threadleaf groundsel

Threadleaf ragwort is a fast-growing, short-lived (3 to 6 years) bushy perennial shrub growing to 4 feet 6 inches (1.37 m) tall. It is covered by a white close wool. The stems are grooved and the branches are thin, herbaceous above and woody near the base. The leaves are 1 to 5 inches (2.5 to 12.7 cm) long. They are alternate and deeply pinnate, divided into five to nine narrow lobes. These are gray-green above and tomentose. From April to September appear showy yellow flowering heads, 3–4 inches (7.6–10.2 cm) across. They have eight to thirteen sterile ray flowers, and purplish brown disk florets that produce the seeds.

Seeds Dicotyledon fruits; each a 1⁄8 inch (3.2 mm)-long achene that is ribbed and hoary, covered with short white hairs.

S. flaccidus can be found from the central to the southwestern United States, overlapping with the Great Plains region. It is native between Utah and Kansas, south to Arizona, New Mexico and Texas, and much of northern and central Mexico. Like other members of its genus, it prefers disturbed habitats, especially overgrazed rangelands, dried-up streambeds and desert grasslands. It can be found at altitudes between 1,800 and 6,500 feet (550 and 1,980 m). It is common in gravelly washes, dry creek beds, along roads and trails, and mostly away from the coast.

Native

America North-Central U.S.: Kansas, Oklahoma Northwestern: Colorado South-Central: New Mexico, Texas Southwestern: Arizona, Northern Mexico: Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora, Zacatecas Central Mexico: Aguascalientes, Guanajuato, Hidalgo, Jalisco (n.e.), Veracruz Current

America North-Central: Kansas, Oklahoma, Wyoming Northwestern: Colorado South-Central: New Mexico, Texas Southwestern: Arizona, California, Nevada, Utah Northern Mexico: Chihuahua, Coahuila, Durango, San Luis Potosí, Sonora, Zacatecas, Baja California Central Mexico: Aguascalientes, Baja Norte, Guanajuato, Hidalgo, Jalisco (n.e.), Veracruz

Colonizing disturbed areas including over-grazed lands, S. flaccidus helps to achieve a quick groundcover and helps to stabilize the soil for longer-lived perennials.