Differs from
Nasturtium officinale R. Br. only by its narrow, linear fruit and seed characters as mentioned in the key. This has 2n=64 (while
Nasturtium officinale has 2n=32), apparently an allotetraploid of
Nasturtium officinale.
Leaves and stem turn purplish in autumn. Siliquae 15-22 mm long, usually 1 mm broad., slender on up to 20 mm long pedicels, spreading; valves smooth glabrous; seeds uniseriate, c. 0.8 mm long, with c. 100 polygonal depressions on each face.