About Helianthus exilis A.Gray
Helianthus exilis A.Gray is a species of sunflower with the common name serpentine sunflower. This plant is endemic to northern California, growing from Siskiyou County south to Napa County and Nevada County. In this region it grows mainly in mountainous areas, and is often found in serpentine soils.
Helianthus exilis is an erect annual that grows to heights over 1 meter (40 inches). It has a hairy, rough stem with leaves that are lance-shaped or oval. The leaves are usually pointed, sometimes have serrated edges, and measure 3 to 15 centimeters (1.2–6.0 inches) long. One or more flower heads grow per inflorescence, and each plant can produce many inflorescences that grow along the full length of the stem. Each flower head has a cup of long, pointed phyllaries that hold an array of bright yellow ray florets; each ray floret is one to two centimeters (0.4–0.8 inches) long, and surrounds a center of yellow to dark purple or reddish disc florets. The achene produced by this species is 3 to 5 millimeters (0.12–0.20 inches) long.
