152 SELECTED WESTERN FLORA 



28. HELIANTHUS. Sunflower. 



Heads many-flowered, radiate; rays spreading, neutral; disk 

 flowers perfect; receptacle flat, covered with persistent chaflf which 

 encloses the achenes; pappus 2 or more thin deciduous scales. 

 Erect, mostly branched, annual or perennial herbs with simple 

 leaves and large showy heads with yellow rays, Elnd yellow, brown, or 

 purplish disks. 



* Annuals. 



1. H. petioUris, Nutt. 



Somewhat slender; leaves oblong to lanceolate. Light soil, S. W. Man. 

 and westward. 



** Pebennialb. 



t Disk bhownish-pueple. 



2. H. scabSrrimus, Ell. 



Stout, erect, 1-6 ft. high, sparingly branched; leaves ovate to oblong, 

 short-petioled, serrate, 3-nerved, thick, rigid, and rough on both sides, all 

 opposite except the uppermost, which are bract-like; heads large, usually 

 solitary. (H. rigidus, Desf.) Moist prairies, Man.-Alta. 



3. H. subrhomboideus, Rydb. 



Very closely resembling the preceding. The leaves are less sharply ser- 

 rate and the stem usually tinged with red. Often included in H. acaber- 

 rimus, and the more common northern form. Prairies, Man.-Alta. 



tt Disk yellowish. 



4. H. giganteus, L. 



Stem erect from a creeping, often tuberous rootstock; 2-10 ft. high, 

 branched above, rough hairy towards the top; leaves mostly alternate 

 above, nearly all sessile, lanceolate, very rough above and pubescent beneath ; 

 heads large, on long peduncles; disk yellowish. Edges of marshes and 

 thickets, Man.-Alta. 



5. H. MazimiliElnus, Schrad. 



Resembling the preceding but smaller, seldom more than 5 ft. high; 

 heads large; rays 15-30,' sometimes more than an inch long; bracts of the 

 involucre long, rigid, spreading; peduncles stout and rough. Dry prairies, 

 Sask. and Alta. 



6. H. Nuttailii, T. and G. 



Stem 1-3 ft. high, usually solitary from fascicled fleshy roots, simple 

 below and branched above; leaves opposite below, alternate above, lance- 

 olate to oblong, hispid but not scabrous; bracts linear, hairy on the margins 

 and the tips often turned outward; peduncles all rising to nearly the same 

 level. Prairies, Man.-Alta. 



