P. hydropiper hydropiper P. hydropiper
Perianth dotted with prominent glands, green whitish or reddish. Flowers rather distant or interrupted, in slender drooping spikes up to 10 cm long. Leaves 3–9 cm long. Weak herb up to 1 m high. Widespread. Wet places. Possibly introd. from Europe. Fl. summer. Water Pepper or Water Smartweed