308 CAEDUACEAE. 



the same length. Anthers oblong. Achenes nearly or quite as long as the 

 corollas. Pappus of the ray of several bristles or wanting, of the disk of 

 lacerate or fimbriate bristles. 



1. G. parviflora Cav. Plants 1-7 dm. tall, often branched: leaf -blades ovate 

 to ovate-lanceolate, 2-5 cm. long, petioled: involucre 2-2.5 mm. high; outer 

 bracts ovate, obtuse: ligules white, 1-1.5 mm. wide: disk-corollas about 1.5 

 mm. long : achenes less than 2 mm. long. — Common, in cultivated grounds 

 and waste jilaces. Nat. of S. Am. — Sum. 



38. HELENIUM L. Annual, biennial, or perennial, bitter herbs. Leaves 

 alternate : blades entire, toothed, or pinnatifid, often decurrent. Heads soli- 

 tary, few, or numerous. Involucre flattish: bracts spreading or reflexed. Re- 

 ceptacle conic, oblong, or subglobose. Eay-flowers several, the corollas with 

 cuneate ligules. Disk-corollas with broadly ovate lobes. Achenes ribbed. 

 Pappus of 5-8 acuminate or awn-tipped scales. 



1. H. autumnale L. Plants 2-9 dm. tall: leaf -blades oblong to elliptic, or 

 slightly broadest above the middle or below it, 3-12 cm. long, rather promi- 

 nently toothed: involucral bracts linear-lanceolate or narrower, 5-7 mm. long: 

 ligules 10-20 mm. long: disk yellow; corollas 3 mm. long. — Common, in 

 swamps and low grounds. — Fall. — Sneezeweed. 



39. ACHILLEA [Vaill.] L. Perennial herbs. Leaves alternate: blades 

 toothed, pinnatifid, or dissected. Heads small, corymbose. Involucre cam- 

 panulate to obovoid: bracts broad, firm. Eay-corollas with ligules mostly 

 broader than long. Achenes flattened and callous-margined. Pappus wanting. 



1. A. Millefolium L. Plants 2-9 dm. tall, villous and cottony: leaves 5-22 

 cm. long; blades twice or thrice pinnately parted: heads crowded: inner bracts 

 of the involucre oblong, 3.5-4.5 mm. long, ciliate: ray-flowers 4 or 5, the 

 ligules 3-4 mm. wide, white or pink: achenes 1-1.5 mm. long.- — Common, on 

 banks and in meadows and fields. (Eurasia.) — Sum. — Milfoil. Yarrow. 



40. ANTHEMIS [Mich.] L. Annual, biennial, or perennial herbs. 

 Leaves alternate: blades pinnatifid or dissected. Heads relatively large, mostly 

 scattered. Involucre hemispheric: bracts relatively long. Eay-corollas with 

 elongate ligules. Achenes not flattened. Pappus often crown-like. — Sum. — 

 Chamomile. 



Leaf-blades 3-pinnately dissected : achenes with tuberculate sides. 1. A. Cotula. 

 Leaf -blades 1-2-pinnateIy parted : achenes with smooth sides. 2. A. arvensis. 



1. A. Cotula L. Annual, ill-scented: leaf -blades thrice pinnately dissected, 

 the segments very slender: disk-flowers near the center of the receptacle with 

 bractlets; corollas mostly 2.5 mm. long: achenes tuberculate-roughened: 

 pappus wanting. — Common, in waste places and on roadsides. Nat. of Eu. 

 — May-weed. Dog-fennel. 



2. A. arvensis L. Annual or biennial, not ill-scented: leaf -blades once or 

 twice pinnately parted, the segments relatively coarse: disk-flowers all with 

 bractlets; corollas mostly 2 mm. long: achenes smooth-sided: pappus a narrow 

 border. — Occasional, in fields and on roadsides. Nat. of Eu. — CoRN- 

 chamomile. 



41. CHEYSANTHEMUM [Tourn.] L. Annual or perennial herbs. 

 Leaves alternate: blades toothed, incised, or dissected, the segments coarse. 

 Heads solitary or clustered. Involucre saucer-shaped or hemispheric: bracts 



