And another thank you to David Tarrant, retired UBC Botanical Garden staff member, for photographs from the central highlands of Mexico.
In his correspondence with me, David relayed the following observations: “There is quite a decent population of [these orchids] above Las Cabras in the Picachos. They seem to survive amongst rocks and cacti, which probably helps protect them from grazing animals.” This particular plant was blooming on the edge of an oak forest.
Online information about Dichromanthus aurantiacus is difficulty to come by, in part due to changing names. At least fourteen different scientific names have been applied to this taxon, including Spiranthes aurantiaca and Stenorrhynchos aurantiacus (aurantiacus means “orange”), with Dichromanthus aurantiacus only having been published in 2002. One of the sites with the best snippets of information is the Internet Orchid Species Photo Encyclopedia (Dichromanthus aurantiacus), which provides a description of the plant, habitat, and distribution (wet montane forests of Mexico, Guatemala, El Salvador and Honduras).
The Arizona-Sonora Desert Museum’s Center for Sonoran Desert Studies has a research program into the Sierra Madre Occidental of Eastern Sonora, Mexico (Yécora region). Along with a gallery of plants one might find associated with Dichromanthus aurantiacus (here named Stenorrhynchos aurantiacus), reading the other pages from the research program provides many details about this intriguing region.