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Rugulose Grape-fern (Sceptridium rugulosum)

Photo © N.L. Taylor
Life history
Species overview
Rugulose Grape-fern (Sceptridium rugulosum), a Wisconsin Special Concern plant, is found on sandy shorelines of fluctuating lakes and ponds. The optimal identification period for this species is early June through late August.
Synonyms: Botrychium multifidum f. dentatum, Botrychium ternatum
Identification
- Distinguishing characteristics: Stalk of the sterile laminae less than 2 mm in diamter; basal pinnae of frond distant from adjacent pinnae, some blades, therefore, ternate; pinnae divided to tip of blade (unlike B. oneidense and B. dissectum, which tend to be merely lobed toward the tip), and apex of pinnae of the laminae acute (unlike the rounded apex of B. multifidum); segments of blade somewhat channeled or concave in living specimens (unlike the flattened, planar blades of B. multifidum).
- Flower characteristics:
- Fruit characteristics: Basal, fertile portion of frond is an erect spike that is 6 to 19 cm long and slightly to many times longer than the sterile portion, pinnately branched at its apex, each branch and brachlet bears two rows of sporangia not or only slightly embedded in the branch.
- Leaf characteristics: Frond deltate to broadly lanceolate, 2.5 to 9 cm long, 2.5 to 9 cm wide, 2 to 3 times pinnate with ovate pinnae having an acute apex and margins entire to irregularly toothed or finely lobed; pinnae divided to the tip of the frond.
Phenology
- Blooming phenology:
- Fruiting phenology: late September
- Optimum time to identify: The optimal identification period for this species is early June through late August
Other
- Growth form: Fern
- Vegetative reproduction: Rhizomatous
- Life cycle: Perennial
- Comments: Associated Species: Botrychium dissectum, B. multifidum, Calamagrostis canadensis, Solidago altissima, Pinus banksiana.
State status
Status and Natural Heritage Inventory documented occurrences in
Wisconsin
The table below provides information about the protected status -
state and federal - and the rank (S and G Ranks) for Rugulose Grape-fern
(Sceptridium rugulosum). See the Working
List Key for more information about abbreviations. Counties shaded
blue have documented occurrences for this species in the Wisconsin
Natural Heritage Inventory database.
The map is provided as a general reference of where this species has
been found to date and is not meant as a range map.
Summary Information |
State Status | SC |
Federal Status in Wisconsin | none |
State Rank | S2 |
Global Rank | G3 |
Tracked by NHI | Y |
Habitats and landscapes
The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.
General habitat information
- Habitat description: Found on sandy shorelines of fluctuating lakes and ponds.
- Soils: Moist soils.
Natural communities
This table lists the natural communities that are associated with Rugulose Grape-fern. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).
Ecological landscapes
This table lists the ecological landscape association scores for Rugulose Grape-fern. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.
Species guidance
The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.
Avoidance measures
These are specific actions designed to avoid "take" (mortality) of this species.
- Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.
- Avoid broadcast spraying of herbicides; use care with spot spraying.
Management guidance
Management guidelines are additional considerations that may help maintain or enhance habitat for this species
- Minimize disturbance to hydrology, including soil disturbance from rutting.
- Avoid disturbance to shorelines and the forest-beach interface.
Other resources
Links to additional Rugulose Grape-fern information
Other links related to vascular plants (all exit the DNR website)
Photos
Click to view a larger version. Please considering donating a photo to the Natural Heritage Conservation Program for educational uses. Photo use

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Botrychium rugulosum is a globally rare fern that is known from two locations in the Northwest Sands ecological landscape.
Photo © N.L. Taylor.

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Photo © Stephen L. Solheim.
Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].
Last revised: Wednesday, May 05, 2021