Ute ladies'-tresses: A case study

Ute ladies'-tresses: A case study

Ute ladies'-tresses (Spiranthes diluvialis) is a small perennial orchid protected under the federal Endangered Species Act. Boulder Valley contains Colorado's single largest known population of the orchid.

Ute ladies'-tresses are native to wetlands. Today however, over 80 percent of the orchid plants on City of Boulder Open Space land are found in irrigated hay meadows. Without irrigation, these meadows would become short grass prairie--too dry for orchids.

When the orchid was first listed as a threatened species, Open Space managers thought that grazing would further harm it. They banished the cows. But without grazing, weeds such as Canada thistle proliferated and the orchid populations dropped. When land managers allowed grazing to resume, the thistle infestation was reduced, and the orchid reappeared.

In Boulder Valley, survival of the Ute ladies'-tresses orchid now depends upon human intervention through both irrigation and grazing. Does this dependence on humans make the orchid less native?

Right: Ute ladies'-tresses in bloom. Photo courtesy of Boulder Open Space and Mountain Parks.

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