''Perideridia erythrorhiza'' is a rare species of flowering plant in the family

Apiaceae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus '' Apium'' and commonly known as the celery, carrot or parsley family, or simply as umbellifers. It is the 16th-largest family of flowering plan ...

known by the common names western yampah and redroot yampah. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

in the United States, where there are about 20 occurrences. The populations occur in three regions in southwestern Oregon, which are separated by more than .''Perideridia erythrorhiza''.
The Nature Conservancy. The three separate groups are in the

Klamath Mountains The Klamath Mountains are a rugged and lightly populated mountain range in northwestern California and southwestern Oregon in the western United States. As a mountain system within both the greater Pacific Coast Ranges and the California Coast ...

and on either side of the Cascade Range.''Perideridia erythrorhiza''.
Center for Plant Conservation. This plant is a perennial herb growing up to in height. The roots are pink to reddish brown in color. The

inflorescence An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...

is an

umbel In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' "p ...

of tiny white flowers. Blooming occurs in July through September. This species grows on valley floors in heavy clay soils. The habitat is

prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

, pasture, and the edges of woodlands. Other plants in the habitat may include tufted hairgrass (''Deschampsia cespitosa'') and California oatgrass (''Danthonia californica''). Threats to this rare species include housing development, agriculture and grazing, herbicides,

introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

, and

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

mining. It has been proposed that one of the three groups of populations may represent a separate species.Meinke, R. J. (2006)
Experimental outplanting of ''Perideridia erythrorhiza'' ("Klamathense") on the Fremont-Winema National Forest.
Prepared for the Fremont-Winema National Forest under Agreement Number 2003-CS-11060220-020.

References

{{Taxonbar, from=Q7168435 erythrorhiza Flora of Oregon Endemic flora of Oregon Endemic flora of the United States