Dickinson County, Iowa, Fen orchids, Orchidaceae, Silver Lake Fen, Species Biology
The native orchids Liparis loeselii and Spiranthes romanzoffiana inhabit hydric-mesic sapric histosol soils supporting three distinct fen vegetation zones at Silver Lake Fen State Preserve. Platanthera hyperborea and Cypripedium candidum primarily inhabit adjacent mesichydric aquoll mollisols supporting wetland and marsh vegetation. The fen orchids possessed shallow subterranean storage organs and perennating buds bathed in shallow water, while the non-fen orchids exhibited deep storage organs and perennating buds above a deep water table. Ramet census demonstrated all orchids possessed reproductive efforts greater than 90%, except C. candidum which exhibited 52% effort, probably due to low pollination. Genet analyses suggest L. loeselii and S. romanzoffiana total 267 and 22 individuals respectively, while C. candidum and P. hyperborea respectively total 666 and 2797. The fen orchid populations are smaller, but the larger non-fen species populations may be declining due to encroachment and competition from Fraxinus, Typha and Phragmites.
Proceedings of the Iowa Academy of Science
©1984 Iowa Academy of Science, Inc.
Carroll, Sara; Miller, Robert L.; and Whitson, Paul D.
"Status of Four Orchid Species at Silver Lake Fen Complex,"
Proceedings of the Iowa Academy of Science, 91(4), 132-139.
Available at: https://scholarworks.uni.edu/pias/vol91/iss4/5