Mistflower (creeping crofton weed)
Ageratina riparia (Eupatorium riparium)

Erect, sometimes decumbent herb, 0.3–1 m tall; stems purplish, spreading prostrate in lower parts, rooting at nodes, ± non-glandular hairy.

Leaves lanceolate or narrow-ovate, 3–12 cm long, 8–30 mm wide, apex acuminate, base tapered, lamina glabrous or slightly hairy on veins, prominently veined; petiole to 1.5 cm long.

Heads 5–6 mm diam., crowded in corymbs; involucral bracts oblong-lanceolate, 2-seriate, ± equal, hairy, striate, green to purplish. Florets white.

Achenes 1–2 mm long; hairy, ± only on ribs; pappus bristles 3–4 mm long, barbellate.