Cardamine species - Bitter-cresses and Cuckooflower

This is a common group of flowers. Two are similar and cause even experienced botanists a few problems.

Cardamine hirsuta, Hairy Bitter-cress, is common in bare dry sunny places, most noticeable in Spring. Can sometimes occur in more moist and shady spots, when liable to be mistaken for C. flexuosa at first glance. It is a low plant, under 30 cm high. Flower diameter c 2-3.5 mm

The stem arises from basal rosette of leaves that have about 5-7 roundish, sometimes stalked, leaflets on each side and a larger one at the end. Stem leaves similar but smaller and fewer, normally no more than 4 per stem, often with narrower leaflets. Usually 4 stamens to a flower (examine several). The similar C. flexuosa has 6, and so does the much larger C. pratensis.

Young pods noticeably overtop the unopened flowers. In C. flexuosa they may not do so at all, or if so, then not in such a pronounced and consistent way. Stems usually hairless.

Cardamine flexuosa Wavy Bitter-cress, is very common in damp shady places, either on bare ground or among other vegetation. A low but upright plant, normally well under 30 cm high but taller in marshes. Flowers c 2.5-4 mm across. Ripe pod c 12-25 mm long.

The stem arises from basal rosette of leaves that have about 5 roundish stalked leaflets on each side and a larger one at the end. Stem leaves similar but smaller and often with narrower leaflets. In C. hirsuta the leaves are mainly in the basal rosette with a straighter stem, whereas C. flexusa has more stem leaves on a wavy stem with a less significant basal rosette. Flowers (examine several) normally have 6 stamens, of which 2 may or may not be smaller than the others. Remember “sexy-flex” sex = six in Latin..

Differentiating C. flexosa and hirsuta can be challenging. Further help here.

Distinguished from C. pratensis by smaller size of all parts and by petals being narrow and separate.

The stems are slightly flexuous and it is usually perennial (C. hirsuta is annual). Flowers always white and stems normally hairy but not always.

Cardamine pratensis, Cuckooflower, is common in damp ground, ditches, fields, beside burns and lochs, and in moorland flushes at all altitudes, flowering in spring and early summer. Flower diameter c 12-21 mm

Lower leaves have roundish stalked leaflets, the end one much the largest. Upper leaves have linear leaflets. Petals are roundish and overlapping and can be mauve or white. Anthers are yellow and there are 6 stamens.

Cardamine amara, Large Bitter-cress, is the least common and is easily distinguished as it is larger in all parts and has violet anthers.