Minnesota Dwarf Trout Lily
Minnesota Dwarf Trout Lily
|Listed||March 26, 1986|
|Description||Perennial with one pair of pointed leaves and a nodding, bell-shaped, roseate flower.|
|Habitat||Mature deciduous forests along rivers.|
|Threats||Conversion of land for agriculture, road construction, urbanization, and collectors.|
The Minnesota dwarf trout lily (Erythronium prop-ullans; sometimes referred to as the prairie trout lily) is a spring ephemeral that grows as a single pair of mottled-green pointed leaves. The leaves are parallel veined and arise from near the base of the stem to a height of about 6 in (15.2 cm). In April or May the plant puts up a slender flowerstalk, tipped by a single nodding, bell-shaped, pink or roseate flower with recurved petals. Flower parts number four or five, rather than six as in other species of Erythronium, and are generally smaller than those of the white trout lily (Erythronium albidum ). Fruits are nodding when mature rather than erect.
In June, when the tree canopy fills in, the upper parts of the plant wither. The Minnesota dwarf trout lily reproduces vegetatively by sending out lateral shoots to establish new clones. Reproduction by seed occurs infrequently. Renewal of the parent bulb and formation of the offshoot bulb both take place during the brief period of photosynthetic activity before the leaves wither.
The Minnesota dwarf trout lily is found along wooded river valleys, where it roots in loamy, alluvial soils. It grows mostly on the lower parts of north-facing slopes that rise up to 90 ft (27.4 m) above the stream beds. The species prefers areas of moderate to heavy shade, where it grows in dense colonies that sometimes spread onto the flood plain. It is usually associated with other ephemerals such as Dutchman's breeches, white dog-tooth violet, and snow trillium.
Discovered near St. Mary's College at Faribault (Rice County) in 1870, the Minnesota dwarf trout lily is considered endemic to southeastern Minnesota. It grows along the Cannon, Straight, and Zumbro Rivers (Rice and Goodhue Counties) in the region directly south of Minneapolis and St. Paul.
In 1986 this species was thought to be represented by 17 localities in Rice County and by two sites in Goodhue County, totaling no more than about 8,000 individuals. Most sites are privately owned. In 1991 three additional trout lily colonies were discovered on a farm near Cannon Falls, Minnesota.
Several large historic colonies near the city of Faribault were eliminated when land was converted to agriculture. Road construction destroyed a number of other sites, and various effects of ongoing urban development are considered a threat to remaining populations.
Wildflower collectors, who thoughtlessly pick flowers at the more accessible sites, pose a significant threat. And even institutional collectors make mistakes: one site was severely damaged in the early 1970s when large numbers of plants were removed and replanted in a university landscape arboretum. With its inefficient means of vegetative, rather than sexual, reproduction, the plant is slow to recover when disturbed.
Conservation and Recovery
This trout lily is listed as endangered by the state of Minnesota and afforded limited protection by a state law that prohibits taking, transporting, and selling endangered and threatened plants from all lands except ditches, roadways, and certain types of agricultural and forest lands. This law does not prohibit the loss and disturbance of habitat, which is the primary concern.
Four sites have been purchased and are managed by the Nature Conservancy and a cooperating group, the Riverbend Nature Center. These sites include the Trout-Lily Preserve (Rice County) and the Grace Nature Preserve (Goodhue County). Even protected populations could be damaged if adjacent forestlands are intensively logged or cleared for cropland or for housing.
In addition, some private landowners are engaged in protective action. A case in point: Schluter's Woods, a 40-acre (16-hectare) farm near Cannon Falls, Minnesota, owned by Paul and Rosie Schluter. They became voluntary caretakers of this endangered wildflower on their maple-basswood, flood plain forestland when the species was discovered there in 1991.
The Schluters are aware of the scientific significance of the find and are comfortable with the responsibility that goes along with being the owners and managers of such a rare and fragile species; they view the presence of such a rare species on their land as a privilege.
Banks, J. 1980. "The Reproductive Biology of Erythronium propullans Gray and Sympatric Populations of E. albidum Nutt. (Liliaceae)." Bulletin of the Torrey Botanical Club 107: 181-188.
Johnson, A. G., and M. K. Smithberg. 1968. "A Wild-flower Unique to Minnesota." Minnesota Horticulturalist 96: 38-39.
Meuller, L. May/June 1995. "Lilies in Schluter's Woods." Endangered Species Technical Bulletin 20 (3).
Morley, T. 1978. "Distribution and Rarity of Erythronium propullans in Minnesota, with Comments on Certain Distinguishing Features." Phytologia 40: 381-389.
Morley, T. 1982. "Flowering Frequency and Vegetative Reproduction in Erythronium albidum and E. propullans, and Related Observations." Bulletin of the Torrey Botanical Club 109: 169-176.