National Collection of Rare and Endangered Plants

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By: Cheryl Birker, California Botanic GardenDuncan Bell collects Panamint Mountains buckwheat at Death Valley NP

Bringing Rarity Together

The Center for Plant Conservation maintains a collection of more than 2,200 of America’s most imperiled native plants through its network of world class botanical gardens. Our 73 Institutional Conservation Partners safeguard endangered plant material in “ex situ” botanical collections including seed banks, nurseries, and garden displays. An important conservation resource, the National Collection serves as an emergency backup in case a species becomes extinct or no longer reproduces in the wild. To communicate this important work, CPC and its network of conservation experts actively update web profiles for all National Collection species, which serve as a historical record of conservation actions taken to save these rare plants. Search the National Collection and view the plant profiles to learn more about these beautiful, imperiled rare plants and the gardens that conserve them.

Collection Statistics

Institutional Conservation Partners
Species in the National Collection
Conservation Collections

Canelo Hills Ladies’-tresses

(Spiranthes delitescens)

Canelo Hills Ladies’-tresses (Spiranthes delitescens) is a critically imperiled orchid species endemic to southern Arizona. Small white flowers line the twisting inflorescence of this terrestrial orchid, with as many as 40 flowers appearing on each inflorescence. There are currently just two known extant populations of this rare species, and it is listed as Endangered under the federal Endangered Species Act. The cienega habitat, a type of marshy wetland in the Southwest, that this species calls home is limited in availability and the two known remaining populations exist on private land.

Scientists at Desert Botanical Garden have been working with the U.S. Fish and Wildlife Service, the Smithsonian’s North American Orchid Conservation Center, and private ranchers to conserve this species through propagation and fungal research. Researchers are also working with trained ecological scent detection dogs to locate new individuals and subpopulations as well as historical populations that have not been documented for decades. This orchid is held in the CPC National Collection at Desert Botanical Garden, Arizona Sonora Desert Museum, and Cincinnati Zoo & Botanical Gardens.

Learn more about conservation actions taken for Canelo Hills Ladies’-tresses on its National Collection Plant Profile, and help support critical conservation work for this species with a Plant Sponsorship.

Background photo: Canelo Hills Ladies'-tresses (Spiranthes delitescens) in flower. Photo credit: Steve Blackwell.

CPC National Collection Search

The Center for Plant Conservation’s National Collection of Endangered Plants contains plant material for more than 2,000 of the country’s most imperiled native plants. An important conservation resource, the National Collection is a backup in case a species becomes extinct or no longer reproduces in the wild. Search the National Collection and view the plant profiles to learn more about these beautiful, imperiled plants.

Visit our Rare Plant Finder for a More Advanced Search
By: Jennifer Possley Passiflora sexflora

Sponsor a Plant in the National Collection

To offset some of the expenses of collecting, growing, and researching plant species in the National Collection, the Center for Plant Conservation created the Plant Sponsorship Program to provide Participating Institutions responsible for a named species stable funding for the long-term work. A sponsorship does not cover all the expenses, but it provides significant help and stability, and has a critical and lasting impact on plant conservation efforts.

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With your help we can safeguard more of the unique plants in peril and in need of protection by adding them to the National Collection and conserving them in the wild.

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