California Native Orchid is Endangered, Say International Scientists

Cypripedium californicum | Photo: Scott Wilson/Flickr/Creative Commons License

A California native orchid once found from the Bay Area and Sierra Nevada northward into Oregon has declined in population so steeply that the International Union for the Conservation of Nature (ICUN) has declared the plant globally Endangered.

Cypripedium californicum, also known as the California lady's slipper orchid, grows up to three feet tall with as many as 20 white flowers on a stem. It's restricted to wet soil such as stream banks in open conifer forests, and the last century's worth of clearcutting in those forests has proven disastrous for the species. So has collection for the horticultural trade.

The listing was part of a major update to the ICUN's Red List of Threatened Species, in which 817 species were newly listed under various categories of threat. That includes 79 percent of the world's known slipper orchid species such as Cypripedium californicum.

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"What was most surprising about this assessment was the degree of threat to these orchids," said Hassan Rankou, the IUCN Species Survival Commission's (SSC) Authority for the Orchid Specialist Group, "Slipper orchids are popular in the multimillion-dollar horticultural industry. Although the industry is sustained by cultivated stock, conservation of wild species is vital for its future."

Though the orchid was found along streambanks in Marin County north of San Francisco as recently as 2004, it's apparently been extirpated from the county and now grows no farther south than in the logged-over hills between Sebastopol and the coast. It can also be found in places in the northern Sierra Nevada, and as far north as Josephine and Curry counties in Oregon.

Clearcutting damages the plant not only by changing stream flow patters and introducing the risk of trampling but also by allowing more sunlight into the forest, making things a bit too bright for the shade-loving plants. Though clumps of up to a thousand plants do exist, the orchid is more commonly found in groups of ten or fewer, making local populations far more vulnerable to inadvertent damage or unethical collecting.
 
Also added to the Red List were two other Californian Cypripedium species -- Cypripedium montanum, the Mountain Lady's Slipper, and Cypripedium fasciculatum, the clustered lady's slipper -- both of which were listed as "Vulnerable," a lesser threat ranking in which the ICN considers the species to face a "high risk of extinction in the wild," as compared to "Endangered" status of "very high risk."

The IUCN's assessment of threats to the California lady's slipper orchid is essentially a capsule history of human activity in the state's conifer belt:

C. californicum is under numerous threats especially habitat loss and disturbance of its restricted range due to urbanization, clear-cutting, suppression of natural disturbance regimes, logging practices, accidental trampling, climate change, mining activities and collection which cause a continuing decline of the species on the estimated locations and the destruction of some subpopulations (e.g. Marin County population is already destroyed).

Cypripedium californicum isn't protected under the federal or state Endangered Species Acts, though the California Department of Fish and Wildlife does list the orchid as a "special" species deserving conservation attention. The California Native Plant Society classifies the California lady's slipper as "Rare."

The IUCN recommends conservation of the plants' habitat, especially on so-called serpentine seep areas. It also urges legal bans on collecting of the plants.

In other state-related IUCN news, a California native insect, the Sacramento beetle (Anthicus sacramento), was retained on the Endangered list as the result of a review of the species' status. First listed by IUCN in 1996, the beetle is restricted to two sand dune habitat sites in the Sacramento area, one of them a garbage dump and the other a popular off-road vehicle area.

About the Author

Chris Clarke is a natural history writer and environmental journalist currently at work on a book about the Joshua tree. He lives in Joshua Tree.
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