Japan’s common twayblade, Liparis nervosa v. bituberculata

The warmer parts of Japan are home to a circumglobal species of orchid, Liparis nervosa v. bituberculata.  This small, yet intriguing, plant is one of the most common orchids in Japan’s warm temperate and subtropical forests.

Liparis nervosa v. bituberculata is an evergreen orchid usually supporting two and sometimes three opposing leaves off an elongate psueudobulb.  The plant is small, no more than 20 cm tall, the flower spike included.  The psuedobulb is fleshy, purple to green in color, above ground, and grows up to 6 cm tall and 1.5 cm wide.  The leaves grow from nodes along the pseudobulb and are deeply ribbed, growing from  5-15 cm long and 3-8 cm wide. Unlike other members of this genus, the leaves aren’t glossy looking on their surface, but rather ribbed looking from the deep set veins in them.  They often have a crinkled look about them as well.

Liparis nervosa v. bituberculata habitat
Liparis nervosa v. bituberculata flowering on a sand dune pine forest, Higashi Ward, Fukuoka City, Kyushu, Japan.

A branch less flower stalk grows from the tip of the pseudobulb to a height of no more than 20 cm, and usually much less. It supports 5-20 purple-black flowers born in sequence, although most or all can be in flower at one time. Each flower is small, no more than 2 cm across.  The flower parts are purple-black overall, but are green at their points of attachment.  The pollina are bright green, almost electric looking.  The sepals are held in a triangular arrangement while the petals are thinner, almost peg-like, and are sharply back facing.  The broad lip is curled backward and has a deep valley down its center, giving it a distinct bisymmetric shape.  The flowers may be at least partially autogamous (self pollinting) since most flowering plants will set seed.

The variety bituberculata is found throughout the warmer regions of Japan including all of the southern islands down to Okinawa (where it is threatened), Kyushu, Shikoku, and Honshu as far north as Fukushima Prefecture on the Pacific coast and Fukui Prefecture on the Sea of Japan side.  It is likely to occur also in South Korea and parts of China.  L. nervosa is found virtually across the globe in tropical to subtropical regions with suitable habitat:  China, Taiwan, the Philippines, Indochina, India, tropical Africa, tropical South America, Central America, the West Indies, and peninsula Florida.

Liparis nervosa v. bituberculata flower
The flower of Liparis nervosa v. bituberculata is rather pretty up close, but is small, no more than 2 cm across.

Not surprisingly, it has been collected and named on many occasions such that numerous synonyms exist worldwide.  In Japan v. bituberculata is found in many environments, but always in forests, from moist broad leaf evergreen woodlands, to conifer plantations, and even pine forests on seaside sand dunes. On Kyushu it is restricted to lower elevations, from sea level to ~600 meters.

This has to be the most common terrestrial orchid in the Fukuoka area, and also the most cosmopolitan in habitat choice.  It is found in almost any forest setting and also at any elevation up to about 600 meters.  V. bituberculata is limited to Japan (possibly Korea and China, but I have no specific reference), however L. nervosa is pantropical in distribution, being found on every continent in or near the tropics with the exception of Europe and Australia.  The typical form of  L. nervosa is also a much larger plant by comparison, up to 60 cm tall, three times the size of Japanese plants.  V. bituberculata is found from subtropical to warm temperate climates within Japan, making it the most north growing variety of this wide ranging species.

Liparis nervosa v. bituberculata flower spike
The Japanese name for Liparis nervosa v. bituberculata is kokuran, meaning “black orchid”.

In my experience it is the only woodland species that actually prefers disturbed sites, most notably tree plantations.  Here it grows into moderately large clumps with as many as 5-6 flowering growths.  The most vigorous colony I’ve ever seen was on the backside of large sand dunes next to the beach growing in a black pine (Pinus thunbergii) forest.  The ground remains perennially moist there but being pure sand, the drainage is perfect.  In an area no bigger than a small room, I’ve counted over 90 flowering stems, a density far beyond the norm. Along with Cymbidium goeringii, it is one of the few terrestrial orchids capable of growing in the depths of moso bamboo groves (Phyllostachys edulis).

The flowers are almost black in coloration, but close inspection reveals them to be very dark maroon, as with all supposedly “black orchids”.  The Japanese name, kokuran, in fact means “black orchid”.  The plant has the curious habit of being able to re-root itself if becomes severed from its roots (much like an epiphyte).  Plants growing near streams or on roadside banks often get washed away during the flooding rains of summer only to reroot further away.  While this may seem remarkable, many Liparis species, especially deciduous ones, typically grow an entire new set of roots annually, and so can be stored as rootless bulbs in the winter months.  Being so common in Japan, its future is bright even in this highly developed country.

Liparis nervosa v. bituberculata cultivated plant
Liparis nervosa v. bituberculata takes well to the open garden. This one is in the author’s garden in Fukuoka, Japan.

Not surprisingly this tough little species isn’t difficult to grow.  The only requirements are that it has a well draining mix, stays evenly moist, receives light shade conditions, and doesn’t get too cold.  I’m not sure just how cold hardy it is, but given its habit of growing at low elevations, I’d say it won’t tolerate temperatures below -5 to -7 C (mid to low 20s F) for extended periods.  If you can get a hold of Japanese plants, you may be able to grow them unprotected in USDA cold hardiness zone 9 or higher, and maybe even in the warmer end of zone 8.

Each year the old roots are essentially dead by the following spring and serve only to hold the plant in place, a common feature of many Liparis species.  Still, repotting or replanting is not necessary every spring, but doing so wouldn’t harm them either.  Although all of my plants set seed each year, I’ve yet to see any volunteer seedlings in the garden.

Here is a cute botanical species that deserves a place in the greenhouse or warm climate garden.  It won’t bowl you over with its beauty, but it may fascinate you at a closer look.  For the simple reasons that it is easy to keep alive and is a terrestrial orchid to boot, are enough to try this one out.

Liparis nervosa v. bituberculata seed pods
Liparis nervosa v. bituberculata may be self pollinating since seed pods are frequently set with this species.

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