Oregon Semaphore Grass - Center For Plant Conservation
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Oregon Semaphore Grass (Pleuropogon oregonus)

Where is this rare grass? It?s the taller patch in the center of the photograph, just above the small pond. Photo Credit: V. Crosby
  • Global Rank: G1 - Critically Imperiled
  • Legal Status: N/A
  • Family: Poaceae
  • State: OR
  • Nature Serve ID: 145307
  • Date Inducted in National Collection: 04/01/1990

The very existence of Oregon semaphore grass has been a recurring question over the past 100 years. In 1886, William C. Cusick first collected this grass in what was once called Hog Valley in northeastern Oregon, and another collection was made in Union, Oregon in 1901. It was not collected again until 1936, when M.E. Peck discovered it in the southern part of the state (in Lake County, Oregon). It was not seen or collected again for nearly 40 years and was reported as presumably extinct or endangered in the late 1970s. In 1979, Jimmy Kagan of the Oregon Natural Heritage Program diligently scoured a site along Mud Creek in Lake County until he found this particular grass (But 1985). This was probably the same location Peck had made his collection 45 years before. In 1986, USFS botanist Andy Kratz was determined to lead a thorough search for the Hog Valley population. There was no place officially called "Hog Valley", as it was a name that had been used by locals, but was apparently not commonly used any longer. There was no documentation telling him where to look, so he relied on personal communication with people who lived in the region. Mr. Kratz was eventually directed to an enthusiastic landowner in Union County willing to help him in his search. He was successful in finding the previously documented site in "Hog Valley" as well as 3 new locations nearby in Union County, Oregon. He surveyed surrounding counties including Baker, Harney, Grant, Umatilla, Wheeler, and Morrow but made no discoveries (Kratz 1986). Today, scientists are still only aware of the two main populations of this rare plant. Although the range is so limited, the U.S. Fish and Wildlife Service removed this plant from candidate status in 1996 because the threats from grazing and stream channelization appeared minimal. It is, however, listed as Threatened by the state of Oregon.

Where is Oregon Semaphore Grass (Pleuropogon oregonus) located in the wild?


Pleuropogon oregonus grows in moist meadows and marshland often comprised of gravelly silt loam or clay soil inundated by sluggish water at elevations of around 2450-3950 ft (750 to 1200 m). It is found growing with other grasses and sedges.


OR: Eastern Cascades (Lake County), Blue Mountains (Union County)

States & Provinces:

Oregon Semaphore Grass can be found in Oregon

Which CPC Partners conserve Oregon Semaphore Grass (Pleuropogon oregonus)?

CPC's Plant Sponsorship Program provides long term stewardship of rare plants in our National Collection. We are so grateful for all our donors who have made the Plant Sponsorship Program so successful. We are in the process of acknowledging all our wonderful plant sponsorship donors on our website. This is a work in progress and will be updated regularly.

Conservation Actions

Nature Serve Biotics
  • 05/02/2017

An Oregon endemic, currently known from 2 areas of the state. This species had not been collected in nearly half a century and was feared extinct when it was rediscovered in 1983 in southcentral Oregon. The previous collections had been made in northeastern Oregon, and the species was rediscovered in that area in 1986. There are now 8 populations known, one portion of which is being protected by The Nature Conservancy. Otherwise all sites are on private land with no protections. Changes in hydrology or grazing regime thus threaten all natural populations. Climate change may further reduce suitable habitat. Revisiting sites from 1980s would help to clarify short-term trends.

  • 01/01/2010

Land drainage for conversion to grazing or cropland (Kratz 1986). Low seed set and moderate seed viability significantly reduces sexual reproduction (But et al. 1985). Excessive cattle grazing during periods of active plant growth, flowering and seed

  • 01/01/2010

2 populations. 1 in northeastern Oregon (Union County) and one in southern Oregon (Lake County) (ONHDB and Gisler, pers. comm.). All populations are on private pastureland. A portion of a property in Lake County is managed by The Nature Conservancy.

  • 01/01/2010

Tests of the pollen using four enzyme systems suggest approximately 87% viability (But, 1985). Germination trials at The Berry Botanic Garden revealed that germination was greatest (100%) under a cold stratification period followed by a constant 68F (20C) treatment. When first subjected to 8 weeks of cold stratification and then subjected to alternating 50F/68F (10C/20C) temperatures, 71% of seeds germinated. Seeds that were placed directly in a 68F (20C) chamber without cold stratification had germination of 83%, and of those placed directly in alternating 50F/68F (10C/20C) temperatures, only 50% germinated (BBG File). Investigation of seed production, seed germination and cultivation of this species (Gisler, pers. comm.). Taxonomic comparison of the two extant populations (Gisler, pers. comm.). Analysis of ecological data to help predict suitable introduction habitats (Gisler, pers. comm.).

  • 01/01/2010

Plants are being cultivated for a planned re-introduction project in 2002 (Gisler, pers. comm.). Part of one population is on private land that is managed by The Nature Conservancy. They have fenced off the area and left it undisturbed for many years. However, observations indicate that the nearby grazed areas are more dense and lush that the ungrazed, suggesting that limited grazing by cattle may benefit the plant by removing thatch buildup (Welty 2001).

  • 01/01/2010

Conduct studies to determine the effect of light cattle grazing after seed has fallen or before plants begin re-growth in the spring.

  • 01/01/2010

Collect and store seeds from known populations.


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Taxon Pleuropogon oregonus
Authority Chase
Family Poaceae
CPC Number 3529
ITIS 42030
Common Names Oregon semaphore grass | Oregon semaphoregrass
Associated Scientific Names Pleuropogon oregonus | Lophochlaena oregona
Distribution OR: Eastern Cascades (Lake County), Blue Mountains (Union County)
State Rank
State State Rank
Oregon S1
Ecological Relationships

Pleuropogon oregonus blooms from early June to late July and fruits from late July to mid August. For the number of possible fruits that it could produce, an extremely low number actually develop and are viable. The low fecundity (reproductive success) may contribute to the rarity of Pleuropogon oregonus (But et al. 1985). In the absence of extensive sexual reproduction, this grass spreads extensively by rhizomes. However, this creates large areas of plants that are genetically identical (ONHDB 2000).Associated Species include: Carex athrostachya, Eleocharis palustris, Beckmannia syzigachne, Deschampsia danthonioides, Glyceria borealis, Hordeum brachyantherum and Poa nevadensis (But et al. 1985).


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