Claim: Helianthus exilis is a species of sunflower reaching over a meter (40 inches) of the genus Helianthus, from the Asteraceae family that is endemic to northern California, from Siskiyou County south to Napa County and Nevada County.
Evidence: Helianthus exilis is a species of sunflower known by the common name serpentine sunflower. Helianthus exilis is an erect annual reaching heights over a meter (40 inches)). Genus: Helianthus Family: Asteraceae It is endemic to northern California (from Siskiyou County south to Napa County and Nevada County), where it grows mainly in mountainous areas, often in serpentine soils.