Not to be semantically confused with :
Winter Cress (Rorippa × sterilis) [an edible commercially-produced white-flowered cress 50cm tall with similar name]
Compared to Winter-cress which is up to 1m high, with flowers 7-9mm across, fruits (0.7) 1.5 - 3.2cm long, style (1.7)2mm - 3.5 (4mm long, and with basal leaves where the lateral leaflets are about the same width as the terminal lobe, Winter-cress is easily mistaken for :
(Common) Winter-cress is probably the only native plant amongst these Winter-cresses.
- American Winter-cress (Barbarea verna) but this has the largest flowers (7-10mm across) and more than one fruit >4cm long
Medium-flowered Winter-cress (Barbarea intermedia) but this has smaller flowers at 5-7mm across, is a shorter plant at up to 60cm tall, and fruit 1.5-4cm long and style 0.6-1.7mm long.
Small-flowered Winter-cress (Barbarea stricta) but this has the smallest flowers at 5-6mm across, is just as tall as Winter-cress at up to 100cm tall, and fruit smaller still at 1.3-2.8cm long and style 05 - 1.8 (2.3)mm long. A distinguishing feature is that the basal leaves have a much wider terminal lobe than the other lateral leaflets on it.
Some similarities to : Charlock (Sinapis arvensis) but that is branched and bushy (rather than upright and narrow) and the leaves are usually bristly and have un-even teeth and with just a couple of opposite lobes nearest the stem.
No relation to : Winter-greens such as Common Wintergreen (Pyrola minor), Winter Aconite (Eranthis hyemalis),
Winter Jasmine (Jasminum nudiflorum) nor to Winter Heliotrope (Petasites fragrans) [plants with similar names belonging to a different family].
It is found on dampish ground near hedges, roadsides, waste places and streamsides throughout most of the UK. The flowers have six stamens with yellow anthers and the pods have a long style at the end (rather than a beak). It is very variable in features such as leaf shape, pod size, and is generally regarded as highly polymorphic, even more so on the Continent.