Plant · P-115

Watercress

Nasturtium officinale

Watercress is a fast-growing aquatic green harvested for its peppery, vitamin-rich leaves, best treated as a spring and autumn crop since warm water above about 75 F turns it bitter and slows growth. It roots wherever a stem touches wet ground, which makes it easy to grow in a contained tank or trough but risky to let escape into a creek or pond, where a single broken-off node can start a new colony. Wild or stream-gathered cress should always be cooked, never eaten raw, because water draining from grazing land can carry a liver-fluke parasite that only cooking destroys.