This grower is sure of this plant identification.
Watercress is an aquatic leafy green vegetable that grows wild in shallow waterways, ponds, streams and natural springs. ... As a nutrient-rich wild food source, it has been utilized for its nutritious leafy stems as both a raw vegetable and steamed green.
Watercress, Common watercress
Nasturtium officinale (Watercress). This species has creeping stems which are about 75cm in length. The flowers are small and white which appear in racemes. This plant is often found in the wild in Northern Europe. STEM: Low-growing, turning upright, rooting, hollow. ROOT: Branched, creeping stock. HAIRS: Absent STIPULES: Absent LEAF-STALK: Present or absent above. BRACTS: Absent FLOWER STALK: 0.8-1.2cm SEPALS: 4, alternating with petals. PETALS: 4, equal, rounded with stalk-like base. STAMENS: 6 STIGMA: 1, sometimes 2-lobed. OVARY: 1, 2-celled SEEDS: Many, egg-shaped, shallowly pitted.
They grow well in damp, shaded corners of the garden as well as in ponds. You can plant from cuttings or seed.
Wildflower/meadow, culinary, semi-aquatic.