- Scientific name: Sanicula trifoliata E.P.Bicknell
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
Description
Photograph by Peter M. Dziuk, MinnesotaWildflowers.info
Trefoil sanicle is a biennial plant, or a “facultative perennial” (Hawkins et al. 2007). A facultative perennial grows larger each year until it finally sends up a flowering shoot which can take two or more years. It produces a single stem that grows 30-75 cm (1-2.5 ft) tall. The alternate leaves at the base of the stem have long petioles (leaf stems) and are palmately divided into 3 leaflets (trifoliate). As the leaves go up the stem, they become gradually smaller and the petioles are shorter or non-existent (i.e., the leaves are sessile). The leaflets are coarsely or double toothed or serrate, with some lateral leaflets also deeply incised. There are separate male and female flowers on all Sanicula (the plants are monoecious). There are typically 3 female flowers that are sessile at the end of a flowering stem and a few staminate flowers on long (3-6 mm [0.12-0.24 in]) pedicels, extending beyond the female flowers. The female flowers are at the end of the bristle covered, swollen fruit (schizocarp). Both types of flowers have five white petals and five lanceolate sepals (calyx); the female flower sepals are slightly longer than the hooked bristles on schizocarp, and the styles do not protrude beyond the calyx. The sepals on the schizocarp form a conspicuous beak 2-2.5 mm (0.08-0.1 in) that other Massachusetts species of sanicle do not have. The schizocarp is 6-8 mm (0.24-0.31 in) long including the beak and does not split open (Gleason and Cronquist, 1991).
| Sanicle Species | Calyx | Bristles | Styles | Umbellets |
|---|---|---|---|---|
| Clustered sanicle, S. odorata | Triangular, blunt, shorter than bristles | Not conspicuously expanded at base | Recurved, much protruding beyond calyx | Staminate and polygamous |
| Trefoil sanicle, S. trifoliata | Lanceolate, sharply tipped exceeding bristles | Expanded at base | Not protruding beyond calyx | Only polygamous |
| Canadian sanicle, S. canadensis | Lanceolate, sharply tipped, concealed by bristles | Expanded at base | Not protruding beyond calyx | Only polygamous |
| Black snakeroot, S. marilandica | Long, pointed; inconspicuous among bristles | Expanded at base | Recurved, much protruding beyond calyx | Staminate and polygamous |
Lower stem leaf with deeply incised lateral leaflets. Photograph by Peter M. Dziuk, MinnesotaWildflowers.info.
Close up of flowering head. Photograph by Karro Frost.
Life cycle and behavior
Trefoil sanicle is a biennial plant, or a “facultative perennial” (Hawkins et al. 2007). A facultative perennial grows larger each year until it finally sends up a flowering shoot which can two or more years. Trefoil sanicle may be found in flower from late May to early July. Once it flowers and sets seed, the plant will die. Seeds ripen from July through September. However, the mature mericarps will remain on the dead parent plant until they have attached to the fur of an animal or feather of a bird. It may be one or more years before they are removed from the dead stem of the parent plant. Pollination is thought to be by small flying insects as it is in other sanicles (Johnson 2023). Hawkins et al. (2007) report their findings from seed germination studies indicating that some seeds may not germinate until the 6th year, which indicates that trefoil sanicle might create a persistent seed bank in the soil, and sprout when the conditions are appropriate. Several other species of sanicle have been found to associate with arbuscular mycorrhizae, it is likely that trefoil sanicle has a similar association (Johnson 2023).
Population status
Trefoil sanicle was recently listed as a species of greatest conservation need and is maintained on Massachusetts plant watch list. There are currently 11 known occurrences in the state verified since 1999 found in Berkshire, Franklin and Hampden Counties. The Consortium of Northeastern Herbaria has recent specimens of this species from Hampshire County (CNH 2025).
Distribution and abundance
Trefoil sanicle is known in Canadian provinces New Brunswick, Quebec and Ontario, south to Alabama and Georgia. It is of conservation concern, including critically imperiled in Delaware, Georgia, New Jersey and South Carolina. In New England, it is considered imperiled in Massachusetts and New Hampshire and vulnerable in Vermont. There is no state rank for the species in Connecticut, Maine and Rhode Island.
Distribution in Massachusetts
1999-2024
Based on records in the Natural Heritage Database
Habitat
The habitat of trefoil sanicle in Massachusetts is typically mesic deciduous hardwood forests on north or eastern facing slopes and may occur in shaded areas. It is frequently found in calcium rich soils, on steep slopes. The species may also be found in nutrient rich forests in riparian habitats. Associated species may include sugar maple (Acer saccharum), beech (Fagus grandidentata), basswood (Tilia americana), white ash (Fraxinus americana), and red oak (Quercus rubra). Herbaceous associates may include blue cohosh (Caulophyllum spp.), Canada violet (Viola canadensis), northern maidenhair fern (Adiantum pedatum), silvery glade fern (Deparia acrostichoides), Christmas fern (Polystichum acrostichoides), wild ginger (Asarum canadense), bloodroot (Sanguinaria canadensis), doll’s eyes (Actaea pachypoda), herb-Robert (Geranium robertianum), Jack-in-the-pulpit (Arisaema trifolium), wood nettle (Laportia canadensis), and foam flower (Tiarella stolonifera). This species is sometimes considered an indicator of mature forests.
Healthy habitats are vital for supporting native wildlife and plants. Explore habitats and learn about conservation and restoration in Massachusetts.
Threats
The primary threats to trefoil sanicle are habitat loss through construction and activities that open large canopy gaps or disturb the soil, and invasive plant species. Some species, such as garlic mustard (Alliaria petiolata) alters the arbuscular mycorrhizal community. Non-native earthworms may also be a threat through their soil disturbance. Climate change is likely to impact the mesic deciduous forests where this species grows with changes in temperatures, and precipitation patterns (Staudinger et al. 2024). Motorized vehicles in the mesic forest habitats can lead to soil compaction and introduction of invasive species.
Conservation
Survey and monitoring
Regular monitoring and reporting of trefoil sanicle to MassWildlife’s Natural Heritage and Endangered Species Program will help to understand how threatened this species and its habitats are. The size of the populations has not often been reported, though this is important for species assessment. The best time to survey the species is in July and August when the fruits are present and lead the observer to confidently identify the species of sanicle.
Management
Management activities should include land protection of the habitats where trefoil sanicle occurs. Invasive species control is also important for maintaining trefoil sanicle populations and should occur soon after invasive species are first observed in the habitat so they do not become well established. All active management of rare plant populations (including invasive species removal) is subject to review under the Massachusetts Endangered Species Act and should be planned in close consultation with the MassWildlife’s Natural Heritage & Endangered Species Program.
Research needs
Trefoil sanicle is an under-surveyed and under reported species. More standard information is needed such as lists of associated species, comments on habitat quality and threats, and assessments of soil conditions and phenology. Research is needed to determine whether this plant can be grown in a nursery or garden setting for purposes of reintroductions. If habitat degradation accelerates losses of current populations, this strategy could prove useful to long-term conservation of this species.
References
Bplant.org “Compare Plants: Canadian Blacksnakeroot vs Largefruit Blacksnakeroot, https://bplant.org/compare/1273-1276 Accessed 4/9/2025.
Gleason, Henry A., and Arthur Cronquist. Manual of Vascular Plants of Northeastern United States and Adjacent Canada, Second Edition. Bronx, NY: The New York Botanical Garden, 1991.
Haines, A. 2011. Flora Novae Angliae – a Manual for the Identification of Native and Naturalized Higher Vascular Plants of New England. New England Wildflower Society, Yale Univ. Press, New Haven, CT.
Hawkins, T. S., J. M. Baskin, and C. C. Baskin. 2007. Seed morphology, germination phenology, and capacity to form a seed bank in six herbaceous layer Apiaceae species of the eastern deciduous forest. Castanea 72(1):8-14.
Herbarium specimen data provided by: [Harvard University Herbaria, ] (Accessed through the Consortium of Northeastern Herbaria web site, www.neherbaria.org, Accessed 4/8/2025)
Johnson, Elizabeth A. 2023. Sanicula trifoliata Rare Plant Profile. New Jersey Department of Environmental Protection, State Parks, Forests & Historic Sites, State Forest Fire Service & Forestry, Office of Natural Lands Management, New Jersey Natural Heritage Program, Trenton, NJ. 14 pp.
MNDNR (Minnesota Department of Natural Resources). 2025. Sanicula trifoliata. https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=PDAPI1Z0L0#:~:text=Sanicula%20trifoliata%20is%20a%20biennial,and%20palmately%203%2Dparted%20blades Accessed 3/9/2025.
NatureServe. 2025. NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org/. Accessed: 4/9/2025.
POWO (2025). Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; https://powo.science.kew.org/ Accessed: 4/8/2025.
Seymour, Frank C. 1969. The Flora of New England, First edition. Charles E. Tuttle Company, Inc. Tokyo, Japan.
Staudinger, M.D., A.V. Karmalkar, K. Terwilliger, K. Burgio, A. Lubeck, H. Higgins, T. Rice, T.L. Morelli, A. D'Amato. 2024. A regional synthesis of climate data to inform the 2025 State Wildlife Action Plans in the Northeast U.S. DOI Northeast Climate Adaptation Science Center Cooperator Report. 406 p. https://doi.org/10.21429/t352-9q86
Contact
| Date published: | May 9, 2025 |
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