Matricaria discoidea DC.

Chamomilla suaveolens (Pursh) Rydberg
Santolina suaveolens Pursh, Fl. Am. Sept. 520. 1814.
Artemisia matricarioides Less. Linnaea 6: 210. 1831.
Colula matricarioides Bong. Mem. Acad. St.-Petersb. VI. 2: 147. 1832.
Tanacelum suaveolens Hook. Fl. Bor. Am. 1: 327. 1833.
Matricaria discoidea DC. Prodr. 6: 50. 1837.
Tanacetum pauciflorum DC. Prodr. 6: 131. 1837. Not T. paiiciflorum Richards. 1823.
Matricaria tanacetoides Fisch. & Mey. Ind. Sem. Hort. Petrop. 7: 52. 1840.
Lepidanlhus suaveolens Nutt. Trans.' Am. Phil. Soc. II. 7: 397. 1841.
Ceuocline pauciflora C. Koch, Bot. Zeit. 1: 41. in part. 1843.
Lepidotheca suaveolens Nutt.; T. & G. Fl. N. Am. 2: 413, as synonym. 1843.
Tanaceiuyn matricarioides Less.; Ledeb. Fl. Ross. 2: 544. as synonym. 1846.
Akylopsis suaveolens Lehm. Ind. Sem. Hort. Hamb. 1850: 3. 1850.
Chamomilla discoidea J. Gay; A. Br. Bot. Zeit. 10: 650. 1S52.
Matricaria matricarioides Porter, Mem. Torrey Club S: 341. 1894.
Matricaria suaveolens Buch. Fl. Brem. ed. 4. 142. 1894. Not M. suaveolens L. 1755.
A leafy annual; stem !-3 dm. high, striate, branched, glabrous; leaves 2-4 cm. long, glabrous, bior tri-pinnatifid into short linear-filiform divisions; heads numerous, discoid; involucre saucer-shaped, 3 mm. high, 5-8 mm. broad; bracts in 2-3 series, subequal, elliptic, rounded at the apex, with white, scarious margins; receptacle conic, hollow; ray-flowers wanting; disk-corollas greenish-yellow, 1.5 mm. long; tube slightly longer than the campanulate throat; lobes 4, ovate; achenes greenish-brown, oblique, with 4 ribs on the inner side, smooth on the back and between the ribs; crown of the pappus minute or obsolete.
Type locality; Banks of the Kooskoosky [Clearwater River, Idaho).
Distribution: Native from Alaska to Montana, Arizona, and Lower California; naturalized eastward to Newfoundland, New Jersev, and Missouri; also in eastern Siberia; adventive in Europe.