CARDUACEAE. 



403 



18. ACHILLEA [Vaill.] L. 



Plerbs, mostly perennial, with erect, leafy stems, finely dissected, pinnatifid 

 or serrate alternate leaves, and small heads of both tubular and radiate flowers, 

 corymbose at the ends of the stem and branches. Involucre obovoid, or cam- 

 panulate, its bracts appressed. Imbricated in few series, the outer shorter. 

 Eeceptacle nearly flat, or convex, chaffy, the membranous chaff subtending the 

 disk-flowers. Ray-flowers pistillate, fertile, the rays white or pink. Disk- 

 flowers perfect, fertile, their corollas yellow, 5-lobed. Anthers obtuse and 

 entire at the base. Style-branches of the disk-flowers truncate. Achenes ob- 

 long or obovate, slightly compressed. Pappus none. [Named for Achilles.] 

 About 75 species, natives of the northern hemisphere, mostly of the Old World. 

 Type species: Achillea santolina L. 



1. Achillea Millefdlium L. 



Yarrow. Milfoil. (Fig. 444.) 

 Perennial from horizontal root- 

 stocks ; flow^ering stems sparsely 

 pubescent, or nearly glabrous, 

 simple, or corymbosely branched 

 above, l°-2° high. Basal leaves 

 and those of the numerous short 

 sterile shoots mostly petioled, 

 sometimes 10' long and V wide, 

 those of the stem sessile, all 

 somewhat pubescent or nearly 

 glabrous; heads numerous, 2"- 

 3" broad, in terminal compound 

 dense, somewhat convex cor- 

 ymbs; involucre ovoid, its 

 bracts oblong, stramineous with 

 greenish keel, obtusish, pubes- 

 cent; rays 4-6, white, or often 

 pink or purple. 



Grassy woods, Devonshire, 

 1905. Introduced. Native of the 

 north temperate zone. Flowers 

 in summer and autumn. 



19. ANTHEMIS [Micheli] L. 



Annual or perennial herbs, with pinnatifid or dissected, alternate leaves, 

 and usually large peduncled heads of both tubular and radiate flowers, termi- 

 nating the branches. Involucre hemispheric, its bracts imbricated in several 

 series, scarious-margined, appressed, the outer shorter. Eeceptacle convex, 

 conic or oblong, chaffy at least toward the summit, the chaff subtending the 

 disk-flowers. Ray-flowers pistillate and fertile, or neutral, the tube terete or 

 2-winged, the ray white or yellow, entire or 2-3-toothed. Disk-flowers perfect, 

 fertile, yellow, their corollas Avith 5-cleft limbs. Anthers obtuse and entire at 



