Endangered Calanthe orchids from the Izu Islands, C. izu-insularis and its hybrids

The Izu Island chain spreads south of the Kanto region of Honshu for more than 400 km in a near north-south orientation, bounded on the west by the Philippine Sea, and to the east by the Pacific Ocean. They are know for their distinctive culture, dolphins, beaches, and volcanic activity, but there also exists an endemic orchid on three of the islands that is found nowhere else in the world, the fragrant Calanthe, C. izu-insularis.

Here too is the closely related species, C. discolor, and the resulting hybrid between the two, C. Koozu. Today both C. izu-insularis and C. Koozu are rare as hen’s teeth in their native forests, however, Calanthe enthusiasts have managed to successfully propagate them by seed in large quantity, thus ensuring their continued survival.

Calanthe izu-insularis flowers
While the flowers of Calanthe izu-insularis are attractive, they are collected by Japanese growers for their incredible floral fragrance.

Calanthe izu-insularis is an evergreen terrestrial orchid of subtropical woodlands. In appearance the plant is nearly indistinguishable from related species, with each growth typically supporting two, sometimes three, heavily pleated, glaucous leaves, 15-35 cm long and 7-15 cm wide. These are born near to the ground and grow off a chain of underground pseudobulbs that are ribbed and rounded, giving the appearance of a shrimp’s body, hence the common Japanese name for the genus, ebine, or “shrimp root”. The roots are numerous, light brown in color, and mostly unbranched. In April the flower stalk arises from the center of the leaves to height of 30 to 60 cm, and can hold up to as many as 30 or more small purple and white flowers.

The flowers are typically not more that 4 cm across. The sepals and petals are pointed, splayed out star-like, and slightly recurved backward a the margins. Each is around 2 cm long and half again as wide. They are generally a light purple to lavender color with a hint of brown or orange suffused throughout. Lighter colored lines, appearing nearly white, commonly streak them as well. The lip and column are pure white, except for a small crest on the midrib on the upper lip that is lemon yellow. The lip has three lobes, two large lateral ones and a much smaller central one that is slightly bifurcated . They all point more or less downward. Each flower is graced also with a distinctive spur or nectary, that is often perfectly straight and stretches back toward the flower stalk, typically extending just beyond it.

Calanthe izu-insularis spur
The nectary or spur of Calanthe izu-insularis is long and basically straight in most specimens.

Its Japanese name is nioiebine, literally meaning “fragrant shrimp root” since the flowers give off an amazing floral scent that can be detected from a long distance away. In the Kanto region they are very popular and entire orchid shows are dedicated to them, not for their flower shape or color, but rather the quality of their scent. I would say they have a floral scent as opposed to a sweeter scent, as is common with other native Japanese Calanthe. Each plant has subtle differences in odor, not just in the strength, but also in the quality.

This species is found exclusively in the evergreen broad leaf forests of just three islands, all in the northern part of the Izu chain – Koozujima, Mikurajima, and Niijima. For this reason, this species has always been a rarity. Consider that the area in question is just a bit larger than Manhattan Island, totaling only 63 square kilometers (compared to Manhattan’s 59.5 square kilometers). While these islands yet contain plenty of habitat, over collection in past years has all but wiped them out from the wild. Currently they are listed as endangered status by the Japanese government, but in truth you’d be lucky indeed to see one growing in its native home anymore. For the very same reason, the natural hybrid between this species and C. discolor, C. Koozu, is a near ghost on the islands today as well.

Calanthe Kozu
Calanthe Koozu is the natural hybrid of C. izu-insularis and C. discolor. This clone has the typical color pattern for the hybrid, but its flower is much larger than most than since it is an artificially bred triploid.

Calanthe Koozu, is obviously named after the island it was first found. C. discolor is a widespread and common species found throughout most of Japan, Korea and parts of China. The flower of C. Koozu generally has more rounded and wider flower parts than C. izu-insularis, and the sepal and petal color tends to be a more rich, pure purple shade. The lip as well tends to be broader, reminiscent of C. discolor. In many specimens the lip is white, but often has more yellow on its crest and sometimes purple as well. The spur tends to be shorter than in C. izu-insularis and often has a curve to it. Having said all that, variation in color and form can be quite different from plant to plant, possibly due to back crossing and also because of the variability of C. discolor. So, flowers can have thin or wide segments, bicolored flowers to pure white ones, or ones fully suffused with purple, and so on. The flower’s fragrance can be floral, or in some cases have a much more sweet component. It is a real mixed bag – peruse the photos to see this great variation.

A note about naming. C. Koozu was originally found in nature, but has also been artificially produced since the 90s. The grex name Kozu was registered with the Royal Botanical Gardens at Kew in 1996 by K. Karasawa as an artificially produced plant. For this reason, I am keeping the capital “K” intact while in truth the original plants were found growing naturally making me want to call them C. x koozu. Also notice the double “o” I’m using – it is due to the Japanese name which has a drawn out long “o” sound, not a short one, and can be seen when read in kana characters. Romanization of Japanese characters is problematic and when blended with western phonetics and naming systems…let’s just say it becomes a mess. While binomial Latin names are accepted in Japan, they are rarely used by horticulturalists, hence they experience no problem with spelling issues.

Due to the rarity of C. izu-insularis it is a valuable plant in Japan, and to my knowledge is essentially unknown in collections outside the country. Add to this the fact that it is possible that some plants being called C. izu-insularis may not be full blooded, and so it is likely pure plants are very rare nowadays. Single young seedlings can fetch handsome prices, and adult plants, especially very select clones, might literally break the bank. By contrast C. Koozu is commonly grown and available in Japan, and indeed can be found in the US and Europe these days, largely due to a few dealers who have been willing to export to the international market.

Calanthe Kozu flower variation
Calanthe Koozu flower color and form is highly variable. Here are a few examples. The flower in the middle is typical, whereas the one on the left is more like C. discolor, and the one on the right more like C. izu-insularis.

As with all things Japanese, hybridization and the naming of the resulting plants is quite complicated with C. izu-insularis. Calanthe in general produce an amazing variety of forms and colors when hybridized. In nature many Calanthe species could be found growing sympatric (in the same habitat) such that it was common 50 or 60 years ago to see plants growing side by side with a vast array of colors and forms. These hybrid swarms were common on the islands of Kyushu and Shikoku, and in fact lead to the ebine craze that hit the country in the 1970s and 1980s. That craze was supported by the collection of wild plants, with select clones carrying near insane prices. To make a long story short, a viral epidemic hit the hobby hard, and by the mid 80s the entire thing seemed to be on the very threshold of collapse. Ironically, wild populations were so devastated by this collecting spree that most species have become threatened in the wild, and most remain so to this day.

Calanthe Kozu Shuuhakko
Some forms of Calanthe Koozu are mostly white like this one, or are bicolored white and yellow, or are completely yellow. This form is called ‘Shuuhakko’.

Then in the mid 80s a few pioneering growers were experimenting with methods for seed propagation in the lab, very nearly at the 11th hour. It was found that lab grown seedlings don’t carry the virus and suddenly new life was breathed back into the hobby, but it never has reached the fevered pitch it had back in the glory days. With controlled artificial hybridization the quality and quantity of ebine increased rapidly. In more recent times hybridization has become very complex, much like in Paphiopedilum or Dendrobium hybrids, making clear classifications difficult. See the chart at the end this article showing the classification scheme for C. izu-insularis. Remember, these are the basic hybrid types and as the years pass, the lines separating particular types becomes more and more hazy. The naming of various Japanese Calanthe hybrid types is an article in and of itself and really needs to be treated separately – I’ll do it one day!

A quick note about growing Japanese Calanthe. These are heat tolerant plants that require a chilling period in winter to grow and flower correctly. Indeed, the Izu Islands are essentially subtropical, but don’t think they are like Florida – winters there are pronounced enough to induce a dormancy from November through most of March. C. izu-insularis and its hybrids can be grown comfortably in USDA cold hardiness zones 7 and 8 without special protective measures, and where winters are overall cool (say the Pacific coastal states in the US or parts of the UK) zone 9 is acceptable too. Regions with colder winters will require heavy mulch, but unless summers are sufficiently warm and humid, these plants are unlikely to thrive.

Calanthe Kibananioi
C. izu-insularis has been hybridized with a wide range of other Japanese Calanthe. One hybrid type is called Kibananioi, created by crossing C. izu-insularis with C. sieboldii.

Having said that, evergreen Calanthe in general are best grown in pots, not in the open garden. One reason is that virus transmission in the ground can lead to wholesale loss of a collection whereas suspect plants grown in pots can be simply thrown away in the domestic trash (pot, compost, plant, and all!). Virus infected plants often have light colored streaking in the leaves, and the flowers can be blotched and malformed. Indeed, less serious infections and bug infestations can cause alarming symptoms as well, and the differences need to be learned by serious grows of these plants. If I find a plant that is suspect, without deliberating, I throw it away – the risk of viral contaminants infecting other plants is just too high.

The compost should be coarse in structure with a high level of organic materials. I use a mix of coarse pumice (diameter size around 2 cm), coir, and fine grade orchid bark. Keep the plants moist at all times. In summer they should be fertilized on a regular basis starting after flowering and particularly at the end of the growing season – September and October here – so that they can produce large, flowering size buds for the following spring. These protrude out of the medium a bit and are green in color.

Calanthe izu-insularis hybrids
The hybrids of Calanthe izu-insularis are of seven basic types as seen in this chart. Abbreviations as follows: IZU (C. izu-insularis), DIS (C. discolor), SIB (C. sieboldii), and ARIS (C. aristulifera). The designations in parentheses are other Calanthe hybrid types, for example DIS x SIB = Takane, the natural hybrid between C. discolor and C. sieboldii.

When temperatures rise in late March or April they will begin rapid growth and flower within a few weeks. The leaves can last up to three seasons, but I usually prune off old leaves after two years since they tend to accumulate rot spots – another problem with growing these plants. In summer water daily in times of high heat and try to keep your plants in humid conditions. These are forest dwellers in the wild, so grow them like a fern, not a cactus.

Lovely and precious, C. izu-insularis and its hybrids beckon the serious terrestrial orchid grower – but watch out, they can also empty your wallet!


8 Replies to “Endangered Calanthe orchids from the Izu Islands, C. izu-insularis and its hybrids”

  1. Botanyboy i enjoy your info about Japanese plants….

    I am a hostabreeder…no nusery…bu privat garden owner.
    John Hostavalley is my name on the internet.

    Please some info about Japanese hostas would be great to. Keep up the good work.

    1. In terms of hybridization I think breeders in Europe and America are way ahead of those in Japan. I do occasionally see the native H. sieboldiana in the wild here. I’ve seen hostas in some pretty unexpected places, for instance growing up in trees, on vertical cliffs and even in upland peat bogs in full sun. BTW, you have one heck of a collection. I’ll keep an eye out for hostas more in the future but I’m afraid they could hold a candle to your lovely plants!

    1. Yes, I love both Cypripediums and Calanthe too. I can grow Calanthe here, but it is just too warm to grow Cyps reliably. BTW, I was thinking of you this week since I just saw hundreds of Hosta sieboldiana growing in habitat on a dripping wet cliff-side in the mountains near my house. If you look at my most recent video titled “Walking podcast, Botany Boy Hiking in Japan” you’ll see some of them near the end of the vid.

      1. Tom…i have watched your video with the Hostaseedlings on the rockwall. Amazing spot. I love those nature pictures. Are you sure the where Hosta sieboldiana seedlings?. I couldn’t look at them close….you did. Most are Hosta Longipes that are found on those rocks.

        Thanks allot for the videos…i keep a big fan of it. I hope to come in the near future to this great Country….in the footsteps of Von Siebold. I am reading some books now of his history in Japan. A amazing life.

        1. Yes, I think you are correct. H. sieboldiana in fact doesn’t appear to be native to my area at all! The plants native to Kyushu that commonly grow on rocks and trees are in fact Hosta longipes var. caduca. Ah well, so much for doing my research… but I just spoke the name I knew out in the field. I’ve seen Hosta growing on rocks, trees and in wet, boggy places here. I’ll have to research more about the species native to Kyushu. So many plants, so little time!

Leave a Reply

Your email address will not be published. Required fields are marked *