Northern Prairie Wildlife Research Center
Also sometimes called "prairie ragwort," Platte ragwort occurs throughout North Dakota. Elsewhere, the plant can be found from North Carolina to the Northwest Territories and south to Texas at elevations up to 7,000 ft.
Platte ragwort is a biennial or short-lived perennial from a tough base (caudex) that also sometimes bears runners (stolons). Stems are usually single, about 10 to 20 inches tall, and often bear loose patches of cotton-like hairs. Basal leaves are variously toothed to almost smooth-margined and are up to 4 inches long. Leaves become much smaller upward. Six to 20 yellow flower heads about one-inch wide form in a corymb (flat-topped cluster whose flowers progressively mature from the margin inward). Fruits are cylindrical, ribbed achenes.
Look for Platte ragwort in early June on native pastures. My records show greater abundance of the plant under heavy or moderately-heavy grazing by cattle. Many Senecios, including several trees, are used economically worldwide as medicines, foods, and ornamental woods. Others poison horses and cattle. However, I could find no mention of Platte ragwort in these regards.
Ragworts are members of the sunflower family (Asteraceae). In this family, many flowers are often arranged into flower heads that are often mistaken for a single flower. The family contains over 15,000 species, more than in any other family in North Dakota as well as in most countries in the North Temperate Zone.
Senecio is an immense, worldwide genus of over 1,000 species, the name derived from the Latin senex, "an old man," likely in reference to the pale or gray appearance of many species. The Senecios are often called "groundsels." The specific name plattensis means "of the Platte River region" in botanical Latin. Platte ragwort was first described for science in 1841 by the eminent English botanist-naturalist Thomas Nuttall (1786-1859). He visited the Mandan villages along the Missouri River in 1810-1811.