Red Rock sunflower

Helianthus devernii is a herbaceous plant with a perennial habit that regrows each year from an underground branched woody structure atop its roots. The stems reach as much as 102 cm (40 in) in height and lack hairs but have a waxy coating making the surface somewhat whitish. Bone white stems from previous years are persistent and intermingle with the present year's stems. The leaves are attached to the stems directly without a short leaf stem. Each leaf has one prominent vein or nerve, though lower leaves may have two additional indistinct veins. Leaf edges do not have teeth and the lower leaves are attached in pairs on opposite sides of the stems. The leaves nearer the midpoint of the stems are largest measuring 6.8–10.3 cm (2.7–4.1 in) long and usually just 2.8–7.6 mm (0.11–0.30 in) but occasionally as much as 10.3 mm (0.41 in) wide. They have a very narrow, almost grass-like leaf shape but with gently curved sides. Lower leaves of Helianthus devernii have the same shape, but are shorter, 4.1–5.6 cm (1.6–2.2 in) long and 4.4–9.0 mm (0.17–0.35 in) wide, and are usually shed by the time the plant flowers. Leaves get shorter and thinner further up the stems ranging from 2.6–6.4 cm (1.0–2.5 in), though usually shorter than 5.1 cm (2.0 in), and just 1.2–1.7 mm (0.05–0.07 in) wide with a very thin and grasslike shape. …

The perennial herb is found within and around a small portion of Red Rock Canyon National Conservation Area in Clark County, Nevada—a BLM-managed National Conservation Area within the Mojave Desert. Helianthus devernii has been found at two desert spring locations with moist alkaline soils. About 38% of the plants are located on BLM lands, 62% of the plants are on adjacent private inholdings. Original counts put the total number of individuals at around 400. Further surveys increased the total known number of individual plants to 725.