A beautiful orchid “weed”, Spiranthes sinensis

Japan has one truly weedy orchid species, Spiranthes sinensis.  This is a remarkable plant for many reasons, not the least of which is its startling purple-pink color.  It is one of the few orchid species that has actually benefited from human activity, in particular the clearing of forests and creation of grassy areas where it thrives.  Let’s take a closer look at this fascinating plant.

Spiranthes sinensis habitat
Spiranthes sinensis is commonly seen on roadsides, fields, and lawns. These are growing in a park in Sasaguri Town, Fukuoka Prefecture, Kyushu.

Spiranthes sinensis is a short-lived perennial plant, growing singly or in small clumps, and capable of forming colonies of thousands of individuals.  In mid fall a small rosette of bright green leaves form around a central growing point. They are held close to the ground and are 3-6 cm long and 1-1.5 cm wide.  In the cold winter months they stop growing but remain green.  Starting in late March they begin to grow again and by May or June have elongated up to 12 cm and increased in number.

Sometime in late June the branch less flower spike begins to grow from the central growing point and by mid July is standing 15-40 cm tall and sporting anywhere from a handful of flowers to several dozen.  The flowers are arranged in a helix around the spike, and flower sequentially.  The flowers are small, no more than 6 mm across.  The sepals and petals are long and point forward with the dorsal sepal and two petals forming a little hood over the lip.  They range from pale pink to deep lavender in color.  The lip is relatively broad and tongue-like in shape and recurves downward.  It is frilled and pure white.  The overall look of the tiny flowers is crystalline.  Albino forms exist, but why would you want to have just another white Spiranthes?

Spiranthes sinensis as a well
Volunteer seedlings show up all over the garden. In this case a seedling is growing in an epiphytic cactus pot.

Seed formation is rapid, probably taking just a few weeks.  By the time of flowering the leaves are all but spent, and after flowering they disappear completely only to regrow a few months later.

These lovely plants range over all of Japan, the Korean Peninsula, part of Russia, and also China.  They favor open, sunny, grassy areas such as roadsides, fields, the berms of rice patties, and lawns, but also grow in bright shade just within the eves of a forest.  It is a common volunteer plant in garden beds and flower pots as long as these are sunny and moist.

One thing I like about Japanese orchids is that they aren’t gaudy or overstated, but rather tend to be small, simple, and elegant.  This plant is a good example.  If you are zooming down a highway you will miss this plant in flower even though thousands many be growing on the very edge of the road.  To truly enjoy it you have to get down on your hands and knees (I prefer my belly) and take a close look.  You’ll be amazed with what you see:  spirals of pristine purple-pink and pure white crystalline flowers bathed in bed of grass.

Spiranthes sinensis flowers
Up close the flowers of Spiranthes sinensis are truly spectacular.

Anyone familiar with the North American members of this genus will be surprised with the flower’s color since virtually all other species are either pure white or yellowish.  I’m constantly on the lookout for this little plant when I’m near a grassy park or field. In Japan grass is not usually cut at regular intervals as in America, but is left to grow for a month or more giving the Spiranthes plants time to grow, flower, and even set seed.  They set seed remarkably fast – possibly as fast as just a few weeks.

S. sinensis flowers
Spiranthes sinensis flowers are highly variable in color. These show the pale end and the dark end.

I’ve seen them growing in just about any conceivable place as long as there’s sun and moisture in abundance.  This terrestrial orchid benefits from the works of people unlike almost all of its kin, and probably grows in greater numbers now than in years before humans settled these islands.  Given their ability to live alongside humans, this species has a secure future.

This is not a long lived plant, with each individual probably lasting no more than 4 or 5 years.  They grow readily from seed even without the benefit of the sterile conditions of a flask.  In other words, plant one and more will come!

In cultivation the plants will show new growth in late summer after flowering.  In habitat they tend to go semi-dormant until mid fall when they’ll send up a few new leaves, forming a compact rosette.  These will persist all winter until the warm weather comes at which point they grow fast culminating in flowering by mid July.

Spiranthese sinensis seed pods
This plant sets seed on most flowers, one of the reasons it is such a successful species.

Because of this growth cycle, I keep mine in bright conditions year round, but only fertilize them when in active growth. They will grow in any well draining compost, but I’ve even seen a few come up in my bog gardens.  They seem to prefer good drainage, but constant moisture as well.

Given the range of this species, it seems indifferent to temperature, though I’m sure that local variants exist, so not all plants will have equal cold hardiness.  In nature they are found from USDA cold hardiness zones 3-11, the equivalent of south Florida to Labrador!  So, sourcing the right plants for your conditions is probably important.

See this species growing naturally in Japan in this video:

A dainty little plant and worth growing. This is one weed you won’t mind growing in your garden.

Spiranthes sinensis plant
Throughout the winter the rosette of leaves remains green. Only during blooming does it wane.
Spiranthes sinensis flowering plants
Spiranthes sinensis is one of the prettiest weeds!


3 Replies to “A beautiful orchid “weed”, Spiranthes sinensis”

  1. Spiranthes sinensis has an incredible distribution from China south to western Australia and New Zealand. The next time you have the opportunity would you please go to your populations of S. sinensis in Japan and count the number of white forms to pink-purple forms? The white form appears to be common in parts of China but it appears to be very rare through eastern Australia.

  2. Actually in Australia the name Spiranthes sinensis has misapplied to Spiranthes australis (R.Br.) Lindl.
    Ross, J.H. & Walsh, N.G., (2003) A Census of the Vascular Plants of Victoria. Edn. 7: 27

    misapplied to: Spiranthes australis (R.Br.) Lindl. by Ames, O., (1908) Orchidaceae. 2: 53 apni

    Barker, W.R., Barker, R.M., Jessop, J. & Vonow, H., (2005) Census of South Australian Vascular Plants 5th Edition. Journal of the Adelaide Botanic Gardens Supplement. 1: 201

    misapplied to: Spiranthes australis (R.Br.) Lindl. by Ames, O., (1908) Orchidaceae. 2: 53 apni

    1. Ah, I leave naming to the botanists – many of whom do not agree with each other! The last I looked on Kew’s site, they were still calling S. australis a synonym of S. sinensis. Without a doubt, if they are indeed distinct, they are very closely related. Thanks for the input though – I really do appreciate it. Tom

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