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.


4 Replies to “The common lace fern of Japan, Sphenomeris chinensis”

    1. I’m sorry, I don’t. Many of the ferns on my site are not grown as they’re wild forms in Japan. Only are the odd forms grown – ones with leaf variegation, special leaf forms, etc. I’ve never seen anyone selling spore though, just mature plants. In the future I’ve considered selling spore overseas, but I’m not sure it is economically viable. My garden is small, so I’d have to harvest from the wild which is very time consuming, and you have to time things correctly. Is it worth the work in the end? Maybe, maybe not.

  1. Hi there. I just acquired a sphenomeris a month ago. I kept it moist the way I kep my maidenhair fern moist – by topping up my saucer all the time. But I’ve noticed there are dry crispy ends on my sphenomeris. Perhaps I am not doing it right. Any advice for me? Maybe I should be watering everyday instead of taking the shortcut.

    1. Interesting. The Sphenomeris I’ve seen here grow on near vertical surfaces such that the substrate is never perpetually wet, just evenly moist. That said, I’m sure you could grow this species hydroponically. My guess is that the growing medium has gotten a bit sour from the constant moisture, or the fern is sensitive to something in your water. I’d check to see if the growing medium looks and smells OK, then try watering it without use of the saucer. If that doesn’t work, perhaps repotting it into fresh medium might help. Locally they grow in loamy acidic soil that is free draining, but always moist. Good luck!

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