Rydberg’s sunflower

Helianthus rydbergii Britton, Man. Fl. N. States, 993. 1901

Plants usually 100–250 cm. Leaves all or mostly opposite; blades lanceolate to nearly ovate, apices acute to obtuse, abaxial faces hispid to hispidulous. Phyllaries: abaxial faces ± glabrate or sparsely hairy (longer hairs 0.5–1 mm).

Flowering late summer–fall. Open areas, sandy dry soils, wet places; 200–1000 m; Alta., Man., Ont., Que., Sask.; Colo., Iowa, Minn., Mont., Nebr., N.Dak., S.Dak.