COMPOSITAE. 379 



526. HELENIUM. 



Erect, simple or branching herbs; leaves all alternate and all 

 but the lower sessile; heads small or large, many-flowered, on 

 naked terminal peduncles; ray-flowers yellow, several or numer- 

 ous, pistillate; disk-flowers yellow or turning brownish or purplish, 

 small and very numerous, all fertile; tegules spreading or re- 

 flexed at maturity; pappus of 5-12 thin or hyaline chaffy scales 

 with or without midribs; akenes top-shaped, striate-ribbed, 

 hairy on the ribs. 



Helenium autumnale grandiflorum (Nutt.) Gray. Perennial, erect, 30-90 

 cm. high, glabrous or puberulent; leaves oblong or ovate-lanceolate, acute, 

 dentate or nearly entire, 5-12 cm. long, decurrent on the stem forming wings; 

 heads few or many, long-peduncled, 10-15 mm. broad; involucre nearly flat, 

 the tegules linear or linear-spatulate, pubescent; ray-flowers 1016, yellow, 

 somewhat drooping, 1-2 cm. long, all fertile; akenes pubescent; pappus 

 scarious, the scales acuminate, awn-pointed. 



River banks, not common. 



527. ACHILLEA. 



Perennial herbs, rather strong-scented; leaves alternate, ser- 

 rate or pinnately dissected; heads small, in corymbs, many- 

 flowered; flowers yellow, white or sometimes rose-colored, all 

 fertile; ray-flowers few or several, mostly short or broad, pis- 

 tillate; involucre narrow, the tegules imbricated in a few rows, 

 appressed; receptacle flattish to conical, with thin chaff; pappus 

 none; akenes oblong or ovate, obcompressed, surrounded by a 

 narrow and cartilaginous margin. 



Achillea millefolium L. Yarrow or Milfoil. Herbage sparingly pubescent, 

 green; stems erect, usually tufted, 30-90 cm. high; basal leaves short-petioled, 

 oblong or oblong-lanceolate, 8-20 cm. long, pinnately divided into very numer- 

 ous segments which are once or twice pinnately-cleft or parted into linear 

 acute lobes; heads small, numerous, in convex or flat-topped terminal corymbs; 

 involucre ovoid or subglobose, 3-5 mm. high; ray flowers 4 or 5, white, 2-4 

 mm. long. 



Abundant in open ground and clearly native. Alpine forms are much 

 dwarfed, often only 15-20 cm. high, and approach A. borealis Bong, of Alaska. 

 A.lanulosaNutt. with very [canescent herbage, common east of the Cascade 

 Mountains, apparently does not occur in our limits. 



528. ANTHEMIS. 



Herbs; leaves alternate, mostly tripinnately divided; heads 

 many-flowered; ray-flowers numerous, commonly conspicuous, 

 pistillate or sometimes sterile; disk-flowers fertile; involucre 

 broad, the tegules very numerous, imbricated and appressed; 

 receptacle convex to oblong-conical, chaffy with mostly slender or 

 thin scales or awns subtending at least the central flowers; pappus 

 none or a short chaffy crown; akenes obovoid or oblong, 4 or 5- 

 angled, 8-10-ribbed or many-striate, truncate at the apex. 



