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.

Western Coralroot (Corallorhiza mertensiana)

The Western Coralroot is certainly aptly named since it is found only in the far west of the United States and Canada, primarily along the Pacific coast from Alaska to California and east only as far as Montana and Wyoming.

In our experience this is the most widespread of all the Coralroots, growing from sea level to much higher elevations and often found in profusion where it is growing.  We have seen it by the thousands in several locations.

It generally grows in rather dark forests where little else is growing on the forest floor and amid a litter of dead branches and decaying trunks.  Like all Coralroots it is leafless and saprophytic or more accurately, mycotrophic, depending on a fungus for its nourishment.

The usual color form has purplish stems and flowers that are bird-like in form.  The stems are generally about 45 cm tall and carry up to 35 flowers.  The lips vary from a solid purple to a purple and white that appears to be striped.

There are two named color forms, forma albolabia, which has no purple color at all, and forma pallida, which has very pale pink stems but retains some of the purple color.  This latter color form is quite common, but stands out on the forest floor even more dramatically than the normally colored form.

C. mertensiana fma. albolabia

C. mertensiana fma. pallida (below also)

In fact there are found so many color variations, that with the exception of the albolabia form, none of them really deserves to be called a form.  The stems vary from a very dark reddish purple to pale lavender, from off white to tan to a yellowish color.  The lips vary from nearly solid red-purple to lips that have varying amounts of white, and from striped to spotted.  The tepals from pale yellowish white through lavender and tan to a very deep red-purple and all of these in every possible combination.