Longleaf Wormwood

Artemisia longifolia Nutt. Gen. 2 : 142. 1818
Arlemisia integrifolia Vurs^ii.VX. Am. Sept. 520. 1814. t^ot A. integrifolia'L,. 1753. Artemisia ludoviciana integrifolia A. Nelson, First Rep. Fl. Wyo. 138. 1896. Artemisia natronensis A. Nelson, Bull. Torrey Club 26: 485. 1899.
A perennial, with a horizontal rootstock; stem 3-10 dm. high, white-tomentose; leaves linear or linear-lanceolate, 6-15 cm. long, often revolute, loosely floccose or in age glabrate above, white-tomentose beneath, sometimes caudate-attenuate; heads many in a narrow panicle, mostly erect and peduncled; involucre rounded-campanulate, 4-5 mm. high, 3-4 mm. broad, densely tomentose; bracts about 12, in about 3 series; outer bracts ovate, acute, fully half as long as the innermost; irmer bracts oval, acute; ray-flowers 5-8; corollas nearly 2 mm. long; disk-flowers 15-25; corollas light-yellow, nearly 3 mm. long; achenes nearly 2 mm. long. {A. natronensis is a form with somewhat broader and shorter leaves.)
Type locality: Banks of the Missouri, at the confluence of White River, South Dakota.
Distribution: Manitoba to Nebraska, Oregon, and Washington.