3G8 Pollard; The Genus Achillea in North America 



to agree perfectly with the white-flowered forms, and are found 

 growhig under simihar conditions, so that they are scarcely worthy 

 of even varietal rank. 



I append a key to the species discussed in detail below. 



Involucre campanulate, its bracts fuscous-margined ; receptacle nearly flat ; ray-flowers 



usually numerous (10-20) ; acheues rather broadly wing-margined. Ptarmica. 



Leaves bipinnate. 



Leaves simple or pinnatirid. 



I. A. dofra/is. 



Corymbs loosely few flowered ; rays exceeding the l)racts. . 



2, A, rtannica. 



Corymbs densely many-flowered ; rays shorter than tTie bracts. 



3. A, mtdilflora. 

 Involucre oblong, the bracts scarcely fuscous-margined ; receptacle convex ; ray- 



EUACHII.LEA. 



flowers few (5-10) ; achenes narrowly margined. 

 Rays usually more than 4 mm. in diameter. 



Leaves with finely divided crowded segments. 

 Leaves with coarser, distinct segments. 

 Rays white. 

 Rays red. 

 Rays less than 4 mm. in diameter. 

 Plant very tall and branching. 

 Plant simple or slightly branched at summit. 

 Ultimate leaf-divisions fdiform. 

 Ultimate leaf-divisions linear. 

 Corymbs dense. 

 Corvmbs loose. 



4. A. laniilosa. 



5 . A. Ca lifo ; n ica , 



o. A. nspkiiifolia. 



7. -•/. Q'r^anfca, 



8. A. Fecteu- Veneris. 



9 . A. MillefoUu ni 

 10. A. li^ustiea. 



T. Achillea borealis Bong. Veg. Ins. Sitch. 149. 



1831. 



Plant very variable hi size, rarely exceeding 4 dm. in height \ 

 stem and leaves usually more or less lanatc, the latter bipinnate 

 with numerous crowded segments, the ultimate divisions minute 

 and acicular : corymb densely circinate, the heads 4—8 mm. in 



height with large white or pink rays 5 mm. in diameter: involu- 

 cral bracts somewhat scarious, with a conspicuous dark fuscous 

 margin : achenes slender, promirrently winged. 



From Labrador and northern British Columbia to Alaska and 



L 



adjacent Siberia, southward in the higher mountain ranges of the 



Pacific slope to Central Mexico. Easily distinguished by its re- 

 . markably handsome heads. The lower leaves are sometimes of 

 very large proportions, similar to those q{ A. Calif ovfiica. 



y 

 I 



2. A. Ptarmic/V L. Sp. PI. 898. - 1753. 



Froni' Newfoundland and Canada to New England, and 

 Michigan. 



