Thistle Family. «.»1 



much exceeding the inner ones: awns 2. short. Low grounds, waste places: 

 July-September: common.: Johnson and Decatur counties; confused with the 

 preceding which it much resembles. (Vorcujisix inviiluerata Xutt.) 

 * * * Plant* (iqimiU; miliinefscil laircs ttUfmiuly dUmccTcfl. 



B. beck.ii Torr. Water UtivrhjiM. Aquatic perennial This species was 

 observed by Hitchcock in a pond in Story county in 1883 but no specimens 

 were collected. 



HELENIUM Ij. Erect branching perennials, with alternate decurrent 

 leaves, and many-Howe red radiate heads. Rays several, euneate, fertile, 3-.V 

 cieft. Involucral scales linear, reflexed. Receptacle convex to oblong. 

 naked. Pappus of ii-'J one-nerved thin scales. Achenes turbinate, ribbed. 



H- autumnale L. Sneezeweed. Stem 1-6 feet high, nearly smooth, nar- 

 rowly wing-angled; leaves lanceolate, sessile, tapering both ways, toothed; 

 disk and ray-flowers yellow. Pastures, preferring alluvial soil; August- 

 September; common; Winneshiek. Allamakee, Clinton. Scott, Muscatine, Des 

 Moines. Johnson, Floyd. Jefferson. Decatur. Taylor. Fremont, Hancock. 

 Lyon, Dickinson, and Emmet counties: reported from Fayette, Story. Harri- 

 son, and Woodbury counties. 



DYSQDIA Cav. Annual or biennial herbs, dotted withlar.ge pellucid glands 

 which exhale a strong odor. Leaves mostly opposite. Heads many-flowered, 

 usually radiate; rays pistillate. Involucral scales in one row. partially 

 united. Pappus Of one row of scales dissected into capillary rough bristles. 

 Achenes 4-angled. 



D. chrysanthemoides Lagasca. Fetid Manual it. Stem < >— 1 5 inches high, 

 milch branched, smooth: leaves pinnately parted, the divisions narrow, 

 bristle-toothed or out; lreads with a few short raj s. Roadsides and waste 

 places. August-Septrtnber; common; an emigrant from the west. (Z). 

 Ihiiummi ( Vent. ) A. S. Hitchcock). 



ANTHEMIS L. Ours annual branching herbs, with I-.'i-piunately dissected 

 leaves, and solitary terminal heads. Rays white, pistillate or in the first 

 neutra*; disk-flowers yellow. Involucral scales small, scarious, imbricated, 

 shorter than the disk. Pappus wanting or a mere border. Achenes terete or 

 ribbed. 



A. cotula L. Mai/it'ced, Uuij-fenncl. Stem about I foot high, nearly smooth, 

 leaves finely 3-pinnately dissected; pappus none; an ill-scented herb. Road- 

 sides and waste places: June-i'eptember; common. 



A. arvensis L. Corn Chamomile. Similar to the preceding but not ill- 

 scented; stem pubescent; pappus a mere border. This species has been 

 found rarely in Story and Muscatine counties. 



ACHILLEA L. Perennial herbs, with small coryirbose heads, and alter- 

 nate much divided leaves. Heads many-flowered; rays few. fertile. Iuvolu- 

 cral -scales with scarious margins, imbricated. Receptacle convex or flattish, 

 chaffy. Pappus wanting. " Achenes oMong. flattened, margined. 



A. millefolium L. Cainmui'- Yarn.w nr Millt'oit. Stem simple. 1-2 feet high: 

 leaves 2-pinnately-parted; divisions linear, crowded, 3-5-elefu heads in a flat- 

 topped eoryrah; rays 4-5. short, white or rose color. Prairies, fields, and open 

 woods: .Line-September: common. 



CHRYSANTHEMUM L. Perennial herbs, with toothed, divided, or pin- 

 natifid leaves, white fertile rays, and yellow disk flowers. Involucre broad, 

 depressed, of many imbricated scarious-margined scales. Receptacle flat or 

 convex, naked. Pappus wanting. Achenes striate, similar. 



