Common waterplantain (European water plantain, great water plantain, mad-dog wee)
Alisma plantago-aquatica

Height: 30–100 cm (12–40 in.).

Flower: Regular (actinomorphic), approx. 1 cm (0.4 in.) wide. Petals 3, separate, white to pale pink. Sepals 3, separate, green, clearly shorter than petals. Stamens 6. Several carpels. Pedicels 1–3 cm (0.4–1.2 in.). Flowers in whorled groups forming a narrowing (cone-like) raceme.

Leaves: Most leaves aerial, floating and submerged leaves fairly common in flowing water. Aerial and floating leaves long-stalked, 8–25 cm (3–10 in.) long. Blade ovate, with rounded or cordate base and entire margins. Submerged leaves may have a strap-shaped blade.