Friday, September 21, 2012

Color Forms of the Western Coralroot

The Western Coralroot, Corallorhiza mertensiana, is aptly named since it cannot be found east of the Rockies either in the United States or in Canada.  In the west it is quite common and when found is often growing in large numbers.  It can be found on very dark forest floors where nothing else is growing and then especially in the paler color forms stands out vividly.

We have seen this species in many different locations and in many different color forms, the different color forms often growing among each other and apparently hybridizing with one another, with every possible color combination and shade to be seen.  These different color forms, which make the species so interesting are the subject of this blog post.

There is a form of the this species is a deep and rich reddish purple color, with stem, flowers and lip nearly uniform in color, only the light yellow tip of the column and some paler markings on the lip interrupting the uniformity of color.  This variety, when we have found it, seems to grow without any other color forms, and is perhaps worthy of being considered a named form.

This appears closest to the ordinary form, described by Paul Martin Brown as having reddish-purple stems, bronzy-purplish tepals (sepals and petals) and a bright purple lip.  We have found flowers more or less matching this description but they are no more common than any other color in the areas we've searched, and even with them there is considerable variation of color.

There are two named forms, forma albolabia, a form without any purple coloration at all.  We have seen this once, on the Thunder Creek Trail in the North Cascades.  Its pale yellow color and white lip are very striking, but it is also the rarest of the different forms, at least in our experience.  In our opinion this is a legitimate named form and is very distinctive.

The other named form is forma pallida which Paul Martin Brown describes as having stems and flowers of palest lavender with a bright purple lip.  While we have seen many paler colored plants there are few that exactly match this description and much variation of flower, stem and lip color even among those paler forms.  We have some doubt that this is a legitimate named form.

When we've found different color forms growing together there is endless variation, though we never found the dark purple form in such locations.  In these areas the stem color ranges  from a deep reddish purple to dark pink and dark tan.  The stems of the lighter forms range from off-white, to pale yellow, pale lavender and tan.

Lip color ranges from nearly uniform dark pink and purple, to lips that are more white than colored with purple or dark pink edges and marks.  We've found purple or dark pink lips with a white splotch on the end, white with purple edges and a dark pink splotch in the middle, white with purple spots, and dark pink with darker purple markings.

The color of the tepals in these intermediate  forms ranges from the bronzy-purple described above, to lavender, tan, pink and pale yellow, some without spotting on the sepals and some with more or less spotting.  And combined with the lip these are found in every possible combination, making it rather fun to examine them and photograph them.


  1. wonderful photo essay of all the different forms. I think I fvor the last form with the palid stem and the vibrant flower

    striking photography given the usual dark environment.

    I look forward, as always , to next spring so the adventure of discovery can start over.

    1. Thanks for the comments, Marti. I am intrigued by these and the variation in them. Photographing them is always a challenge, though. The last time we photographed them on Hoypus Hill it was quite dark and there was the slightest of breezes as well.

  2. WOW!
    Yet anoher high quality post. If I ever make it back to the pacific northwest, I so would love to see those.

    We only have Corallorhiza trifida here. And it is the only species of this genus I have seen thus far. A very inriguing genus.

    Thanks for sharing!

    1. Hi Martin,
      We have five species of Coralroots here in Washington, including C. trifida, but there are many different varieties, forms, and a lot of color variation with some of them. Most of the species are relatively common, but one is rare, here in the west.

      If you are ever out this way it would be a delight to show you around. The season is fairly long, too, since they bloom at different times at different elevations.

    2. Hi Ron,
      I hope to be able to return to the pacific northwest one day. We had the most memorable time in the northwest and also in the Rockies. Next time is still a few years away tho. So much to see, so little time.

      If you ever make it to Germany tho, I'd be happy to also show you places. Lots of old stuff, but also flowers (like for example Liparis loeselii). ;-)

    3. So much to see and so little time is so true! All the years we've lived here and we still haven't seen everything we'd like to see. Already thinking about next summer and the places we want to hike.

      Would love to see some of the European natives. Saw a few in Northern Ireland when we lived there and some in the Burren in County Clare, but that's all. Maybe someday.

    4. I still have not even seen all areas in Germany. So a few native orchid species are still missing from my list. I know quite a few good spots in the southern and western parts tho.

      The Burren is also excellent for orchids. We have seen about 10 species (not sure how many exactly) in a day and seen them in abundance too, when we visited in 2009. I love Ireland (if only the weather was better in the northern parts ;-)).

      Next summer we plan to do a trip to Scandinavia (hopefully seeing Calypso bulbosa and wolverines).

    5. We have by no means seen all the areas of our state, either, and there are several species that we will be looking for next summer. We have a location now for Cypripedium parviflorum and one for Spiranthes diluvialis, a rare natural hybrid. Then there's one Coralroot we haven't found and one Listera as well, though we have a location for the Listera. Calypso bulbosa is everywhere here in the spring, but only the western form

  3. I'm on the hunt for C. striata in Mount Rainier National Park. I have a reliable report of it, but it's interesting to note that the herbarium specimen referred to as C. striata turned out to be C. mertensiana instead.

    1. Interesting about the herbarium specimen. Melissa has been trying to sort out some of the errors at the UW herbarium though more recently she is very busy. I've not heard of striata in the park, but would be interested in knowing if you do find it.