The Reappearance of the Crested Coral Root Orchid: A Tale of the Orchid and the Vine

The research of noted orchid scholar Stephen R. Hill at the University of Illinois at Champagne-Urbana would suggest that we have a gem that in 2008 may have approached a national record. The population of Crested Coral Root Orchid that grows near Ward's Mill in Louisville's Cherokee Park was one of the largest of its kind in 2006-2008. Dr. Hill teaches in the university's Division of Biodiversity and Ecological Entymology. A population in Oklahoma is believed to have outnumbered the potentially 100-150+ plants seen in Cherokee Park in 2008-2010, numbering several hundred in a blackjack/post oak community. No other populations approach these two, within the research of Dr. Hill.

A photo collage on Flickr would suggest that the orchid occurs at a similar density, but fewer numbers, numbering more than dozens of plants at the Atlanta, Georgia Botanical Gardens. According to Dr. Hill and other botanists consulted for his Conservation assessment, it is rare for the orchid to occur in populations larger than a dozen flowers in any locality it occurs. 

Crested coral root (Hexalectris spicata), is a saprophytic orchid; meaning, it lives in symbiosis with the roots of the trees which occur in "Glen Lily" as the area is known by the Olmsted Parks Conservancy. This fungal relationship feeds off the nutrient sharing fungal network known as mycotrophic, or ectomychorrhizal fungi. 

The orchid may disappear underground for periods of up to ten years, and it is not known how to propagate it. A flower resembling purple asparagus with notes of brown and pink, first rises from ground during the end of June, once warm weather rises to sweltering conditions leading into the 4th of July. Crested coral root blooms until at least the last week of August, with 2013 being an unusually cool summer, finally warming up into the mid 90s by the last week. 

When open, the orchid has softly painted brushstrokes of purple upon a yellow lower. Spiderwebs are seen on the orchids, but the flowers are not believed to be pollinated. What we see above ground in the individual flower stems are our only clue as to the presence of this unusual orchid.

The white tailed deer living in Cherokee Park are believed to browse on the orchids, although chipmunks, squirrels, raccoons or opossums may also dine upon the orchids. 

What the orchid likes is clear. It loves thin, rich soil, limestone, open woods and glades. In Cherokee Park, it appears to be associated with Shumard oak (Quercus shumardii), black oak (Quercus velutina), chestnut oak (Quercus montana), chinquapin oak (Quercus muhlenbergii), blue ashes (Fraxinus quadrangulata), green ashes (Fraxinus pensylvanica) American elm (Ulmus americana), American beech (Fagus grandifolia), hackberry (Celtis occidentalis), white oak (Quercus alba), shagbark hickory (Carya laciniata), Ohio buckeye (Aesculus glabra), Pawpaw (Asimina triloba), blackhaw Viburnum (Viburnum prunifolium), Sugar maple (Acer saccharum), Eastern red cedar (Juniperus virginiana), redbud (Cercis canadensis) and bladdernut (Staphylea trifoliata). This would be known as a subxeric hardwood forest. The soil is well drained due to its slope with rich black topsoil occuring over heavy clay.

After a careful study of the other locations nationwide the crested coral root occurs, the following plants all are potential associates for this orchid. 

While in 2008,  a non-native "invasive" ground cover called "five leaved Akebia" or "chocolate vine" (Akebia quinata) blanketed the ground in this patch of open woods, the crested coral root existed in numbers as high as 100-150+ plants (Patricia D. Haragan).

The vine is called chocolate vine for its reportedly delicious fruit, which has only occurred once in the observation of Haragan, once Olmsted Parks Conservancy's staff botanist, publishing a flora this fall of the plants of the Olmsted Parks of Louisville, Kentucky.

So in 2008, the record setting year of the Coral Root, the ground cover was less than 1 foot deep soil and broken limestone from a Dolomitic cliff that straddles the boundary of the Presbyterian Theological Seminary. I would postulate that the ground cover may have provided the following benefits to the orchid: it maintained disturbance, by strangling any young saplings that threatened the openness of the forest floor. It therefore prevented the shrub layer from invading the open conditions the orchid seems to prefer. But don't think of it as sunlight competition. 

The orchid mainly lives underground. So it is mainly a matter for soil science to sort out. The chemistry of the fungal and bacterial colonies that live in the soil, coupled with the characteristics of the above ground trees, shrubs, grasses, and forbs (wildflowers) produces this orchid. It grows in association with the other plants, an ecologist would say.

The native grasses of this area are limited to bottlebrush rye (Elymus hystrix), while the forbs consist of tall American bellflower (Campanulastrum americanum), tall upland boneset (Eupatorium serotinum), and three lobed black eyed Susan (Rudbeckia triloba). A small amount of false Solomon's Seal occurs in this area as well (Maianthemum racemosum) and Virginia creeper (Parthenocissus quinquefolius).

Besides Five Leaved Akebia, the other "invasive species" are garlic mustard (Alliaria petiolata), winter creeper (Euonymus fortuneii) - only one orchid has ever been seen growing from the winter creeper, and Tree of Heaven (Ailanthus altissima), which grows on the cliffs above the orchid, but has probably not invaded the soil occupied by Hexalectris spicata.

As the exotic Akebia vine has been controlled by foliar applications of glyphosate herbicide, the warnings of Dr. Stephen R. Hill have come true. He warns in "Conservation Assessment for the Crested Coral Root Orchid (Hexalectris spicata (Walter) Burnhart)" that fungicides and herbicides should not be used over a population of the orchid. Fire, should be used in preference of the other two methods to manage pathogenic fungi, or invasive species, is the inference suggested by his research.

The orchid population has been diminishing each year since 2008 in size. In 2010 as many as 100+ orchids occurred (Wysor). It was also 2010 that the United States Coast Guard under the management of Joe Manning released another rare plant suppressed by bush honeysuckle: Eastern yampeh (Perideridia americana). 

This same stump treatment method with glyphosate not foliar sprayed but rather carefully painted on cut stumps has restored another rare plant in the same area: Eastern yampeh (Perideridia americana) a wild relative of the carrot which is exceedingly rare in Kentucky, listed in Mabel Slack's 1941 Cherokee Park flora, and was rediscovered in flower in April 2011 by Wysor.

Then in winter of 2013 another rediscovery of purple cliff brake (Pellaea atropurpurea) and blunt lobed cliff fern (Woodsia obtusa). These discoveries have confirmed to a greater degree what Pat Haragan's survey of Cherokee Park had initially suggested: the Glen Lily area has the greatest biodiversity and intact remnant plant communities of the entire Louisville Park system, with a few exceptions at Iroquois Park.

In fall 2011, the chocolate vine was sprayed, killing much of the ground cover where the orchid resided resulting in a loss of topsoil, and exposing the heavy clay subsoil (Wysor). The upper areas above the trail along the cliff were sprayed last, as part of several 8% foliar glyphosate applications resulting in a loss of a test control (Wysor).

However when in 2012, during summer, Olmsted Parks Conservancy Woodlands Restoration Crew removed Asian bush honeysuckle (Lonicera maackii) and Standish honeysuckle (Lonicera standishii) using a 25-50% concentrated stump treatment on chainsawed stumps, a new control plot emerged. On very sporadic centers, a light infestation of shrub cover now provided the control necessary to test herbicide application in proximity to the orchid. Due to the low density of the invasion, the amount of herbicide used was less than that used in the foliar applications to treat Akebia vine. It would seem the theory of David Fothergill, 2008 Olmsted Parks' Woodlands Restoration Manager, now with the US Forest Service may have been correct: stump treatments of higher concentration herbicide are less harmful to mychorrhizal associations than blanket foliar treatments at high concentrations.

What has occurred is that the population of the orchid has spread into the area previously occupied by the Asian bush honeysuckle, which is known to nitrify the soil, adding excess nitrogen, encourage invasive earthworms, and result in a quick breakdown of leaf litter according to Dr. Margaret Carreiro, Urban Ecology Professor of the University of Louisville, who has spoken on the phenomena on local television interviews spotlighting the environment. 

Since 2011's honeysuckle removal, where the population of the orchid has spread and has already started to build up a deposition of leaves, the humus is primarily oak leaves: black oak (Quercus velutina), chinquapin oak (Quercus muhlenbergii), red oak (Quercus rubra), Ohio buckeye (Aesculus glabra) blue ash (Fraxinus quadrangulata) and red elm (Ulmus rubra). It is not known how the death of the blue ashes and green ashes in this area will impact the growth of the orchid. But oaks are most important to this relationship, according to Hill.

Additionally, as Dutch Elm's Disease fungus has occurred in Louisville since the 1930s, it is not known to have an impact on the growth of the orchid. But when Mabel Slack wrote her flora in 1941, she does not list elms in her flora whatsoever. Whether this was an omission, or she declined to collect specimens for fear of spreading the fungus, we may never know. It is possible that even seedling elms had been deleted from Cherokee Park during the initial spread of the disease, though this is hard to fathom from their relative abundance in modern day times. 

The vine may also have provided moisture and shade from sunlight during periods of drought, by protecting the top of the slope's topsoil layer from rain, or sun during daylight hours to this south-facing slope. The vine's evergreen growth habit may have protected soil from winter freezing, and helped capture moisture from melting snows, ice. 

At the time of this publication, Sept. 1, 2013, the orchid has just gone underground for the growing season. Last Saturday, as I walked with a labor organizer with AFSCME, we counted less than a dozen still blooming. Troubleingly, there were never more than 35 orchids in bloom, and as few as 50-60 all year counting all the stems eaten, wilted, or trampled. 

The Akebia vine lay at heights of no more than one foot depth, climbing the undergrowth whenever it could, obtaining heights up to 30 feet, still visible in some of the American elms growing on Beargrass Creek across from a Native Cane planting at the design of Charles David Fothergill, Woodlands Restoration Manager in 2008, the year of the record. Noted Kentucky botanist and cane plantationist Julian Campbell helped guide the planting effort which simulated a design by Frederick Law Olmsted used along the entrance road of the Biltmore Estate, which Olmsted besides Cherokee Park was his final design.

From the vantage point of the edge of the orchid population to the East, where pawpaws grow, and produced fruit this year, one can see the restored Olmstedian cane plantation across Beargrass Creek, where water willows (Justicia americana) grow upon the shoals of the Creek at a rare location where the stream bank is still healthy, because it runs across a gigantic slab of Jeffersonville Limestone the surging sewers of Beargrass Creek have not been able to flush into the Ohio River, with its mugwort (Artemisia vulgaris), Japanese chaff flower (Achyranthes japonica), and wild bean (Phasoleus polystachios). 

Missing from this equation is the Short's goldenrod (Solidago shortii) not yet discovered at the time of McMurtrie's Florula Louisvillensis. Missing also is the big leaved scurf pea (Orbexilum stipulatum), now believed extinct, that may have grown on Beargrass Creek at this location. 

Also we do not have bobcats, bears, wolves, elk, or bison. 

How will the crested coral root orchid persist into the future of this biome? Only time will tell.