Coefficient of Conservatism:
Coefficient of Wetness:
THIN-LEAVED SUNFLOWER, PALE SUNFLOWER
Widespread in beech, maple, and red oak forests, especially at borders and openings; also river banks and floodplain forests.
The leaves tend to be thinner in texture than the thick ones of H. strumosus, but that is a comparative and qualitative character unsuited for a key. The petioles in both these species may be as short as 7 mm, but in H. decapetalus they can be as long as 35 mm; in H. strumosus they do not, in our material, exceed 13 (or very rarely 15) mm.
Specimens of Heliopsis helianthoides are occasionally misidentified as this species, for there is some similarity in leaf shape and general pubescence characters. In Heliopsis the outer phyllaries are rounded or only somewhat acute, and the ray flowers are fertile, whereas in Helianthus decapetalus the phyllaries are prolonged-acuminate and (as in other species of Helianthus) the ray flowers are sterile.