Re-introductions of an increasingly rare North American lily to prevent regional extinction

Summary

Lilium canadense subsp. michiganense, the Michigan lily, has nearly vanished from the tallgrass prairie, which has itself declined 99.9% over 200 years, leaving the species endangered in New York and threatened in Tennessee, with only small, isolated populations elsewhere and no viable seed production observed in the wild. Since 1992, the Grewcock Center for Conservation Research at Omaha's Henry Doorly Zoo has run a long-term propagation program, beginning by collecting tissue samples, rather than whole plants, from four sites in Nebraska and one in Iowa to avoid unintended pollen transfer, since no seed was available for the species. These tissues have been continuously cloned in vitro, hardened off, and planted into protected, permanently uncultivated prairie sites near their source populations, in partnership with organizations including the Audubon Society, the Nature Conservancy, the US Fish and Wildlife Service, and Nebraska's Statewide Arboretum, which distributes propagules to private landowners. Annual monitoring by zoo scientists and land managers tracks survival, growth and flowering, which typically begins only after three growing seasons; rodent predation on newly planted bulbs has been managed with coarse gravel or wire cages, and one site was lost to Missouri River flooding in 2012 while all others have persisted, including the first site planted in 1993, which still supports lilies after more than 20 years. The species proved capable of vegetative spread via underground stolons once established, though it resents disturbance and may not reappear after excavation. The project rates itself successful, citing highly effective tissue-culture propagation, careful site selection, and reliable vegetative colony formation at most planted sites.