Scientific name: Rorippa microphylla (Boenn.) Hyl. ex A. & D. Love
Common name: Narrow-fruited Water-cress
Description
Habit: A hairless perennial, to 1 m high.
Stems: Trailing to ascending or floating when in water, branched but weak.
Leaves: Alternate, pinnate, with oval leaflets.
Flowers: White, actinomorphic, 6 mm across, in racemes; sepals 4, free, 1-1.5 mm; petals 4, free, 1-1.5 mm; stamens dehiscing outwardly; ovary superior.
Fruits: A silique, cylindrical, oblong, 18-25 x 2 mm, with a long, often stout style; the seeds arranged in a single row in the fruit, covered with a network of indentations with more than 12 depressions across the width.
Rorippa x sterilis, a hybrid between Rorippa microphylla and R. nasturtium-aquaticum, is commonly found with the two parent species and occasionally in the absence of either. The fruits of R. x sterilis have at most, 3 well-formed seeds in each fruit, the remainder of the fruit sterile.
Habitat: Marshes, ditches, streamsides, pools, turloughs.
Distribution: Occasional to frequent.
Native status: Native
Of conservation interest: No