The staghorn fern, Platycerium bifurcatum, a cold hardy subtropical fern

Platycerium bifurcatum, commonly known as the staghorn fern or elkhorn fern, is a modestly cold hardy subtropical epiphyte native to eastern Australia and parts of the the East Indies. Though no species of the genus Platycerium can be called truly cold hardy, this species is capable of handling temperatures down to 27 F (-3 C) with minimal damage. This article chronicles a plant I’ve grown in my yard in southern Japan for the last 11 years – a climate that has tested the boundary of its cold resistance many times.

P. bifurcatum is without a doubt the most commonly propagated member of this relatively small genus of epiphytic ferns (~18 known species). Like many ferns, these grow two types of fronds, fertile and infertile. The fertile fronds are elongate, leaf-like and bear spores, while the infertile fronds (also called shield fronds because of their flat, spreading habit) have no spores. In P. bifurcatum the fertile fronds are forked (bifurcate), looking like a deer’s antlers. The shield fronds grow more or less flat against whatever they are mounted on, and are roughly circular in shape. In time plants can form formidable clumps, spreading by “pups”, or offshoots that grow off small stems (called rhizomes), just below the shield fronds. Large clumps can grow to nearly the size of a small car!

Platycerium bifurcatum
Platycerium bifurcatum growing my garden in southern Japan, on the island of Kyushu.

P. bifurcatum is the most commonly available cold hardy staghorn fern. Only one other species is perhaps even more cold hardy, that being P. veitchii, which is said to handle 25 F (-4 C) without suffering. P. bifurcatum is reliably cold hardy down to 27 F provided that any given frost event is not terribly long, and the following summer is long and warm enough to allow it to recover fully. It can even take down to 24 F (-4.5 C), but events like this must be very sporadic, or the plant will not be able to recover.

I moved to my current house in the fall of 2004. It is situated on the edge of some moderately tall mountains (up to 3000 ft, or 900 m elevation), and is approximately 3 miles (~5 km) from the sea. The region rarely sees below 27 F, but can get down to 23 F (-5 C) on occasion. Winters are relatively short, starting in earnest by mid to late December, and finishing by late February. During this time frosts are frequent, but usually last no more than a day. Average temperatures during this period normally are 43-45 F (6-7 C) overall, with highs around 48 F (9 C) and lows just above freezing. Winter rain is frequent, but usually light to moderate. Snow is also common, but short lived, normally melting within a few hours of accumulating.

By contrast, both spring and fall are long and mild. The frost free months extend from early April through late November or early December. Spring is followed by a strong summer monsoon, lasting from early June to late July. Temperatures during this period are warm, averaging around 77 F (25 C), and most days are cloudy with at least some rain. From late July through mid September is the real heat, with daily highs averaging between 90-93 F (32-34 C), and lows only down to 79-83 F (26-28 C). This is a time of true tropical heat.

I mention all of this to give a context for describing how P. bifurcatum has performed in my garden over the last decade. Based on my results, you can get an idea of whether your climate will be suitable to try this one outdoors or not. I will add that my plant has received no special winter protection, not even from snow. So lets see how it has progressed through the years, and what setbacks it has also endured.
Continue reading “The staghorn fern, Platycerium bifurcatum, a cold hardy subtropical fern”

The ribbon fern, Pteris cretica, and two brake fern buddies

Southern Japan is home to three common species of brake fern in the genus Pteris: P. cretica, P. multifida, and P. nipponica. Pteris cretica is perhaps the best known of these, also called ribbon fern in the horticultural trade, and can be seen in almost any nursery or big box store selling tropical foliage plants. It isn’t a truly tropical species in Japan however, and neither are its two companions. They are in fact at home in the rocky woods of Japan’s warm temperate forests – warm being relative since winters here can get rather cold, and even snowy at times.

All three are a common sight in my area, just on the outskirts of Fukuoka City, on the island of Kyushu. By far the most often seen is P. multifida since it is a veritable weed in these parts, growing out of just about any crack in a wall – natural rock or concrete. It is also the smallest in stature of the three. The other two are closely related, to the point that one needs to look at them carefully to see the differences. Never are any of them very far from rocks, or seeps of water, and yet they are neither bog plants, nor true lithophytes. I’ll tackle them one by one, starting with the weedy species, P. multifida.

Pteris multifida plant
Pteris multifida is perhaps the most common and widespread of the brake ferns in Japan.

P. multifida is an evergreen, clumping fern commonly seen growing in cracks in rocks, rock walls, and also disturbed soil. Its fronds are of two types, spore bearing and sterile. Their overall shape is similar except that the spore bearing fronds are perhaps twice the size of the sterile ones and all parts are much more narrow and elongated. This fern is once pinnate, with pairs of simple pinnae extending off the main stem, or rachis. The pairs of pinnae usually number between 4 or 5 per frond with the base pair being the shortest, and subsequent pairs being longer, and again becoming shorter toward the end. The terminal pinna is typically very long and singular – a trait common to many Pteris species. Each pinna is rarely more than one cm wide. The base of the stem (also known as the stipe) as well as the rachis are smooth, scale-less, and brown in color.

An interesting feature of this species is a wing-like structure growing along the length of the rachis between the pairs of pinnae. Close examination shows these wings to in fact be extensions of the uppermost pinnae growing clear down the rachis to the next pair and terminating there. The pinnae are presented in a flat plane in some individuals while they can be very wavy in others. The margins of the pinnae are roughly toothed, but not lobed. Sterile fronds grow between 12-30 cm in length, while fertile ones can be half again that length. Typically these are small ferns though, with a total height of not more than 20 cm on average. The fertile fronds tend to grow more vertically, while the sterile ones essentially hang parallel to the ground. Both frond types usually are a pale green color and slightly shiny.

Pteris cretica albolineata
The lovely variegated Pteris cretica ‘albolineata’ has been mass produced and marketed across the world. It is commonly called the silver ribbon fern.

Continue reading “The ribbon fern, Pteris cretica, and two brake fern buddies”

An odd woodland fern, Japanese grape fern, Botrychium japonicum

Japan is home to an astounding array of fern species, including the grape ferns or moonworts, genus Botrychium. Two commonly seen species in Japan are B. japonicum and B. ternatum, both winter green, summer dormant plants. This article deals with the former, a larger plant in all aspects.

B. japonicum is a winter green species rarely more than 30 cm tall. It has two distinctly different looking fronds. The one that looks like a typical fern frond is called the trophophore and is sterile, while the other one bearing the spores is the sporophore. New growth of both frond types occurs in late summer and early fall. The trophophore is 3 times pinnate. Just after emerging it branches off from the sporophore and separates again into three equal sections, each growing up to a length of 10 or more centimeters. The entire blade is roughly triangular in shape; 20 cm or less at its base and tapering down to its end. The pinnae are toothed sharply and are highly veined. The stipe has a light coating of small scales about halfway up and then becomes naked.

Botrychium japonicum frond
The sterile frond of Botrychium japonicum is divided equally into three sections and is three times pinnate.

The sporophore rises to twice the height of the trophophore and ends in a cluster of opposite branched stems bearing perfectly round spore cases. The lowermost stems are divided again into smaller opposite branches and are long, up to 3-4 cm in length each. These stems progressively get shorter further up and half way up the entire cluster they cease to be branched. The small spore cases group tightly near each other on these stems, giving the appearance of a cluster of tiny grapes (actually, they look like fish eggs to me!). They start out bright green, but eventually turn yellowish, then orange and finally brown with age.

Botrychium japonicum can be found on Honshu, Shikoku, and Kyushu in Japan as well as Korea, Taiwan, and China. It is most commonly seen in moist deep woods in moderate to heavy shade. Occasionally it is found in conifer plantations, but most often in mixed broad leaf forests. On Kyushu it is usually seen at mid level elevations (~300-600 meters). Plants occur singly or or in small, loose groupings.

This is a strange group of ferns very unlike most except their near cousins, the adder’s tongue ferns, genus Ophioglossum. The best time to see them is in mid fall just after the fronds have emerged. This fern is peculiar in that it seems to prefer mature hardwood forest, or at the very least old plantation forest. You never see it in young plantations. It is more curious than lovely, but I’m always pleased to find one, especially since they are seen only here and there. I’m always a bit startled when I come up on a group since they “magically” appear in places that were empty all spring and summer, being a summer dormant species. Moreover, plants can remain dormant underground for years before appearing again, so any given plant may not be seen for several seasons.

Botrychium japonicum adult
Botrychium japonicum is at its best in the months of October and November, just after emerging.

The genus name, Botrychium, is from the Greek word botrys meaning “grape”, a clear reference to the cluster of tiny spore cases at the end of the fruiting frond. The Japanese name is oohanawarabi, meaning “large flowering bracken” from the words oo = big, hana = flower, and warabi = bracken. Bracken is a term used in the west primarily for the genus Pteridium, but it is more broadly used in Japan with the word warabi for any fern that resembles that genus.

Botrychium japonicum sporophore
The sporophore is the fertile frond, producing the spore, and the reason why these ferns are commonly called “grape ferns” or “flowering ferns”.

Perhaps the plant seems to be a flowering bracken because of the large sporophore which is quite showy when the spore sacs turn yellow . The reason it is called “big” is that it is larger than the other common species in Japan, B ternatum, fuyunohanawarabi (“winter flowering bracken”).

This fern may present a problem in cultivation, though I’ve never tried growing any Botrychium species. Some say they can be transplanted by digging wild plants up with a good section of earth and placing it in a similar woodland. Part of the problem may lie in the fact that these ferns are strongly associated with a fungus symbiont, and may require at least some of their nourishment from them. Some species of this genus have highly reduced trophophores, potentially increasing that dependence. These are therefore probably best appreciated in their native homes, though the more insistent fern lovers may want to try them. It is also possible to try germinating spore provided the correct fungal symbiont can be grown alongside – undoubtedly another difficult process.

A cool species to see in the wilds of Japan, but not a very likely candidate for the garden. This odd genus of woodland fern, though widespread and diverse over much of the northern hemisphere, largely remains an enigma for gardeners.


Videos about ferns

Have a look at these videos anytime you like. This post contains all the videos I have on ferns and will be updated as new videos are produced.

Epiphytes of Kikuchi Gorge – while this video is about all the epiphytes I’ve seen at the lovely Kikuchi Gorge in Kumamoto Prefecture, Kyushu, it contains many ferns and fern relatives. Here you get to see a fantastic epiphytic fern community in the heart of Kyushu’s temperate rain forest.

The Genus Coniogramme in Japan – the bamboo ferns – this video shows the two species of Coniogramme in my area, C. japonica and C. intermedia, as well as the variegated form of C. japonica (f. flavo-maculata) and the natural hybrid between the two species, C. x faurei. Enjoy these beautiful ferns in their native woodlands.

Japanese Fern Hunt, the Brake Ferns, Genus Pteris – focusing on all the common species of Pteris found in the Fukuoka City area, including three similar species, P. cretica, P. multifida, and P. nipponica, two large species, P. wallichiana and P. excelsa, and one oddball, P. dispar. Here you see them in the native habitat and also get a tutorial on how they can be differentiated.

Epiphytic Ferns of Southern Japan – here’s a guide to the more common epiphytic and lithophytic ferns I’ve found in the Fukuoka City area. Epiphytic ferns are becoming rarer in Japan, especially the coveted species, but most in this video thankfully remain quite plentiful.


A shield fern of southern Japan, Ctenitis maximowicziana

The warm temperate forests of southern Japan are home to a shield fern who’s most notable feature are the scales that cover its long stipes. This fern is so scaly in fact that they have earned it one of its Japanese names, the grey haired fern. The newly emerging croziers come up like a ball covered in so many of them that indeed it does look like the head of an odd white haired creature.

Ctenitis maximowicziana crozier
The emerging crozier of Ctenitis maximowicziana looks like some odd white haired creature on the forest floor.

Ctenitis maximowicziana is a medium sized to large evergreen fern growing from a short, creeping rhizome. The fronds are few (usually five or less) and ascend in a graceful arc. They are a light green color and three times pinnate. Each is from 50-100 cm long and 30-50 cm wide. The stipe accounts for one quarter of the length of the frond and is covered in large white and brown scales. These continue up the rachis nearly to the frond’s end, and also extend out onto the pinnae. The sori are round and are in pairs around the vein (called the costule) of each pinnule. Plants occur in small groups or singly.

This fern is found in the warmer regions of Japan from Honshu (most commonly in the Kanto region and westward, but with a northern outpost in Akita Prefecture), Shikoku, Kyushu, and the islands south of Kyushu including Okinawa. It is also reported from Taiwan and China. It seems to prefer moist ravines near water, but not at the water’s edge. This lovely woodland fern is found in both natural forests and in conifer plantations from 300-500 meters elevation on Kyushu.

Without a doubt, the most outstanding feature of this shield fern are its scales. From the time the croziers emerge in spring and throughout the frond’s life, the numerous lovely white and brown scales of the stipe and rachis are undeniably attractive. In spring the emerging crozier is brilliant lime green and literally covered with these, creating a unforgettable image. The scales brown with age and look best in the spring. Though not uncommon in Fukuoka, this fern is not frequently seen either, occurring in scattered areas. Without a doubt, this is one of Fukuoka’s most beautiful ferns.

Ctenitis maximowicziana in habitat
The fronds of Ctenitis maximowicziana hang in a graceful arc. The stipe and rachis are completely covered in white and brown scales that have earned it one of its names in Japan, the grey haired fern.
Ctenitis maximowicziana stipe
The scales up close.

The genus name Ctenitis means “comb” from the Greek word kteis. The species epithet, maximowicziana, is in honor of Carl Johann Maximowicz (1827-1891), a Russian botanist and curator of the Saint Petersburg Botanical Gardens. This fern is in the shield fern family, Dryopteridaceae, and is placed in the genus Dryopsis by some authorities. In the field it may be confused with another fern, Thelypteris torresiana, but that species lacks the tell tale scales of C. maximowicziana.

The Japanese name, kiyosumihimewarabi, means “noble princess bracken” from the words kiyosumi meaning “pure or noble”, hime meaning “princess”, and warabi the Japanese word for bracken fern. Yet again another obscure name. It also has an alternate name, shiragashida, coming from the word shiraga meaning “white or grey hair” and shida meaning “fern”, a reference to the white and brown scales found on the stipe and rachis. At least that makes sense!

Ctenitis maximowicziana spores
The sori of Ctenitis maximowicziana occur in pairs along the costa of each pinnule.

I’ve never tried this one before, but I suspect it shouldn’t be that challenging in a moist and shady garden. Given its distribution, it should be cold hardy to USDA zone 8-10 (perhaps a bit lower with adequate protection and careful siting).

As with many obscure Asian species, this woodland fern is virtually unknown in cultivation in the West. In truth, it is little known in Japan, except by fern enthusiasts, and is never seen as a garden subject. That is too bad since this graceful fern would be a great addition to warmer woodland gardens the world over.


The epiphytic ferns of Kikuchi Gorge, Kumamoto Prefecture, Japan

Kyushu’s naturally wet climate and relative warmth provides near perfect growing conditions for epiphytic plants and few places rival one of its greatest natural wonders, Kikuchi Gorge in northern Kumamoto Prefecture. This gorge drains an upland plateau averaging between 600-800 meters elevation. The water of the gorge’s river, as well as many of the region’s waters, are some of the purest in Japan since their source is subterranean, and therefore is filtered through kilometers of porous rock.  The entire area is in fact the base of an ancient volcano that blew its top thousands of years ago, leaving behind one of the world’s largest extant calderas, Aso Caldera, measuring 25 km in diameter north to south, and 18 km east to west.  Though the mountain lost most of its mass in the distant past, it remains active.

Along the watercourse of the gorge are numerous waterfalls and old growth forest.  This forest is most famous for its fall foliage, in particular its maples and zelkovas, but also is home to a host of many types of fern and their allies, the clubmosses and spikemosses.  Without a doubt, historically the gorge boasted many epiphytic orchids as well, but these are few and far between nowadays, most likely having been collected out years ago.  In the 60’s, 70″s, and 80’s, as Japan’s economy flourished, the desire for rare species reached a fevered pitch and many wild areas were denuded of their most precious citizens – orchids lead the way, but many others were effected.  Luckily, most ferns were left alone, or were able to reproduce fast enough to maintain viable populations.  Kikuchi Gorge remains a lovely example of epiphytic laden, riparian old growth forest.

Tengu Falls, Kikuchi Gorge
Kikuchi Gorge is home to many spectacular waterfalls including this beauty, Tengu Falls. The twigs of the overhanging branches are covered in mosses and beard lichens.

Epiphytes seem to grow most luxuriantly on horizontal branches where leaves, animal droppings, and other organic material can build up.  Two commonly seen ferns in the gorge are Loxogramme salicifolia and Lemmaphyllum microphyllum, as seen in the picture below.  The long simple fronds belong to L. salicifolia while the small oval fronds are of L. microphyllum. The latter is a very common species throughout the low mountains of Kyushu, while the Loxogramme is more rare.  In the Fukuoka City area I’ve seen L. salicifolia growing strictly on rocks, but in Kikuchi the humidity is so high that it ventures out onto the trees as well.  Like many other epiphytic ferns, this species shrivels when dry, only to rebound once the rains come again.

Loxogramme and Lemmaphyllum
Epiphytes favor horizontal branches. Here you can see two common epiphytic ferns of Kikuchi Gorge, Loxogramme salicifolia and Lemmaphyllum microphyllum.

Continue reading “The epiphytic ferns of Kikuchi Gorge, Kumamoto Prefecture, Japan”

The autumn fern, Dryopteris erythrosora

Japan and much of southeast Asia’s broad leaf evergreen forests are home the autumn fern, Dryopteris erythrosora, who’s claim to fame is the brilliant red of its newly grown fronds.  This is one of the most commonly grown Japanese ferns due to its beauty and ease of cultivation.  In the woods near my home on Kyushu, it is a near weed.

Dryopteris erythrosora habitat
The autumn fern is at home in just about any forest type on Kyushu, and ventures out to roadsides as well. Here it is growing in a hinoki plantation forest.

Dryopteris erythrosora is a medium to large sized evergreen fern with a short, creeping rhizome.  The glossy fronds are twice pinnate with the pinnules ending in a pointed tooth and are 30-130cm long and 20-40cm wide.  The emerging croziers are bright brick red, and the newly grown frond retains this color for a short time before assuming the dark green of a mature frond.  The stipe is covered with many brown scales and accounts for 1/3 of the frond length.  The brick red sori are round and numerous, occurring in pairs on the pinnae’s lobes on opposite sides of the costa. The indusia are kidney shaped.

Dryopteris erythrosora new frond
As the new frond of Dryopteris erythrosora expands it has a deep, brick red color. This is why the Japanese call it benishia, meaning “red fern”.

In Japan D. erthrosora is found in the broad leaf evergreen forests of Honshu, Shikoku, and Kyushu.  It is also native to China, Korea, and the Philippines.  On Kyushu it is a common fern at almost any altitude being seen in moist forests, tree plantations, cut over hillsides, growing in rock walls, and roadsides, from 0 to 1000+ meters.  It is a clumping fern found in loose colonies.

Dryopteris erythrosora sori
The sori of Dryopteris erythrosora are bright brown-red. In fact, erythrosora means “red heap”, no doubt in reference to these.

This is certainly one of Japan’s better known ferns often sold under the name autumn fern because of the rich red color of the new fronds.  The Japanese name literally means “red fern”, alluding not only to the emerging crosiers and newly grown fronds, but also to the young ripe sori that too are bright red-brown.  This plant is common throughout my local area in just about any woodland or roadside.  In time it can grow into large clumps with fronds over a meter long, but most often is it more modest in size.  Without a doubt, the most striking feature of this plant are the newly emerged fronds starting out a rich red color, then turning lime green, and finally dark green with maturity.

Dryopteris erythrosora half grown frond
The newly grown fronds of Dryopteris erythrosora retain much of their red color for several weeks after flushing.

Its Japanese name is benishida, meaning “red fern” from the words beni (crimson or red) and shida (fern).  The Latin species epithet, erythrosora, comes from the Greek words “erythros” meaning red and “sori” meaning “a heap”, no doubt a reference to the round, red sori of this species.

Autumn fern is easily grown in just about any garden setting except full blazing sun.  It seems to adapt well to just about any soil as long as it is free draining and not too basic in reaction.  It should be fully cold hardy from UDSA zones 5-10, though it may defoliate in colder zones.  This is not a picky species and worth growing for the spring fronds alone.

Dryopteris erythrosora crozier
Even the crozier of Dryopteris erythrosora shows off red color – this will deepen as it expands.


Two Japanese tassel ferns, Polystichum polyblepharum and P. tripteron

Japan is home to a number of Polystichum species, but two dominate in southern Japan’s forests, P. polyblepharum and P. tripteron.  The former is common at low elevations here in Fukuoka, belying its preference for the warmer parts of Asia, while the latter is a straggler to Japan’s southern forests, more suited to the cold temperate woodlands of northern Asia.

Polystichum polyblepharum is an evergreen fern with a short creeping rhizome that sometimes forms a small trunk. The frond is twice pinnate, growing up to 100 cm long.  They grow in a rosette forming a near perfect circle.  The pinnules are boot shaped and have slightly toothed margins with a pointed tip.  The round sori are in rows along the costa.  The thick, fleshy stipe is covered in large cinnamon brown scales and accounts for about one quarter the length of the frond. The unfurling croziers hang down at their tips, giving them a drooping, tassel-like shape typical of this genus. While this fern can create offsets from the rhizome, the plant is more commonly seen growing as a  single rosette of fronds.

Polystichcum polyblepharum croziers
The emerging croziers of Polystichcum polyblepharum grow all at once in early spring.

In Japan it is widespread from Honshu and southward.  It is also found in South Korea, and the warmer parts of China.  In the Fukuoka area it is found in moist woodlands from near sea-level to over a 1000 meters. This is one of the most commonly seen woodland ferns in Fukuoka and indeed much of the warmer parts of Japan.  One of its most distinguishing characteristics are the large cinnamon colored scales that cover the stipe and rachis.  They are particularly noticeable when the croziers just emerge.

The half grown fronds hang down as they elongate, giving this fern its English common name, the tassel fern.  The overall visual impression of this species is very pleasant since it forms perfectly circular rosettes of fronds up to 2 meters across in vigorous specimens, but more commonly half that size.

Polystichcum polyblepharum half grown frond
The half grown frond of Polystichcum polyblepharum dangles downward which earned it the name “tassel fern”.

The upper surface of the pinnae are a beautiful,  glossy green that gives off a bluish sheen.  A multitude of white hairy scales cover the lower pinnae surfaces and give the plant its Latin name, polyblepharum, meaning “many eyelashes”, however they are not easily seen by the naked eye.

In truth there are a number of near look alike species from this genus, and to tell them apart you have to closely examine their scales and pinnae.  If that weren’t bad enough, members of this genus hybridize readily, thus compounding identification.  I have decided to avoid all that and simply lump them all under this species.  A lazy approach, but one has to be careful how time is spent in life!
Continue reading “Two Japanese tassel ferns, Polystichum polyblepharum and P. tripteron”

The common lace fern of Japan, Sphenomeris chinensis

An unusual and attractive plant that doesn’t quite look like a fern is Sphenomeris chinensis.  While few westerners have even heard of this fern, it is in fact a common plant in much of east Asia and Polynesia.  Its 3-pinnate fronds and tiny wedge shaped pinnules give it a uniquely delicate look and has earned it the common name lace fern.

S. chinensis is a fairly small evergreen fern with a short creeping rhizome.  Fronds are produced throughout the warm months and are 3 times pinnate giving them a very fine textured look. Frond length is variable depending on the exposure to the sun with long fronds growing in shadier locations.  They can be anywhere from 10-100 cm long and 8-20 cm wide, but typically don’t grow more than 50 cm long.   Although the pinnae grow in an alternating pattern, there often exists a basal pair of pinnae that are separate from the next pair further up the rachis by several centimeters.

Sphenomeris chinensis in habitat
Sphenomeris chinensis typically grows on near vertical slopes in bright shade.

These basal pinnae are the largest on the frond and the rest get progressively smaller as they approach the tip of the blade giving the frond a long triangular shape.  The tiny pinnules are wedge shaped with the wide end at their terminus.  At the end of the pinnules the small oval sori are born singly or in pairs. The reddish-brown stipe is completely scaleless and hairless, and accounts for nearly half of the frond length on large fronds.  These ferns are commonly seen growing in loose colonies on nearly vertical slopes.

S. chinensis is found in the warmer areas of Japan including Honshu (Niigata, Yamagata, and Fukushima Prefectures and southward), Shikoku, Kyushu, the southern islands to Okinawa, as well as Korea, Taiwan, China, Indochina, the Philippines, Papua New Guinea, India, Nepal, and the South Pacific Islands (Hawaii, Cook Islands, Tonga, Marquesas Islands, and Samoa).  It perhaps has been reported from Madagascar, but this may be a mistaken record.  It is listed as a potential exotic weed in New Zealand.

Sphenomeris chinensis crozier
The emerging crozier of Sphenomeris chinensis has an elegance and grace all its own.

This lovely little fern can be seen in any moist forest in moderate to light shade, however it  is also found on sunny roadsides in thick growth of grasses, herbs, and small shrubs.  It seems to like to colonize raw earth in cuts created by roads, paths, and landslides, and also on natural rock outcrops where moisture is abundant.  Seen from near sea-level to 1000+ m, but most common in low to mid elevations, 50-600 m, on Kyushu.

At first glance with its 3-pinnate fronds it can seem to be a Selaginella, but a closer look shows that it is indeed a type of fern.  The frond’s shape is unusual, especially with its numerous, tiny wedge shaped pinnules.  The overall appearance of the fronds is very soft and pleasing.  It is mostly found in bright locations, from sunny roadsides to bright woods along stream banks, and is a common species in the Fukuoka area.  In the fall and winter the fronds can get purplish if in an exposed position, thus adding to its charm.

Sphenomeris chinensis frond
The 3-pinnate frond of Sphenomeris chinensis gives the plant its common name, lace fern.

Happily, it is easy to grow.  I’ve had one in the garden for several years now and have given it no attention except to make sure that surrounding plants don’t out-compete it.  In fact the only problem I’ve had is that it grows too well, so it is necessary to prune back larger fronds from time to time.  This is a fern that requires bright light to grow well, and also needs a well drained, yet continuously moist soil.  In nature you never see it in a flat place, so drainage is sharp.  It is not fussy, so any reasonable woods loam is fine for this one.  One drawback is its lack of cold tolerance, perhaps only hardy to USDA cold hardiness zones 7-10.  It is a lovely compact growing fern if grown in bright light, but more airy and large in darker conditions.

The pinnules of Sphenomeris chinensis are wedge shaped, hence the genus name Sphenomeris, meaning “wedge part”. Also note the oval sori at their ends.

Its Japanese name is horashinobu, meaning “cave Davallia” from the words hora (“cave”) and shinobu, the name for the epiphytic fern Davallia mariesii, which it not only resembles, but is related to.  Another typically obscure Japanese name!  The genus name, Sphenomeris, is from the Greek words spheno meaning a wedge and meris meaning a part, probably referring to the wedge shaped pinnules.

I have only praise for this lovely fern.  If you can get one, do so.  They are lovely to look at, easy to accommodate, and compact in size – in short, a must have plant for the serious fern collector or warm climate gardener.


Zenmai, Japan’s cinnamon fern, Osmunda japonica

An edible fern that is well known to all Japanese people is Osmunda japonica, called zenmai in the Japanese language.  This widespread fern is in fact not only delicious, but a lovely plant in and of itself.

Osmunda japonica is a large deciduous fern with a thick rhizome that occasionally can form a small trunk (caudex).  There are two frond types that show extreme dimorphism:  the spore bearing sporophylls and sterile trophophylls.  The sporophylls emerge concurrently with the trophophylls and grow vertically to a height of 30-70cm tall.  Approximately half way up these specialized fronds opposite pairs of branches form (analogous to the pinnae) and off these are paired spore bearing structures – highly modified pinnules.  These are literally covered in cinnamon brown, naked spores, hence giving many in the genus the name cinnamon fern.

Osmunda japonica sterile frond
The sterile fronds of Osmunda japonica look similar to the North American species Osmunda regalis, but are a bit more stout.

The trophophyll by comparison looks much like a typical fern frond and is twice pinnate growing anywhere from 60-100cm long and 40-60cm wide.  The pinnae grow in opposite pairs off the rachis and the oblong pinnules occur alternately and usually are unlobed.  The stipe accounts for a third of the length of the frond.  The impressive crosiers emerge covered in whitish-brown hairs, but these soon fall off leaving the stipe and rachis completely smooth.  Plants usually occur as a single growth with no offsets, but often forming extensive colonies.

This species is widespread on the mainland islands of Japan, also Russia (Sakhalin), Korea, Taiwan, China, Indochina, and the Himalayan Mountains.  It is common in moist to wet forests, field-like slopes that are annually cut, seepage slopes, road cuts, swales, and ditches.  On Kyushu it can be found at all elevations, 0-1000+ meters.

O. japonica is one of the better known ferns in Japan due to the emerging crosiers that are collected each spring as a seasonal food.  Traditional foods in Japan are deeply linked to the seasons, no matter what type; roots, herbs, shoots, and even fish.

Osmunda japonica fertile fronds
The fertile fronds of Osmunda japonica are similar to other members of the genus and are why one common name for them is “flowering ferns”.

In spring it is common to see cars parked along roadsides, and people out foraging for their favorite herbs.  Zenmai is often eaten with takenoko (bamboo shoots) taken from the huge bamboo species called moso, Phyllostachys pubescens.  Each spring my neighbors come to my door with both takenoko and zenmai as a seasonal gift.  These are prepared by boiling them in a pot with water and some seasoning such as shouyu (soy sauce), su (vinegar), and sato (sugar) until soft.  As my girlfriend says, “it is a taste of spring!”  Another commonly eaten fern in spring is warabi, Pteridium aquilinum, a species that is a known carcinogen.  I’ve heard that zenmai is not as dangerous, but being on the safe side, I only consume either in any quantity in the spring, and just a couple of times a year.

The fern itself is very common, being found just about anywhere there is adequate moisture.  It is very reminiscent of its relative O. regalis, but is more stout in stature.  The conspicuous spore bearing fronds emerge alongside the sterile fronds in mid spring and are quite lovely in and of themselves, and thus earning this type of fern the nickname “flowering ferns”.  In fall their foliage turns a bright yellow and is attractive for a short time.  It can occur as a single clump or form extensive colonies, but always in the company of other fern species.

I’ve grown this one for many seasons now.  It appears to be pretty easy in a lightly shaded to partially sunny location with evenly moist soil.  Any good loam will do for these just fine.  They are not wetland dependent like O. regalis.  Given their wide natural distribution, I’d say they can be grown over a broad range of climates (USDA cold hardiness zones 3-10).

Croziers of Osmunda japonica
The croziers of Osmunda japonica are a common food in Japan in the spring and are called zenmai.
Zenmai is the name given to both the fern and the fiddleheads which are a spring food throughout Japan.

The Japanese name, zenmai, means a “spring, coil, or mainspring” and probably is a reference to the shape of the crosier which looks like a coiled spring.  This word is used in Japan to mean the crosier as a food eaten in spring or the fern as a species.

I think this cinnamon fern is a lovely addition to any suitable garden.  While it is similar to the more commonly known O. regalis, it is no less lovely, and possibly easier to grow as well.   The hardest part will be finding plants for sale on the international market.

Osmunda japonica fall fronds
In the fall Osmunda japonica puts on a brilliant, but brief display.