FLORA OF THE DISTRICT OF COLUMBIA. 287 



Plants perennial; leaves mostly opposite; disk 2 cm. wide or smaller. 

 Leaves mostly crowded near the base of the stem, the upper ones distant and 

 much reduced. Leaves ovate to lance-ovate, thick and firm, finely 

 toothed, glabrous or nearly so; bracts shorter than the disk flowers, acute 

 or acutish, finely hairy on the margin, usually glabrous on the outer face. 



5. H. dowellianus. 

 Leaves evenly distributed along the stems, the upper ones not much smaller 

 than the lower. 

 Stems glabrous except about the inflorescence. 



Leaves pale beneath, soft to the touch, finely hairy, lanceolate or oblong- 

 lanceolate, obscurely and finely toothed or entire; bracts about as long 



as the disk flowers 6. H. strumosus. 



Leaves green on both sides, tough-hairy beneath, ovate or lance-ovate, 

 conspicuously toothed; bracts much longer than the disk flowers. 



7. H. decapetalus. 

 Stems copiously hairy throughout. 



Leaves not 3-nerved, lanceolate, short-petioled, mostly alternate. 



8. H. giganteus. 



Leaves 3-nerved, ovate, long-petioled, mostly opposite 9. H. tuberosus. 



1. Helianthus angustifolius L. Swamp sunflower. 

 Wet ground; northeast of Washington, Sept.-Oct. Eastern U. S. 



2. Helianthus divaricatus L. 



Woods and open fields; common. July-Sept. Eastern N. Amer. 



3. Helianthus mollis Lam. 



Open fields near Cabin John, Riverdale, and Hunting Creek; perhaps ad ventive . 

 Aug.-Sept. Eastern U. S. 



4. Helianthus annuus L. Common sunflower. 

 Waste ground about Washington; infrequent. Aug. Native of the western U. S.; 



frequently escaped from cultivation or ad ventive eastward. 



5. Helianthus dowellianus M. A. Curtis. 



Dry hillsides; Little Falls, High Island, and Rock Creek Park. Aug.-Sept. Md. 

 to Ga. {H. occidentalis dowellianus Torr. & Gray; E. occidentalis of Ward's Flora.) 



6. Helianthus strumosus L. 



Woods; frequent. Sept. Eastern U. S. 



Helianthus strumosus mollis Torr. & Gray is a form with the leaves more pubescent 

 beneath. 



7. Helianthus decapetalus L. 



Damp woods; common. July-Oct. Eastern N. Amer. 



* 



8. Helianthus giganteus L. 



Wet groimd; frequent. Sept.-Oct. Eastern N. Amer., west to Colo. 



9. Helianthus tuberosus L. Jerusalem artichoke. 

 Low ground or marshes; frequent along the Potomac. Sept.-Oct. Eastern N. 



Amer. (ff. (/oromcowZes of Ward's Flora.) * 



The Jerusalem artichoke, the tubers of which are used for food, is derived from 

 this plant. 



31. RIDAN Adans. 



1. Bidan altemifolius (L.) Britton. Yellow iron-weed. 



Damp or wet woods; frequent. Aug.-Oct. Eastern U. S. {Verbesina altemifolia 

 Britton; Actinomeris sqitarrosa Nutt.; A. altemifolia DC.) 



A tall coarse perennial with medium-sized heads of yellow flowers having 2 to 8 

 small unequal yellow rays. 



