Growing on the edge of the grass path at the lower (wet) part of my allotment is this plant, another member of the Brassicaceae, the Crucifer family with flowers typically having 4 petals in a cross shape. Like the Arabidopsis this has small white flowers and long seed capsules called siliqua. It also has a basal rosette of leaves but the leaves of Cardamine are pinnate, not simple. As shown in the sketch above the stem has long pointed and shorter glandular hairs. There are also curved pointed hairs on the upper side of the leaves (this is the same as the Ross-Craig illustration; plate 22). The flowers have one disc shaped stigma and 6 stamens. The back of the calyx has 1 or 2 projecting long hairs.
Now there are 2 plants which are very close, Cardamine flexuosa and Cardamine hirsuta. C flexuosa generally has 6 stamens with flowers overtopping fruit, C hirsuta generally has 4 stamens with fruit overtopping flowers. As this is an end of season plant there was only a couple of flowers on it so the only guide is the number of stamens (6) so its probably C flexuosa.