1906 Why the Dwarf Trout Lily Is Hard to Find - webapps8

Why theDwarf Trout LilyIs Hardto FindI The tiny flower of the dwarf trout lily opens completely for just a few hours.36 THE MINNESOTA VOLUNTEER

The dwarf trout lily occursnaturally in Minnesota andnowhere else in the world.Survival of this rarewildflower is in questionON A SPRING day in 1870, MaryHedges, a botany teacher at St.Mary's School in Faribault, Minn.,came upon an unusual, diminutive lilygrowing on the banks of the StraightRiver. A specimen was sent to AsaGray, a botanist at Harvard University,who determined that it was a newspecies and named it Erythroniumpropullans. The tiny wildflowerbecame more commonly known as thedwarf trout lily, Minnesota trout lily,or dwarf dog-toothed violet.Since it was first discovered, manybotanists have searched for other siteswhere the dwarf trout lily might grow.It has been found in only two countiesin southeastern Minnesota and hasnever been found outside the state.In fact, it is Minnesota's only endemicwildflower—one that occurs naturallyhere and nowhere else.All known locations of dwarf troutlily arc found within a 275-square-milearea in Rice and Goodhue counties.Within this small area, roughly 600acres are suitable habitat for this troutlily.The lily most often grows on rich,Ellen Fugewell-aerated soil on wooded, northfacingslopes and on flood plains alongstreams or old stream channels. Amere 75 acres of this habitat areactually populated by this fragileflower. Because of its limited rangeDNR botanist Welby Smith examinesdwarf trout lilies growing in rich soil onwooded slope in one of few knownlocations of Minnesota's rare lilies.MARCH-APRIL 1989 37

Rare Wildflowerand small numbers, the dwarf troutlily was given endangered speciesstatus by the state of Minnesota in1984 and by the federal governmentin 1986.Habitat destruction is the greatestthreat to survival of the dwarf troutlily. Road construction, certain recreationalactivities, urban expansion,logging, and some agricultural practicesmay destroy or increase erosionand siltation of trout lily habitat.We are gradually learning moreabout this rare flower. The dwarf troutlily is one of many spring ephemerals—plantsthat complete their entirelife cycle during a few weeks in spring.This short cycle is an adaptation toliving in deciduous forests—typicallysugar maple, basswood, cottonwood,and soft maple—where plantson the forest floor must grow, flower,and set seed before leaves form ontrees and block sunlight. Otherephemerals sharing the forest floorwith the dwarf trout lily include Virginiawaterleaf, cleavers, springbeauty, and the common white troutlily.Look-Alikes. The dwarf trout lilyand the white trout lily look much likeeach other. They can best be distinguishedfrom each other when inflower. The flowers of the dwarf troutlily are smaller and pinker.Ellen Fuge is natural resource specialist,Natural Heritage Program, DNR Sectionof Wildlife, St. Paul.Fruits of the dwarf trout lily are alsosmaller and nod slightly on their stem.Fruits of the white trout lily areupright. The leaves of these two similarspecies are about the same sizeand slightly mottled, but those of thedwarf trout lily tend to be narrowerand taper more gradually toward thetip.Although the dwarf trout lily has arestricted range, it is typically foundwith the white trout lily, which isbroadly distributed. It has never beenfound with the yellow trout lily, alsofound in Minnesota.The dwarf trout lily may haveevolved from the white trout lily nomore than 9,000 years ago, after thelast glaciers left Minnesota. A recentstudy by John Pleasants, botany professorat Iowa State University,showed that the dwarf trout lily has agenetic makeup similar to that of thewhite trout lily. The two trout liliesare able to crossbreed, producing ahybrid with intermediate physicalcharacteristics.Pleasants demonstrated that largepopulations of dwarf trout lilies arecomposed of genetically identicalindividuals or clones. This confirmedthat the predominant, and perhapsonly, means of reproduction in thedwarf trout lily is from runner bulbs.Pleasants identified only 21 genotypesof dwarf trout lily, illustratinglittle genetic diversity compared tothat of the white trout lily and manyother flowering plants that reproducethrough seed production. However,this limited number of genetic38 THE MINNESOTA VOLUNTEER

As part of the DNR Natural Heritage Program's endangered species project, DNRworkers and volunteers map and take a census of dwarf trout lily populations.types of dwarf trout lily demonstratesthat at some time in the past geneticdiversity was achieved through seedproduction.Unusual Reproduction. The dwarftrout lily has several other characteristicsthat set it apart from other troutlilies and help explain why it is sucha rare and geographically restrictedplant. Unlike many flowering plants,the dwarf trout lily produces seedinfrequently, if at all.With support from the Minnesotachapter of the Nature Conservancy,JoAnne Banks, a graduate studentfrom La Crosse, Wis., spent twoseasons observing these plants forpollinators. The minor bee was themost frequent pollinator observedMARCH-APRIL 1989 39

DNR botanists visit dwarf trout lily site in Nerstrand Woods State Park eachspring to observe variations and patterns in the number of plants flowering.many plants bloomed the second year.This was a pleasant surprise, indicatingthe presence of more plants thanbotanists originally thought.Botanists will return to this site forseveral years to look for any variationor pattern in the number of plants thatflower each spring. From this researchthey hope to learn if fluctuations inpopulations are natural phenomenonor indications of disturbances requiringmanagement action.The DNR Scientific and NaturalAreas Program assists the park inmanaging the Nerstrand Woods site.Rip-rap constructed on the banks ofa stream adjacent to the site reduceserosion, which threatened the lilypopulation. A boardwalk allows visitorsto view the lilies without tramplingthem.Research to develop an alternatemeans of propagation for the dwarftrout lily has been proposed by theHolden Arboretum in Cleveland,Ohio. The Holden Arboretum is amember of the Center for Plant Conservation,a private Massachusettsbasedfoundation promoting preservationof endangered plants.Using funds raised by the MinnetonkaGarden Club, the Center hopesto find ways to increase the numberof individual plants. These efforts willenhance the relatively slow rate ofreproduction in the wild and aid inmanagement and restoration of thisrare species. •MARCH-APRIL 1989 41