Enceliopsis argophylla

Enceliopsis argophylla, commonly known as the silverleaf sunray, is a North American species of flowering plant in the family Asteraceae. Other common names include nakedstem sunray and naked-stemmed daisy. It is native to the southwestern United States: Arizona, Nevada, and Utah, and can be seen a short distance east of Las Vegas, Nevada.

Description

Enceliopsis argophylla is a perennial herb up to tall, appearing silvery because of many small hairs pressed against the leaves. Leaf blades are up to long, with wings running along the sides of the petioles. Appearing in April and May, the flower heads are yellow, at the ends of long peduncles, each head with as many as 35 ray florets and up to 500 tiny disc florets. The achene is strongly flattened, covered with small hairs, and sometimes with a pappus of 2 awns up to 2 mm long.
American botanist Daniel [Cady Eaton] described the silverleaf sunray as Tithonia argophylla in 1871.

Distribution and habitat

Found in Clark and Mohave Counties in the vicinity of the artificial reservoir Lake Mead, it grows on stony barren slopes at altitude. It often grows alongside the rare golden bear-claw poppy or Las Vegas bear-poppy Arctomecon californica. Both plants grow in a fragile gypsum crust on the soil, which when damaged facilitates the spread of invasive plants. Its habitat is threatened by the reservoir as well as off-road recreational vehicle use.