Rare Species Guide

  Synonyms

Cardamine pratensis var. palustris

  Basis for Listing

Cardamine pratensis (cuckoo flower) is found in several of Minnesota's northern counties (Laurentian Mixed Forest Province), where there are still functional habitat complexes. Even though potential habitat may seem expansive, the actual number of occurrences of C. pratensis is quite small. The ecological or biological reasons for this are unknown.  Cardamine pratensis was designated threatened in 2013.

There is some uncertainty as to whether C. pratensis var. palustris is taxonomically distinct from C. pratensis var. pratensis (Al-Shehbaz et al. 2010). However, there is clearly only one variety in Minnesota, so whether it is var. palustris or var. pratensis does not bear directly on the question of its conservation needs within the state.

  Description

Cardamine pratensis is a perennial, with erect and unbranched stems that may reach a height of 55 cm (22 in.). The stems are usually glabrous or occasionally sparsely pilose at the base. The rhizomes are relatively short and produce simple or multifoliate leaves to 30 cm (12 in.) in length, with a petiole 2-7 cm (0.8-2.6 in.) long. The leaflets of the rhizomal leaves are petiolulate or sessile. The blade of the terminal leaflet is orbicular or broadly obovate and 0.3-2.0 cm (0.1-0.8 in.) in diameter. The cauline leaves are pinnately compound and petiolate. There are 4-7 leaflets on each side of the rachis that are either petiolulate or sessile and decurrent; the blade margins are usually entire or rarely dentate. The racemes lack bracts. The fruiting pedicels are erect-ascending or sub-divaricate and 12-25 mm (0.5-1.0 in.) long. The sepals of the flowers are erect or spreading, oblong or ovate, 3-5 mm (0.1-0.2 in.) long; the lateral pair are saccate basally; the petals are usually white, obovate, 8-15 mm (0.3-0.6 in.) long. The fruits are linear in shape and 2.5-4.5 cm (1.0-1.8 in.) long. The seeds are light brown, oblong, and 1.2-1.8 mm (0.05-0.07 in.) long (Al-Shehbaz et al. 2010).

  Habitat

The habitats of C. pratensis in Minnesota fall within the colloquial use of the term “bog”, though ecologists would use the term “fen” or “swamp”. More specifically, it has been found associated with small ponds or pools in sedge-dominated fens and in white cedar swamps. These habitats are permanent wetlands, where the water is weakly acidic to circumneutral and where sunlight is intermittent.

  Biology / Life History

Cardamine pratensis is an insect-pollinated perennial. Although the specific pollinator species or range of species is unknown, the structure of the flower indicates a wide range of flying insects may serve as effective pollinators. Reportedly, the flowers are self-incompatible (Salisbury 1965), meaning that cross-pollination is required to produce viable seeds. The seeds are small and disperse when the seed capsules become ripe and split open, while still attached to the plant. Observations in Minnesota indicate that relatively few plants produce flowers in any given year, most will appear as sterile rosettes of pinnately-compound leaves.

It has been reported (Salisbury 1965) that this species, or a closely related species, in Europe undergoes vegetative reproduction by producing plantlets on leaf surfaces. This process does not involve pollination and is essentially vegetative reproduction. Although the potential of Minnesota plants reproducing in this fashion has not been reported in the literature, it is a possibility that should be studied.

  Conservation / Management

Most of the Minnesota habitats are conifer swamps, some of which have a history of tree cutting (evidenced by scattered stumps). Because so little is known about the ecological requirements of this species, it is difficult to assess what effect this activity has had on populations. A conservative approach would be to establish a reserve where populations are known to occur and a buffer area outside the reserve. The size of the buffer would vary, depending on the position of the population within the landscape. Minimal selection harvesting of trees within the buffer may not adversely affect populations, but any forest management needs to occur in winter to prevent damage to the soil and moss cover and to minimize disruptions in water flow. Slash must be removed subsequent to any management activity in order to maintain the potential microhabitat requirements of this threatened species. A greater threat to habitat integrity is from road construction, beaver activity, or other activities that could disrupt the hydrological system that sustains this habitat.

  Best Time to Search

This species can be recognized when in flower and when in fruit. Suggested search dates are early June through mid-July, with the prime time being the last two weeks of June.

  Authors/Revisions

Welby R. Smith (MNDNR), 2018

(Note: all content ©MNDNR)

  References and Additional Information

Al-Shehbaz, I. A., K. Marhold, and J. Lihova. 2010. Cardamine. Pages 464-484 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 7. Oxford University Press, New York, New York.

Minnesota Department of Natural Resources. 2003. Field guide to the native plant communities of Minnesota: the Laurentian mixed forest province. Ecological Land Classification Program, Minnesota County Biological Survey, and Natural Heritage and Nongame Research Program. Minnesota Department of Natural Resources, St. Paul, Minnesota. 352 pp.

NatureServe. 2009. NatureServe Explorer: An online encyclopedia of life [web application]. Version 7.1. NatureServe, Arlington, Virginia.

Salisbury, E. 1965. The reproduction of Cardamine pratensis L. and Cardamine palustris Peterman particularly in relation to their specialized foliar vivipary, and its deflexion of the constraints of natural selection. Proceedings of the Royal Society of London. Series B, Biological Sciences. 163(992):321-342.

Wisconsin Department of Natural Resources. 2007. Cuckooflower (Cardamine pratensis) factsheet. <http://dnr.wi.gov/topic/endangeredresources/Plants.asp>. Accessed 9 July 2009.