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Marsh Felwort - Lomatogonium rotatum
State Rank Reason (see State Rank above)
DRAFT: Requesting feedback on the 2026 revised rank, factors, and State Rank Reason outlined below and in the Conservation Status Rank Report.
Lomatogonium rotatum is very rare in the state, being known from only 3 occurrences in Beaverhead County. 2 occurrences are known only from their original collections in 1994 and have not been resurveyed. One of these had over 500 plants, while the other one apparently had less than 100 plants. The third occurrence was documented in 2013-2014 and appeared to be a small population. Trends are unknown, though the habitat would appear to be intact. Threats were not documented/recorded during the surveys. All sites apparently receive some livestock grazing, and it is unclear what, if any, impact this may have on the species.
Surveys are needed to relocate the 2 populations on federal lands that were documented in 1994. If located, current data on population size and extent, habitat condition and extent, and potential threats are needed. Monitoring of the populations is needed to determine trends and what, if any, impact grazing may have on the species.
General Description
Felwort is a glabrous annual with usually unbranched stems that are 5-15 cm high. The opposite leaves are narrowly oblong to lance-shaped and 1-3 cm long. White or bluish flowers are borne on slender, 1-3 cm long stalks which arise from the axils of the upper leaves. The 5 spreading, lance-shaped petals are 6-15 mm long and are united at the base and subtended by slightly longer, narrow, green sepals. Each petal has 2 small appendages at the base, and there are 5 stamens. The fruit is a many-seeded, egg-shaped capsule that is as long as the petals.
Phenology
Flowering in August.
Diagnostic Characteristics
Swertia perennis has similar flowers but is a perennial. Annual gentians have tubular rather than star-shaped corollas. This plant is often overlooked because it blooms in August.
Species Range
Montana Range
Range Descriptions
Native
Range Comments
Greenland to Alaska, south to Colorado.
Observations in Montana Natural Heritage Program Database
Number of Observations: 4
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Relative Density
Recency
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Alkaline meadows and fens in the montane zone.
National Vegetation Classification System Groups Associated with this Species
Wetland and Riparian
Alpine Riparian and Wetland
Peatland
Wet Meadow and Marsh
Stewardship Responsibility
References
- Additional ReferencesLegend:
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Famous, N. C. and C. S. Campbell. 1984. Lomatogonium rotatum (Gentianaceae) and Primula laurentiana (Primulaceae) in Maine: New locations and general distribution. In prep.- Famous, N. C., and C. S. Campbell. 1985. Lomatogonium rotatum. In: The Nature Conservancy Element Stewardship Abstract [Data base]. Boston, MA: The Nature Conservancy, Eastern Regional Office.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
- Lesica, P., P. Husby, and S. V. Cooper. 1998. Noteworthy collections: Montana. Madrono 45:328-330.
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