Garden Scientists Find an Endangered Arizona Orchid


Photos by Eirini Pajak

Orchids are a well-known to most people for their beauty. They grow on every continent except Antarctica, and the blooms of these plants come in almost every shade of color. In North America, there are more than 200 orchid species, and more than half of them are endangered or threatened. The Canelo Hills ladies’-tresses orchid (Spiranthes delitescens), which is only known to grow in five localities in southern Arizona, was described as a new species in 1990 and listed as an endangered species in 1997. The conservation status of this orchid was feared to be in severe decline, because there was no record of it growing from 2010 to 2015.

The orchid grows in a habitat called cienegas (fresh water wetlands) in southern Arizona. Andrew Salywon, research botanist and associate herbarium curator at the Garden, conducts research on cienega ecology and hydrology and has spent much of his time in the field in this region of Arizona. Through a grant from the U.S. Fish and Wildlife Service, Salywon and a team of researchers from the Garden and Arizona State University began assessing the orchid’s population status.

After not finding any of the orchids in 2015, Salywon and colleagues went on another search this year. On July 28, it was found on private land with help from the family of the land owner. Twelve plants were discovered in this area, and eight additional plants found a few days later.

“We were pretty excited to find the orchid. We spent four days looking and we found it on the last day of a three-day trip. We know it is super rare, and it was pretty cool to find it,” says Salywon.

The Garden partners with the Northern American Orchid Conservation Center, which is a coalition of organizations dedicated to conserving orchids. As part of this effort, seeds and the root of the orchid were collected from the plants. Some of the seeds will be sent to the United States Department of Agriculture, National Center for Genetic Resources Preservation in Ft. Collins, Colorado, for long-term preservation (seed-banking), and some will be sent to a tissue culture lab in order to propagate hundreds of plants so that they can be replanted in the wild and some can be grown in the Garden’s Greenhouses for educational purposes.

The roots of a few plants were sent to collaborators at the Smithsonian Environmental Research Laboratory, where researchers will try and isolate, culture and identify fungi that are closely associated with the roots and are essential for the orchid’s life cycle.

“The seeds of the orchid won’t germinate in the wild without fungus. Essentially, orchid seeds are infected by different species of fungus, which then supplies the orchid’s nutrition during the first year or years of life,” explains Salywon. “By collecting the root of wild orchid, the Smithsonian will have cultures of the associated fungus so that we can grow orchids in the lab with the seed we collected and the native fungi to eventually be reintroduce plants into the wild.”

There is no solid proof why the orchid was missing for six years, but there are multiple hypotheses why it may not be as common as it once was. It may be that these orchids grow better if the wetlands in which they grow do not have a lot of accumulated vegetation.

“Wetlands are very fertile habitats and quickly accumulate lots of vegetation. Without some sort of disturbance, like fires or grazing, the habitat may preclude the small orchids from growing, because other plants shade them out. The landscape might need some type of disturbance to open the habitat in order for the orchids to thrive,” says Salywon.

Another potential reason for the orchid’s lack of growth could be the declining availability of water. Summer precipitation in the area was about average, but the winter rainfall had decreased in the years the orchid was not found.

“There is a statistical significance between winter rainfall and this orchid’s growth. Analysis using incidence data revealed a strong link between orchid occurrence and a series of wet winters. However, this is just a correlation at this point,” explains Salywon.

An additional reason thought to have an impact on the orchid may be groundwater decline. One of the wetlands where the orchid was known from in the past was fed by two springs. Both springs have dried up in recent years.

While the actual reason for the years that this orchid was missing may never be known, the root fungi and seeds of the Spiranthes delitescens can be grown and researched with the hope of reintroducing and repopulating plants into the wild.

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