Lysimachia maritima (L.) Galasso, Banfi & Soldano
Basis for Listing
Lysimachia maritima (sea milkwort) is most characteristic of coastal sea marshes, encircling the northern latitudes from Eurasia to North America. It also appears in isolated inland alkaline or saline wetlands. Habitats of this type are quite limited in Minnesota, which explains, in part, why the species is rare here. Recent record describes the plant as being common in one small remnant habitat but absent from similar habitats nearby. Most of the potential wetland habitat in Minnesota is in Kittson County, but some is scattered in three or four other western counties (Red River Prairie Subsection). There has been a general decline in this habitat type throughout the region. The high demand for tillable land has resulted in the drainage of most of the alkaline or saline wetlands for conversion to crop production, in spite of their unsuitability for most agricultural purposes. Lysimachia maritima was originally listed as a special concern species in Minnesota in 1984, but given its extreme rarity, it was reclassified as endangered in 1996.
It is rather difficult to confuse L. maritima with any other species, particularly those found in the same habitat. It is a low succulent perennial herb that spreads by underground stems, often forming carpets on the surface. Its fleshy leaves are short, stalkless, and oblong to narrow. The white, pink, or purple flowers are tucked in the leaf junctions. Lacking petals, it is the 5 sepals that provide color. The fruit is a capsule 2-3 mm (0.08-0.12 in.) across (Great Plains Flora Association 1986).
In Minnesota, the preferred habitat of L. maritima is imperfectly known but probably includes alkaline or saline soil in low meadows, seasonally wet prairies, periodically dry streambeds, and lakeshores. Studies show that this species tolerates high salinity and long periods submerged under water. It prefers moist, sparsely vegetated soil in direct sunlight and has particular moisture requirements; too little or too much moisture restricts its distribution (Brotherson and Barnes 1984; Great Plains Flora Association 1986).
Biology / Life History
Lysimachia maritima does produce seeds, but under stable environmental conditions it reproduces primarily by vegetative means. This happens when small plantlets develop from buds at the nodes of underground rhizomes. The above-ground portions of the plants die back during the fall, but the buds are able to survive the winter. Seeds seem to resist decay and are reported to be viable in the seed bank for 100 years (Hammer and Heseltine 1988). Like most halophytic plant species, L. maritima possesses specialized mechanisms to cope with high concentrations of salt (sodium chloride) in the rooting zone of its habitat. This includes highly unusual salt glands on the leaf surfaces that secrete excess salt which would ordinarily be injurious to plant tissue (Rozema and Riphagen 1977).
Conservation / Management
Lysimachia maritima faces a direct threat from wetland destruction. Wetlands across the Midwestern grain-producing region of the United States have been drained, ditched, filled, and dredged. As wetlands have disappeared, so too have the species that relied on them, including L. maritima. It is critical that wetlands receive protection and that wetland laws be enforced. Light cattle grazing for short periods apparently does little permanent harm to this species, and may, in some cases, favor it by reducing the more palatable competition. But continuous heavy grazing can damage or eliminate populations by trampling and soil compaction.
Best Time to Search
The best time to search for Lysimachia maritima is during the flowering period from mid-June through September.
Conservation Efforts in Minnesota
The Minnesota Biological Survey has inventoried Kittson County and found only one site of L. maritima. However, a considerable amount of potential habitat remains to be searched. Botanists agree that further searches, if highly directed and focused, have a chance of finding this species again.
Welby R. Smith (MNDNR), 2020
(Note: all content ©MNDNR)
References and Additional Information
Brotherson, J. D., and S. J. Barnes. 1984. Habitat relationships of Glaux maritima in central Utah. The Great Basin Naturalist 44(2):299-309.
Cholewa, A. F. 2009. Lysimachia. Pages 308-318 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 8. Oxford University Press, New York, New York.
Hammer, U. T., and J. M. Heseltine. 1988. Aquatic macrophytes in saline lakes of the Canadian prairies. Hydrobiologia 158:101-116.
Jerling, L. 1988. Population dynamics of Glaux maritima (L.) along a distributional cline. Vegetatio 74:161-70.
Rozema, J., and I. Riphagen. 1977. Physiology and ecological relevance of salt secretion by the salt gland of Glaux maritima L. Oecologia 29(4):349-357.
The Great Plains Flora Association. 1986. Flora of the Great Plains. University Press of Kansas, Lawrence. 1,402 pp.