Story behind the art of Erika Hargesheimer
Curious Allies: Mutualism in Fungi, Parasites, and Carnivores
The Fifth New York Botanical Garden Triennial
Striped Coralroot Orchid
Corallorhiza striata
Corallorhiza striata (C. striata), commonly known as the striped coralroot orchid, is found in undisturbed woodlands in Canada from British Columbia to Quebec and in the USA from California to New York. Have you ever seen one? Even though it is rare and can be elusive, it is definitely worth the extra effort it might take to find it. This wildflower is a great example of a “Curious Ally” because it relies on a fascinating network of fungal hyphae (fine, stringy fungus filaments) and tree roots to provide it with all of its needs: food (sugars), minerals (like phosphorus, nitrogen and potassium) and water. Without this network, C. striata seeds could not even germinate and the plant could not grow and thrive.
I am a wildflower enthusiast and for many years have been drawing, studying and photographing wildflowers while hiking in the national and provincial parks near my home in Calgary, Canada. My favorite wildflower is the striped coralroot orchid. I think adjectives like beautiful, wild, distinctive, and down-right quirky best describe this spectacular plant. It really stands out when it blooms in the spring because the reddish-purple coloration of the whole plant (stems and flowers) contrasts with the bright green of its natural habitat. Imagine hiking in late May to early June on a sunny, “blue-sky day” in your favorite wilderness area and suddenly coming across a large patch of C. striata – erect, stout reddish-purple stems 7-18 inches tall, each holding 7-28 striped reddish-purple flowers about 0.5-0.8 inches across. The dark central lip is framed by three sepals and two lateral petals, each arrayed with conspicuous purplish stripes. At the centre of each flower, a bright yellow dot catches your eye. Wow - this burst of color acts like a beacon for people and pollinators alike. C. striata flowers are the largest of the coralroot orchid flowers, but they are still relatively small compared to many other wildflowers. It is not the flower size that demands our attention. It is the sheer number of flowers (hundreds of flowers in a large colony) and the bright reddish-purple colors that make this plant sensational.
Did you know that there are over 28,000 species of orchids in the world? In nature, all orchid seeds rely on fungi to sprout. The beautiful flowers of C. striata, for example, attract pollinators like mosquitoes, small wasps, and gnats, producing millions of dust-sized seeds. Its seeds do not carry enough food to germinate by themselves. They must immediately connect to fungi in the soil that provide the tiny seeds with food and water. After they germinate, most orchids develop green leaves, make their own food by photosynthesis, and bring in nutrients and water through their own root systems. Only about a hundred orchid species*, including Corallorhiza, never develop green leaves to make their own food and do not have roots. It almost sounds like a curious riddle: “What plant has no leaves but has flowers?” and “What plant has no roots but gets food and water from the soil?” Answer: Corallorhiza striata!
All coralroot orchids (10 different species in North America) have rhizomes. A book titled “Native Orchids of Minnesota” includes a good photograph of a C. striata rhizome**. It looks like a piece of coral, about three inches long: black, stout, compact, and branched. Other well-known plants that have rhizomes are bearded iris, canna lily, and ginger. Rhizomes are more like underground stems - they grow by a series of nodes and internodes. Most green plants with rhizomes also grow roots attached to the rhizomes. So, they can make their own food through photosynthesis and then bring water and nutrients back to the rhizome through their roots. They are self-sufficient. Rather than having roots, all coralroot orchids are mycotrophic (from the Greek words “mykes” meaning “fungus” and “trophe” meaning “nourishment”). Coralroot orchids transport food, minerals and water from tree roots through “mycorrhizae” (from the Greek words “mykes” meaning “fungus” and “rhizoma” meaning root-like) into their black coral-shaped rhizomes. (The black rhizome color comes from C. striata’s preferred fungus partner: Tomentella fuscocinerea*.) Interestingly, C. striata associates almost exclusively with this single species of Tomentella fungi, but has a relatively broad range of possible tree hosts. Many different coniferous (pine, cedar, spruce), deciduous (ash, birch, poplar, aspen, maple) and mixed-wood forests support the mycorrhizae connected to the C. striata rhizomes**.
In 1990, Dr. Suzanne Simard*** first coined the phrase “Wood-Wide Web” to describe the connections she discovered between soil fungi and plant roots. She found that fungal networks connect most land plants together, allowing them to communicate and bringing great benefits to all members of the network. In contrast to the man-made World Wide Web, which was invented in the late 1980s, the “Wood-Wide Web” has been making beneficial connections between plants and fungi for over 400 million years!
Mycorrhizae are made up of fungal hyphae and tree roots but are something distinctly different from either of these two individual component parts. The mycorrhizae are an ingenious combination of tree roots and fungal hyphae that bring mutual benefit to both of the partners. The tree and the fungus both get more food, nutrients, and water through the mycorrhizae than they could get for themselves. C. striata then connects into this highly beneficial two-way relationship. So, the question becomes: does Corallorhiza striata actually contribute some benefit to the tree and fungus partners? Or is C. striata just “a pretty face” taking advantage of an abundance of free food and water? C. striata may be just a lucky free-loader but one day, scientists might discover that coralroot orchids do benefit the mycorrhizae in some way. From a human perspective, there is no question that Corallorhiza striata contributes tremendous beauty to our world.
I suspect that one of the biggest threats to the survival of C. striata comes from well-meaning admirers who cannot resist using a shovel instead of just a camera to “capture” this lovely orchid. Trying to take a piece of striped coralroot home from a protected natural area is, of course, illegal but it is also always fatal for C. striata because this leafless orchid cannot survive without the complex linkages that exist between its rhizomes and the fungi/trees that nurture it. C. striata is not endangered in most of its range but the growing conditions provided by its extraordinary fungal network can never be replicated in a garden. It is important to admire plants like C. striata where you find them but always leave them growing in their natural habitat.
My watercolor painting depicts a large patch of C. striata with fourteen delicate growths holding more than 100 flowers and 75 buds in various stages of development. There are just a few wispy blades of green grass depicted at the base of the striped coralroot to anchor the main subject and suggest a habitat context. Of course, the C. striata plant itself contains no green whatsoever. The brilliant red-purple found in C. striata automatically brings my watercolor palette to mind: perylene maroon, quinacridone magenta and purple madder. As the shoots come up out of the ground, pale sheaths clasp the brightly colored stems near the bottom, but there are no green leaves. People viewing the painting will immediately notice that neither the mycorrhizae (fungus and tree root network) nor the rhizomes (from which C. striata flower stems sprout) are depicted. These structures are buried very deeply (more than eight inches*) so there is a real danger that the plant could be destroyed by any attempt to uncover them. Since I have only seen one photograph of the black coral-shaped rhizome in Smith et al.** and found no sources to study the mycorrhizae, I was not able to depict these two important features in my composition.
Over the years, I have discovered some wonderful spots to observe the striped coralroot orchid. There is one special place on the eastern slopes of the Rocky Mountains that I visit almost every year in mid-June to admire a stunning patch of C. striata. For me, it has become almost an annual pilgrimage. Now that I know what I am looking for and when to go, I have also found C. striata growing in municipal parks and natural areas right in the city of Calgary. “The more you look, the more you see”, as the old adage goes! Corallorhiza striata is truly a wild and untamed treasure that cannot be captured, cultivated, or owned. I hope that viewers will admire the beautiful above ground features depicted in the painting and imagine the “mycotrophic magic” happening below ground.
*Siegel, Carol. 2015. “The Secret Life of Orchid Roots,” Orchid Digest. Jan, Feb, Mar. 2015.
**Smith, Welby R., Vera Ming Wong and Bobbi Angell. 2012. Native Orchids of Minnesota. New Edition. University of Minnesota Press. 288 pp.
***Simard, Suzanne. 1990. “The Wood-wide Web: how trees talk to each other. Available online at: https://www.okido.com/blog/steam/the-wood-wide-web/. Accessed February 2024.
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