is likely to be considerably hardier to cold, since it grows higher up in the mountains where snow often falls. Its crown is much more thin and open, containing fewer fronds than most of the other tree ferns discussed here. It is one of the tallest hardy tree ferns, often found towering over Dicksonia antarctica and Dicksonia fibrosa in habitat.
Because of its insistence on cool, sheltered conditions, it would probably be best suited to the maritime climates of Britain and parts of the Pacific Northwest in the Northern Hemisphere. In the Melbourne area of Australia it is quite a challenge to keep alive through the hot summers. But it should certainly be tried in cooler areas--its slender habit, soft-textured fronds and open crown could make it a very attractive subject in a cool woodland setting.

Cyathea dealbata -"Ponga" "Silver Tree Fern" This magnificent tree fern comes from the dense, lush forests of New Zealand. Its most prominent distinguishing characteristic is that the fronds are a beautiful silver-white underneath, and the stipes are silvery as well. Other than that it is reasonably similar to C. australis, though it prefers more shade and shelter. The silvery fronds make it an exceptionally superb subject for night lighting. It is extremely rare in cultivation outside of Australia and New Zealand.
The arching fronds are very large, sometimes up to 12', and form a beautiful, full, dense crown. Trunk development begins rather slowly compared to some other species, and the fronds on young plants may not be silvery.
Although it shows a definite preference for moisture and cool conditions, it does seem somewhat adaptable and relatively easy to grow even in relatively dry conditions (as ferns go). Some plants can be a bit cold-hardier than commonly thought, as it does range well into the mountains of New Zealand's South Island, and good provenances may be able to withstand temperatures around 22°F (perhaps lower) without any trouble. One specimen grew well for many years at Logan Botanical Garden at Stranraer, Scotland, and even recovered from a temperature of 14°F on one occasion. It should be able to grow well in the Pacific Northwest and Britain with the standard protection measures. As far as I am aware its heat tolerance remains untested, but it is worth trying in hot climates.

Cyathea dregei- Cyathea dregei is a rather large, stout-trunked tree fern from the forests and grasslands South Africa, Madagascar and other parts of east Africa. It seems to have made it into culativation just recently in Europe, but is largely unknown in the United States. It is of great interest for several reasons.
It grows over a large area in which the climate ranges from temparate to tropical, and areas with dry winters and wet summers as well as areas that are the other way around (the western Cape). Some of this region is surprisingly arid and hot, yet this treefern is usually found growing out in the open in full sun (somewhat like C. australis), though always near streambanks or in sites where it can get a constant supply of soil moisture. In addition to summer heat, it must also tolerate severe winter frosts and snow. Because of the open situations which it chooses to inhabit, it is subjected to the full effect of the frost without the benefit of an overhead canopy. It is also described as "deciduous," and though this is probably not technically correct, it seems that this treefern does not mind losing its fronds and growing them back as much as other treeferns do. The fronds can be damaged from temperatures as high as 30°F, and most winters in South Africa they are, but with no lasting ill effect to the plant.
Because of its large natural range, its hardiness is likely to vary somewhat according to where the spore was collected. One nursery in Germany has rated it to 7°F, and although I am not quite that optomistic, one has been thriving in Edinburgh, Scotland for several years now. I think it may be an excellent prospect for Britain and the Pacific Northwest, as well as relatively arid or hot temparate climates such as the southern United States.
All of these characteristics imply a general toughness and adaptability that other treeferns lack. On the negative side, it is very slow-growing and takes many years before the trunk starts developing. But mature specimens are magnificent and well worth the wait: the fronds may reach 8' or more, making up a very attractively spreading crown; and the trunk is usually 18 - 22" thick.

Cyathea latebrosa-This moderate sized, attractive tree fern from moderate elevations in the Himalayas remains very rare in cultivation. It ought to tolerate a few degrees of frost but its exact hardiness is not known. It prefers open sites with at least some exposure to sun, and appreciates warm, humid summers.

Cyathea leichhardtiana-This species from southeast Australia is one of the least common Australian species in cultivation. Although perhaps slightly hardier than C. celebica (guessing around 22°F), to which it is closely related, it is usually considered inferior in appearance unless given plenty of shade, shelter and moisture which it requires. In such a position however it is very rewarding to grow since the fronds are very attractive as they expand: the stipes and pinnae expand first while each individual division on the pinnae remains curled up in a little ball for a while before finally expanding. Cyathea leichhardtiana is tall and slender in stature and grows rather slowly, ultimately achieving a height of about 20' with fronds typically about 9' in length. Like C. celebica the stipes are covered with black spines. English growers report some difficulty in raising this species from spore.

Cyathea X marcescens -"Skirted Tree Fern" An extremely rare treefern found only in a few sheltered gullies in Tasmania, Victoria, and New South Wales. It is now generally believed that they are of hybrid origin, probably resulting from a cross between Cyathea australis and Cyathea cunninghamii. It is very fast-growing, large, and very distinctive; a fern of deep ravines and streambanks. The trunk may grow to a height of 30' tall and over 16" thick, with fronds sometimes exceeding 12' in length. It certainly has the potential for great ornamental worth in cold climates. Unlike C. cunninghamii, the dead fronds tend to persist around the trunk forming a skirt.
Only a small population of about 40 plants occurs in Tasmania, but Victoria has some larger populations. As all attempts to raise this fern from spore have failed, it probably does not produce fertile spore as a hybrid. However it has been theorized that plants can be obtained by sowing a small amount of Cyathea australis spore with a large amount of C. cunninghamii spore, saving a large proportion of the offspring and picking out the hybrids as they develop. So unfortunately it may be a while before temparate gardeners will be able to test these out. It will almost certainly be hardy to 20°F or lower, and could make a spectacular addition to a cool zone 7 or 8 garden with some protection.

Cyathea medullaris -"Mamaku" "Black Tree Fern" This very large treefern is native to New Zealand, Fiji, and Polynesia. In New Zealand it is possibly the most common tree fern, and it is found growing in a large range of microclimates and situations throughout the island. It is a rapid grower and makes a very imposing specimen even in less than perfect conditions. Unlike C. dealbata and C. smithii, it generally found growing in open places with full exposure to wind and sun. Although relatively few fronds remain on the crown at once, they can reach over 12' long on vigorous young plants. Its large size and black shiny leaf bases make it a most spectacular plant in cultivation. This species is not yet common in gardens, though there are a few in the British Isles, including one that has already spent a few winters outdoors in Ireland.
Although it is very adaptable, it seems to be only slightly hardier than C. cooperi, and its massive size makes it a formidable challenge to protect from cold. In addition to this, its preference for open places limits the number of positions in a garden or landscape available to site it that are relatively sheltered from cold. It ought to be able to withstand temperatures down to about 25°F before the cold would begin to do serious damage. Some high elevation provenances may be a couple degrees hardier than this. The ideal situation for it is where its fronds get full sun, but the trunk can remain moist.

Cyathea robusta-Cyathea robusta is a large, very beautiful species from Lord Howe Island. It has very attractive, thick, erect fronds and light brown scales on the croziers, not unlike C. brownii. As the stipes mature the scales fall leaving the thick, light green stipe visible. The fist-sized croziers of this species are spectacular when uncurling in the spring. A good performer in cultivation, it has been known to withstand frost and snow in Victoria (although cold-tender when small), and is probably a tad hardier than C. cooperi (guessing 25°F). It does not resist hot temperatures well when young either.

Cyathea smithii -"Whe" This is a rather large tree fern coming from the cool mountain forests of New Zealand, especially the South Island, as well as the Subantarctic Auckland Islands. It has a very beautiful habit with its broad, soft fronds; and the stipes have dark scales and a yellow midrib. Rather than uncurling in the manner of most tree ferns, in which the main frond stalk unrolls almost to its full length before the "frondlets" (pinnae) unroll; the fronds tend to expand all at once up the length of the frond. The fronds often leave a skirt around the slender, fibrous trunk after they have died, which allows other ferns and epiphytes to grow on the lower parts of the trunk. The stipes hanging over the trunk are very characteristic of this species and make it easy to indentify among other New Zealand species.
This is one of the cold-hardiest of New Zealand's tree ferns. Though it remains largely untested in cultivation, it may be able to withstand temperatures down in the range of 15-20° F. Interestingly, it does not even seem fully hardy in its native region, and in fact during the once-in-a-century freeze of July 1996, about 50-75% of plants growing in the coldest parts of their homeland were killed. Perhaps the hardiest treeferns of this species will come from spore of treeferns that survived this devastating freeze. Also, C. smithii, like C. australis and C. dregei, usually loses its fronds by the end of winter, suggesting that frond protection is not important for this species as long as the crown survives.
Although it is said to be rather fast-growing, I am not optomistic for its widespread cultivation because it does not seem to be tolerant of much heat. It is said to be unsuccessful on the warmer parts of New Zealand's North Island, and it does not seem to be in cultivation much in Australia. However, it is likely to do well in England, where unfortunately most plants sold as C. smithii are not, and it may be satisfactory in the Pacific Northwest, if attention is given to place it in a cool site sheltered from wind. It is much less happy in exposed sunny situations than other New Zealand tree ferns and should be given a forest-like setting. Imported specimens transplant relatively easily for a Cyathea, establishing quickly. It should also be kept continually moist, as it is likely to have a very low tolerance for dryness.

Cyathea spinulosa-This treefern from India, Thailand, China, Taiwan, and Japan remains rare in cultivation outside of Asia. It requires a moist, sheltered position to thrive, but is also able to recover from harsh treatment. In one instance it was allowed to dry out and yet grew back, though slowly. The 10' fronds are dark green and finely divided, held in a graceful arching habit, and the slender trunk is able to reach a height of about 20'. It has a vigorous root system and may not be very well adapted to pot culture, but it does seem to have at least a few degrees of frost tolerance. It adapts best to a summer-moist climate, thriving from Kathmandu to Japan.

Cyathea tomentosissima -"Dwarf Wooly Tree Fern" Cyathea tomentosissima is a rather small tree fern that hails from the cool mountain cloudforests and grasslands of New Guniea at very high elevations. This is a climate lacking in seasonal extremes, except for the intensity of the sunlight, nothing like any of the climates in the temparate Northern Hemisphere. This treefern seems to have found its way into cultivation in Europe, Australia, and even the United States, though it is still overall very rare.
It does not grow as fast as most of the other tree ferns, and its ultimate size is only about 8' tall with fronds up to 4' long under good conditions. Its small size makes it easy to incorporate into a city garden, and it will also grow well in pots or tubs. Also, it is not much of a chore to wrap up such a little fern to protect it from the winter cold.
Despite its origin in a perpetually cool climate, it seems to be strangely and remarkably adaptable, in fact one of the most cool- and heat-tolerant tree ferns around. The combination of heat and dryness, however, will be the death of it; but unlike many highland plants it can withstand any amount of heat so long as it has enough moisture. It will do well if kept wet in the summer and also tolerates dry conditions well as long as it is cool. It is also said to do well indoors under cool conditions. Mine has also done well with our very wet winters here in western Washington, and it has tolerated temperatures down to 26°F as a young plant. It may be significantly hardier than this (one source, in fact, reports it has withstood 16°F in Britain), and as far as I am aware the limits of its hardiness have not yet been found. Unfortunately I lost mine in the exceptionally hot, dry summer of 1998.

Cyathea vieillardii-Native to New Caledonia and New Hebrides, this is a very fast-growing species, ultimately reaching 16' high, with an upright crown of fronds and an 8" thick trunk covered with shiny grey black scales. It will tolerate frosts down to 27°F, but, like C. atrox, must be kept rather dry to ensure survival of the cold. It would appear to prefer a partially shaded position in hot summer climates.

Cyathea woolsiana-This species is esteemed for its ease of growth and tolerance of a wide range of soils and conditions. The fronds may reach up to 8' long and are covered in very dark scales, and the trunk grows to about 12' high. It is related to Cyathea australis, but is probably somewhat less cold-hardy (guessing 26°F), and must be kept well-watered for it to look good. A native of moist forests in northeast Queensland, Australia.

Other species of Cyathea
The following is a list of some other Cyathea species that may prove reasonably viable in zone 9a or colder climates. Please note that the majority of these are tropical to subtropical in origin and their cold-hardiness is vestigal; that is, they are significantly hardier than they would need to be to survive in their natural habitat. To ensure their survival of winter cold, many of these should be kept rather on the dry side during frosts, and very well-insulated. Only a few on this page do not fall into this category.

Cyathea aramagensis - information coming someday, maybe

Cyathea atrox (Papua New Guinea) - This moderate sized tree fern related to C. tomentosissima hails from monsoonal high mountain forests (to 11,000' elevation). The trunk may reach a height of 18', with a 6" diameter; and the fronds seldom exceed 6' in length. At these high elevations, temperatures typically stay within a range of 42°F and 62°F, with occasional subfreezing temperatures. Freeze survival is aided by the fact that the temperature always rises above freezing during the day. It is probably about on par with C. cooperi for hardiness, but it should be kept dryish in the winter to ensure frost survival.

Cyathea baileyana (Australia) - This species is called "Wig treefern" because the crown is covered in skeletonised base pinnules which look like a mass of hair. It is rather slow-growing, but should be able to tolerate a few degrees of frost (probably around 27°F) and would be worth growing for the "wig." The fronds can reach about 8', and the trunk eventually reaches about 10' tall. Its introduction to cultivation may be slow since it is rather difficult to propagate. Pictured in D. L. Jones' Encyclopedia of Ferns.

Cyathea brevipinna (Lord Howe Island) - Mainly for interest I am including this very intriguing species whose features are all compacted to make a squat little treefern with short, densely crowded fronds. Perhaps even more baffling is the fact that no one has successfully raised these from spore, and in fact only one plant survives outside of its native habitat on a 2,600' high mountaintop on Lord Howe Island. Once the secret to its successful cultivation is found (if it is ever found), it could certainly make quite a nice novelty item for collectors, and might grow well in full sun in such places as Great Britain and the extreme West Coast of the United States. In my estimation it is likely that this species will tolerate a few degrees of frost, and its small fronds would make it easy to protect. Pictured in D. L. Jones' Encyclopedia of Ferns.

Cyathea carascana (South America) - This speices grows in Andean cloudforests at elevations up to 14,000'--possibly the highest altitude of any tree fern. It must certainly have some frost tolerance, but there is little information available about it.

Cyathea celebica (northern Queensland, New Guinea, Indonesia) - A very attractive species, whose 10' fronds take on a beautiful rigidity as they uncurl and expand, and whose stipes and upper trunk are covered in sharp black spines. Although a dweller of cool highland rainforests, it is said to adapt to a wide range of climates, and is has even proven slightly frost-hardier than C. cooperi (guessing 25°F), and should certainly be grown in other parts of the world. Closely related to C. leichhardtiana but more attractive and slightly faster growing.

Cyathea degaldii (Central America) - Hardy to at least 27°F.

Cyathea sp. 'floggacera' - Hardy to at least 27°F.

Cyathea fulva (Central and South America) - A little-known dweller of Andean and Central American cloudforests as high as 14,000', along with C. carascana. These are only two of many species from this region that would be worth trying for cold-hardiness.

Cyathea gleichenoides (Papua New Guinea) - A recently introduced species, this one grows at the incredible elevation of 12,400' where the usual temperature range is from about 37°F to 55°F. In order to get enough warmth for adequate growth, the crown has a specialized heat absorbtion mechanism, and it grows mostly in sunny moist sites. It typically inhabits open alpine grassland in the company of C. muelleri where frosts are common, some as severe as 18°F. Interestingly, at this elevation the night temperature is significantly colder at ground level than several feet above ground, and the youngest plants are subjected to the worst of the frosts. However, as with C. atrox, the daily temperature rise above freezing is crucial to frost survival, and I would not advise subjecting one to a severe frost unprotected in cultivation where freezes may persist for several days. So far it seems very adaptable, tolerating a wide range of situations and climates. Its cultural needs are probably similar to those of C. muelleri and C. tomentosissima.

Cyathea howeana (Lord Howe Island) - This robust tree fern grows an attractively scarred trunk to about 10' tall and 6" thick. The soft, light bluish green fronds and attractively scarred trunk of this species make it a worthy subject for cultivation where a more imposing substitute for C. cooperi is desired. It is similarly hardy (guessing 27°F), but may need a bit more heat than C. cooperi does to thrive. In addition, the thick stipes and veins of the fronds make the uncurling croziers remarkably large, which is a stunning sight when all of them uncurl at once in the spring. Pictured in D. L. Jones' Encyclopedia of Ferns.

Cyathea incisoserrata (Indonesia) - A rare, very beautiful species about which little is known. The trunk is about 1' thick and may grow to a great height. It is said to be hardy to 26°F, and therefore should be overwinterable in a zone 8b climate, but I would advise keeping it dry in the winter as with the other tropical latitude species. Presumably it grows at a rather high elevation.

Cyathea kermadecensis (Kermadec Islands, 500 miles east of New Zealand) - A fast and easily grown treefern, rather delicate-looking, whose hardiness is also probably similar to C. cooperi (guessing 26°F). It thrives in a sunny, humid situation, where it will develop an trunk up to 10' tall and about 4" thick, with an attractive crown of 6' long, dark green fronds. The uncurling croziers and stipes are covered in light brown scales.

Cyathea lepifera (Taiwan, Phillipines, Japan) - The twisted uncurling croziers of this species have earned it the interesting common name of "Flying spider monkey tree fern." The graceful, slender trunk, covered with scales near the crown, grows to a height of about 10', and the fronds generally reach about 8' long. It is beautiful and easily grown in cool conditions, requiring only generous amounts of moisture to thrive, and probably tolerating a few degrees of frost.

Cyathea macarthuri (Lord Howe Island) - A large fern similar to C. australis and C. dealbata. Exact hardiness unknown.

Cyathea macgregori (Papua New Guinea) - Grows at very high elevations with C. atrox, C. gleichenoides, and C. muelleri where it is subjected to some frost. More information forthcoming.
Cyathea manniana (East Africa) - This large, coarse treefern is found in gullies at moderate elevations. It is never found growing away from constant moisture and is probably quite cool-tolerant, but perhaps not very frost hardy.

Cyathea 'marleyi' - A very large, robust tree fern with robust scales that is probably hardy to at least a few degrees of frost. It was found in a nursery in Sydney, Australia owned by Judy and John Marley who are well known for their propagation of new and interesting species. Its true genetic origin remains unknown, but it is now being propagated in England and Germany as well.

Cyathea mexicana (Mexico) - This species is reported as thriving in Rossdohan in southwest Ireland. I suspect it is a cool cloudforest species with several degrees of frost tolerance. I have not been able to find out much else about it.

Cyathea milnei (Raoul Island, New Zealand) - A species rather similar to C. dealbata, and likely to be suited to the same conditions, except that it comes from a more tropical climate. The main difference is that it lacks the silvery undersides and stipes of C. dealbata, but it is a beautiful species nonetheless. It has a slender, dark, rough trunk and glossy green, lacy fronds. It may prove to withstand a few degrees of frost.

Cyathea muelleri (Papua New Guinea) - A little-known species from very high elevations (to 12,400') that grows with C. gleichenoides in open grasslands. It should tolerate overnight frosts down to 18°F, but see C. gleichenoides (above) for more detalis.

Cyathea novae-caledoniae (New Caledonia) - This interesting treefern has a large swollen trunk base, appearing from a distance as if it has a butressed trunk. It would probably tolerate a couple degrees of frost.

Cyathea podophylla (Taiwan) According to one source, this species has much more coarsely divided fronds than most Cyatheas resulting in a very different look (assuming the observed specimen was identified correctly). Coming from Taiwan, it might be a little bit cold-hardy.

Cyathea princeps (Central America) - This vigorous species looks quite a bit like C. brownii. Tolerates a few degrees of frost.

Cyathea thompsonii (East Africa) - This treefern comes from the same habitat as C. manniana.
Cyathea ursina (Central America)

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