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Woodland sunflower flower stalks tend to be hairier than the stem. The flowerheads are 1.5-3" across with 8-15 ray florets with yellow petals (with a tiny notch at the tip) and over 40 yellow, tubular disc florets with five spreading apical lobes. Flower bracts cup the back of the flowerhead in four series, light green, pointed, hairy along their margins, and typically recurved. Only the disc florets are fertile; the ray florets are sterile. Woodland sunflowers can be recognized by their nearly-sessile or sessile, opposite, leaves and broad leaf bases.

Helianthus

Helianthus divaricatus

woodland sunflower [Blooms: Jul-Oct]

Western sunflower is a spindly plant that leads a double life. It is a perennial that first produces a very large (1.5' across) basal rosette of leaves; that basal rosette in turn produces a 2-4' tall, nearly leafless, stem. Clusters (a panicle) of 1-4+ flowerheads are present on pedicels less than 6" long emerging from the stem or upper leaf axils. The flowerheads are 1.5-2.5" across, with 8-20 ray florets, each bearing oblong yellow petals, and over 50 tubular, yellow disc florets with five lobes on their tips and five protruding brown anthers fused around a yellow style with a bifurcated stigma. Only the disc florets are fertile; the ray florets are sterile. (True throughout the genus Helianthus, although that seems more understandable (to me) than the situation in the genus Silphium, where the opposite is true.) Behind the flowerhead are 20-25 lance-shaped bracts (phyllaries) 5-7 mm long with pointed, green or straw-colored tips; there are often hairs round the margins of the phyllaries. The long, sparsely-leaved stem is diagnostic.

Helianthus

Helianthus occidentalis

western sunflower [Blooms: Aug-Sep]