Calistoga Allocarya

Calistoga allocarya is an annual herb in the borage family found in alkaline sites near thermal springs at two locations near Calistoga in Napa County, California. The species inhabits pools and swales adjacent to and fed by hot springs and small geysers in grasslands between 300 and 500 feet in elevation. The extant populations occur on clay soils characterized by high concentrations of boron, arsenic, and sulfate. 

An individual plant can grow from 4 to 16 inches tall from a single stem at the base. Small, usually paired, white flowers appear in March to April in a slender, unbranched inflorescence. The fruit is a tiny, egg-shaped nutlet, keeled on the back and covered with smooth, wart-like projections.

Historically, there were only three known populations of Calistoga allocarya, all within a 2-mile radius of Calistoga, California; however, prior to listing one of the populations was extirpated due to urbanization and agricultural land conversion. The combined area of the two remaining populations is less than 900 square feet. 

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.