Cardamine pratensis is a glabrous perennial herb in the mustard family (Brassicaceae) with four-petalled purple-pink or white flowers and irregular pinnate leaves with small, ovate segments. Commonly found in shrublands, riverbanks or moist rocky slopes and meadows, it grows from short rhizome, reaching up to 30 cm tall in flower. The basal leaves are arranged in a rosette, and are pinnate with 9-17 orbicular to lanceolate leaflets. The stem leaves have leaflets that are linear to oblanceolate. The basal leaves are usually shed early in the season. Both stems and leaves lack hairs. The inflorescence is a simpleraceme with pink to perfect flowers with four petals 8-15 mm long. The flowers are usually all at the same height due to longer pedicels on the lower flowers. The siliques (narrow seedpods) are erect, up to 3 cm long and glabrous. Cuckoo flower is distinguished from the other species of Cardamine in the park by its large flowers (petals longer than 4 mm) and glabrous stems. The common name 'cuckoo flower' may derive from the extremely variable, or 'crazy' basal leaves (Aiken et al. 2011), or, the name may come from its flowering at the same time that the Cuckoo bird begins singing in Europe (Devlin 2015).
Cardamine pratensis flowers from April through July. The seeds are dispersed throughout the spring and summer.
Cardamine pratensis is monoecious and insect pollinated, but flowers cannot self-pollinate (Salisbury 1965). When outcrossed, Cardamine pratensis reproduces by seeds. When seeds are produced they are dispersed by the explosive mechanism of the drying fruit valves and then by wind. More commonly, this plant spreads by vegetative means, such as by rhizomes, stolons and leaflets. The leaflets function as small bulbils and are dispersed by water and birds foraging in wetlands (Flora of Svalbard 2016).
Cardamine pratensis is host to twenty documented insect species: one mite, four leaf beetles, six weevils, two gall midges, one shield bug, three butterflies, one moth, one ermine moth, and the meadow froghopper, Philaenus spumarius whose larvae form blobs which are called 'cuckoo spit' (Biological Records Centre 2008, O'Reilly 2015). Albugo candida, a water mold and plant pathogen, infects the leaves, stems, flowers, fruits and seeds of Cardamine pratensis. Peronospora parasitica is a mildew which infects the leaves and stems. Ramularia cardamines creates spots on its leaves. (Peat et al. 2015).
Cardamine pratensis is a widespread circumpolar species occurring in boreal and arctic regions across the northern hemisphere. Similarly, this species occurs scattered in suitable habitats across Alaska generally and also Denali, but is usually not abundant.
Cardamine pratensis occurs at lower elevations in the park when compared to the other three species of the genus. It is found at 89 m-1244 m and an average of 677 m. It occurs more frequently on north-facing slopes (25 out of 40 occurrences) than on south-facing slopes, and at a wider range of altitudes on north-facing slopes (89-1244 m) as compared to south-facing slopes (211-1100 m). It occurs most often on relatively flat terrain, i.e. less than 5 degrees (26 out 40 occurrences). Otherwise, it is found on north-facing slopes up to 22 degrees and on south-facing slopes up to 18 degrees.
Cardamine pratensis grows in mesic, very moist, wet or submerged sites often in moss carpets or in open wet gravel or sand. It is found in wet meadows, poorly drained areas, seepage slopes, and marshes and along streams. It is most often found in soils with high organic content, and in peaty, non-calcareous soils (Aiken et al. 2011).