Annual Sunflower, Common Sunflower

(Helianthus annuus L.)

Asteraceae (Aster Family)

▲ young plant

▲ ▼ mature flowering plants

▲ flower

Annual Sunflower, Common Sunflower: (pp.142-143, Weeds of the Great Plains; mentioned on pp. 146-147, Weeds of the Northeast)

·        native, summer annual flower in Aster family

·        typical "sunflower" flowers, large rough heart-shaped to triangular leaves

·        usually much branched plant with more, but smaller flowers than cultivated sunflowers

·        grows 4-10' tall

·        allelopathic to itself (autotoxic) and other plants for several years after initial planting

·        spreads rapidly by seed in cultivated fields, prairies, pastures, waste areas

·        not often in strong competition with crops, but allelopathic nature may make it undesirable in fallow field, where it can be a strong presence

In western midwest states, becomes interspersed with Prairie Sunflower, which has longer flowering stalks, and slightly smaller and more shiny leaves than annual sunflower.