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

Apiaceae

The Apiaceae , commonly known as carrot or parsley family, is a group of mostly aromatic plants with hollow stems. The family is large, with more than 3,700 species spread across 434 genera, it is the sixteenth largest family of flowering plants...

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

Oregon

Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...

 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 50 miles. The three separate groups are located in the Klamath Mountains

Klamath Mountains

The Klamath Mountains, which include the Siskiyou, Marble, Scott, Trinity, Trinity Alps, Salmon, and northern Yolla-Bolly Mountains, are a rugged lightly populated mountain range in northwest California and southwest Oregon in the United States...

 and on either side of the Cascade Range

Cascade Range

The Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...

.

This plant is a perennial herb growing up to 1.2 meters in height. The roots are pink to reddish brown in color. The inflorescence

Inflorescence

An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...

 is an umbel

Umbel

An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....

 of tiny white flowers. Blooming occurs in July through September.

This species grows on valley floors in heavy clay soils. The habitat is prairie

Prairie

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

, pasture, and the edges of woodlands. Other plants in the habitat may include tufted hairgrass (Deschampsia cespitosa) and California oatgrass

Danthonia californica

Danthonia californica is a species of grass known by the common name California oatgrass. This plant is native to two separate regions of the Americas, western North America from California to Saskatchewan, and Chile.-Description:...

 (Danthonia californica).

Threats to this rare species include housing development, agriculture and grazing, herbicide

Herbicide

Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...

s, introduced species

Introduced species

An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...

, and nickel

Nickel

Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...

mining.

It has been proposed that one of the three groups of populations may represent a separate species.