The Siskiyou Wild Rivers area in southwestern Oregon is one of the few regions in the lower 48 with such extraordinary biodiversity. This week's featured wildflower is a three party, symbiotic relationship, between the orchid, a fungus and an old growth Douglas fir tree.

Purple Coralroot, Corallorhiza mertensiana

Flourishing in the old growth forest of the Pacific Northwest there is a lot that can be said about the Purple Coralroot, Corallorhiza mertensiana--starting with the fact that a few individuals (like the one pictured to the right) can be entirely yellow rather than purple.  Purple coralroot is an orchid that supports a number of small flowers along its single, translucent stem.  One of four species in the Pacific Northwest, coralroots in general tend to grow in dark, shaded forests that lack other flowering plants in the understory. Sometimes hundreds, if not thousands of individual Purple Coralroots can be seen dispersed over a few acres under old growth Douglas fir.

As a non-green plant one can rightfully assume that this orchid must obtain its energy from some source other than directly from the sun.  Although the plants have retained reduced, vestigial leaves, only the flowers ovaries, that are green, carry out an inconsequential amount of photosynthesis. Instead, purple coral root, which technically lacks roots, has short, knobby rhizomes that look a bit like marine coral, but are enveloped in soft fungus tissue in what is termed a “mycorrhizal relationship”. Hormones from the fungus the orchid is associated with actually suppress root hair growth in the orchid, which instead directly inhabits its cells, and also penetrate the root hairs of certain coniferous trees.

The latest evidence shows that the fungi associated with coralroots are not simply gathering nutrients from surrounding organic matter and then giving it to the orchids.  The orchids are more like parasites of these fungi, both of which are symbiotic with the surrounding trees. The carbon containing sugar molecules that provide energy for both the fungus and the orchids come from the association the fungus has with the roots of its host trees. The trees are benefited from the increased absorption of water and mineral nutrients due to the greater absorptive qualities of the masses of fungal hairs (hyphae) that have penetrated and formed a net-like growth in between the cells of the tree roots as well. But the orchid and fungus are equally dependent on the trees, which is the only organism in the triad capable of carrying out photosynthesis.

Were all this not strange enough, as with many other orchid species, the dust-like, tiny seeds of the coralroot orchid cannot germinate unless they are first penetrated by the microscopic thread-like hypae of their associated fungus species.

Corallrhizae, literally means coral root, and mertensiana is for a German botany professor Franz Karl Mertens (1764-1831).