Pursh provides an extended description and reports the plant as found "In open prairies on the Missouri. . . . Aug. Sept." Meehan (1898: 30) lists the specimen as Haplopappus spinulosus (Pursh) DC. (Prodr. 5: 347. 1836, as "Aplopappus"). Cutright refers it to Sideranthus spinulosus Sweet (Hort. Brit. 227. 1826). The lectotype was collected along the Missouri River in Lyman or Brule Co., South Dakota, on 15 Sep 1804, possibly near the mouth of the White River where other items were found (Moulton, 1987a: 469). (The Lewis & Clark Herbarium Digital Imagery Study Set, ANSP, 2002) On deposit at the Academy of Natural Sciences, Philadelphia Collected by:Meriwether Lewis & William Clark Collection date:09/15/1804