FWS Focus


Napa bluegrass is a tufted perennial bunchgrass in the grass family found in alkaline sites near thermal springs at two locations near Calistoga in Napa County, California. The species inhabits grasslands and moist, alkaline meadows fed by hot springs between 340 and 400 feet in elevation. Individuals grow from 12 to 39 inches tall. Longer basal leaves grow to about 8 inches long, upper leaves to about 6 inches. A few erect flowering stems appear in May and can grow to 27 inches tall. Pale green to purple flowers bloom in condensed, round-shaped clusters at the end of the few flowering stems. 

Historically, there were only three known populations of Napa Bluegrass, all within a 2-mile radius of Calistoga, California; however, prior to listing one of the populations was extirpated. The combined area of the two remaining populations is slightly more than 1,100 square feet. Historically, Napa bluegrass likely had larger populations before hot spring resources were developed in the Calistoga region.

Threats to the species include climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change
, land conversion, recreational activities, urbanization, stochastic events, competition from invasive plant species, trampling, restricted habitat and range, and alteration of hot spring hydrology.

Scientific Name

Poa napensis
Common Name
Napa bluegrass
FWS Category
Flowering Plants

Location in Taxonomic Tree


Identification Numbers



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