Rare Species Guide

  Basis for Listing

Floerkea proserpinacoides (false mermaid) has discontinuous ranges in the eastern and western United States that are separated by the Great Plains. This species occurs in Minnesota at the very northwestern edge of its eastern range. An inconspicuous spring ephemeral with a very short growing season, F. proserpinacoides occurs in cold, spring-fed seeps in southeastern (Paleozoic Plateau and Minnesota and Northeast Iowa Morainal sections) and east-central (Western Superior Uplands Section) counties. This sensitive habitat type is dependent on groundwater input that could be adversely influenced by activities that disrupt or contaminate the aquifer. This is a real threat, even if the disruption occurs some distance from the plants. Floerkea proserpinacoides was originally listed as a special concern species in Minnesota 1984, but given the loss of much of its preferred habitat and a better understanding of the threats it faces, it was reclassified as threatened in 1996.

  Description

Floerkea proserpinacoides plants are a distinctive lime green color. They have weak decumbent stems with alternate leaves that are deeply divided into 3-7 linear, oblanceolate or narrowly elliptic lobes, each 1-2 cm (0.4-0.8 in.) long. Peduncles are borne from the upper axils, initially equal to the length of the petiole but becoming much longer in fruit. Tiny white flowers are regular, perfect, hypogynous, and 3- to 5-merous. Sepals and petals are free and distinct. Fruits are deeply divided, separating at maturity into indehiscent segments (Gleason and Cronquist 1991).

  Habitat

Floerkea proserpinacoides occurs primarily in seepage areas along wooded hillsides and in narrow valleys and secondarily in ephemerally moist areas and low drainages in deciduous forests. This fairly uncommon and localized habitat is largely confined to a few southeastern and east-central counties in Minnesota. Some populations extend from the seep into adjacent seepage swamps, which are often dominated by Fraxinus nigra (black ash), Tilia americana (basswood), and Ulmus americana (American elm), with Caltha palustris (common marsh marigold) and the rare Carex laevivaginata (smooth-sheathed sedge).

  Biology / Life History

Floerkea proserpinacoides is especially unusual in that it is both a spring ephemeral and an annual. Although only a few populations of this species are known in Minnesota, some consist of thousands of plants and form rather dense patches. Some smaller populations may have distinct boundaries, are round or elliptical in shape, and appear to be clones. The populations adjacent to Mille Lacs Lake in central Minnesota occur across an extensive area.

  Conservation / Management

Floerkea proserpinacoides is an inconspicuous spring ephemeral with a very short growing season, so searches of suitable habitats in early spring may yield new discoveries. However, it is known that this species' habitat is dependent on groundwater input that could be adversely influenced by remote activities that disturb or contaminate the source of water. Soil disturbance and tree canopy removal (even removing a portion of the canopy) may have an adverse impact on this species. The presence of the invasive, non-native plant Nasturtium officinale (watercress) may pose a threat to some populations. Several populations have been damaged by off-highway vehicle activity.

  Best Time to Search

In southeast Minnesota, this spring ephemeral is only visible from early to mid-May, possibly early June in east-central Minnesota. Floerkea proserpinacoides completes its flowering and fruiting stages in a period of 2-3 weeks, so searches must be highly focused during that window of time.

  Conservation Efforts in Minnesota

Several F. proserpinacoides populations occur in State Forests, State Parks, and state Wildlife Management Areas. These public lands are fairly well protected from most development threats and from livestock grazing, but known locations require management plans that maintain the habitat and restrict off-highway vehicle access.

  Authors/Revisions

Welby R. Smith (MNDNR), 2021

(Note: all content ©MNDNR)

  References and Additional Information

Gleason, H. A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. Second Edition. New York Botanical Garden, Bronx, New York. 910 pp.

Minnesota County Biological Survey. 1994. Natural communities and rare species of Houston County. Minnesota County Biological Survey Biological Report No. 50. Minnesota Department of Natural Resources, St. Paul.

Minnesota County Biological Survey. 1994. Natural communities and rare species of Winona County. Minnesota County Biological Survey Biological Report No. 49. Minnesota Department of Natural Resources. St. Paul.

Ownbey, G. B., and T. Morley. 1991. Vascular plants of Minnesota: a checklist and atlas. University of Minnesota Press, Minneapolis. 320 pp.

Smith, B. H. 1983. Demography of Floerkea proserpinacoides, a forest-floor annual. Journal of Ecology 71:405-412.

Wovcha, D. S., B. C. Delaney, and G. E. Nordquist. 1995. Minnesota's St. Croix River Valley and Anoka Sandplain:a guide to native habitats. University of Minnesota Press, Minneapolis. 248 pp.