The species is named for Oneida County, New York. The specimen used to describe this species was collected on the Mohawk Flats near Utica. During dry years this plant may not produce leaves at all but remain as an underground stem until wet weather returns.
There are eight existing populations, most of them of small size, but there are over 30 occurrences that have not been field checked. The difficulty of finding this small plant makes it more difficult to determine its true status.
Not enough data has been gathered to evaluate the short-term trend of this fern. Of the six populations that have been discovered since 1980 two have been revisited and the plants seem to be doing well.
There were about 30 populations discovered before 1980 and only one of these has been rediscovered. More effort needs to be given to redisovering these other sites, however, this is a plant that likely moves around within large landscapes. There is speculation that this plant has declined over the last 100 years, but more evidence is needed. Certainly a lot of potential habitat has been lost since European colonization.
The existing populations grow in areas that are mostly protected and are not subject to any immediate threats. Historical populations may be threatened by habitat development and wetland loss.
The forested areas where this species occurs need to remain undisturbed. A sufficient buffer should be established to prevent changes in ecological processes and the introduction of invasive species.
More specimens and photographs need to be collected to catalog the range of variation of this species in New York.
This fern is found on highly organic moist soils and sandy soils of mixed deciduous hardwood forests including the lower slopes of maple forests, secondary forests, wet woods along stream corridors, creek gorges, and other rich, moist forests (New York Natural Heritage Program 2006). In moist, shady, acidic woods and swamps (Flora of North America 1993). Rich moist woods and swamps (Gleason 1991). Low, wet, acid secondary woods and swamps (Wagner 1961).
Blunt-lobed grape fern is scattered across New York State south of the Adirondacks.
The range of Botrychium oneidense is from New Brunswick to Ontario, Canada, and Minnesota, south to North Carolina and Tennessee in the mountains. It seems to be most common in the center of its range from Pennsylvania to Michigan.
Blunt-lobe Grape Fern is a perennial, evergreen fern. Its roots are pale gray or ivory colored to tan, smooth, and average 2.5 mm diameter about 1 cm from the stem. This diameter decreases to 2.0 mm when dried. The common leaf stem of the fertile and sterile segments is up to 2 1/2 inches long while the leaf stem of the more erect fertile segment can be up to 9 inches long. This spore-bearing portion of the leaf can be up to 5 1/2 inches long. The leaf stem of the sterile leaf can be up to 10 inches long. The sterile leaf blade appears in the middle of May, is flat, leathery, dull bluish green, and grows up to 7 inches long and 6 inches wide. It is divided into two or three broadly triangular leaflets (pinnae). The terminal pinna blade is egg shaped in outline and larger than the lateral pinnae. The pinnae are again divided into pinnules which are divided into segments. The pinnules of the terminal pinna are more or less undivided at the tips. The ultimate segments of the pinnules are comparatively large and rounded, finely to bluntly toothed, to nearly smooth. The surface of the leaf is somewhat dull and smooth. When the leaves unfold in the spring they are lime green and remain in dull green throughout the winter where they are exposed.
Blunt-lobe Grape Fern is a perennial, evergreen fern. Roots pale gray or ivory colored to tan, smooth, average 2.5 mm diameter about 1 cm from the stem, 2.0 mm when dried. The common petiole of fertile and sterile segments up to 9 cm long. Petiole of erect fertile segment to 22 cm long, sporophyll to 14 cm long. Petiole of the sterile leaf to 14 cm long. Sterile leaf blade to 14 cm long and 23 cm wide, appearing in mid-May, divided into two or three broadly triangular pinnae. Terminal pinna ovate and larger than the lateral pinnae, pinnules more or less undivided at the tips. Ultimate pinnule segments obliquely ovate, apex rounded to acute, finely to bluntly toothed, to nearly smooth. Leaf surface somewhat dull and smooth. New spring leaves lime green remaining dull green throughout the winter where they are exposed.
Only the fully expanded leaf is needed for identification.
In Botrychium multifidum and Botrychium rugulosum the terminal pinna is about the same size as the lateral pinnae. The pinnules are regularly divided into segments of about the same size and shape right up to the tips of the pinnae. In Botrychium dissectum the roots are dark gray-brown and 3 mm diameter about 1 cm from the stem. The terminal pinna is narrowly lance-shaped and the ultimate segments of the pinnules are somewhat pointed. When the leaves unfold in the spring they are reddish and often turn bronze-colored in the winter. Botrychium oneidense is usually only found in low shaded forests and swamps where the other three closely related species can be found in open habitats.
The best time to identify this fern is from June through early fall. Even though the leaf is evergreen it is more difficult to see after leaf fall. It can be separated from Botrychium dissectum by the color of the new leaf in mid-May and the color of the old leaf in the fall, so ideally surveys would take places at these two different periods.
The time of year you would expect to find Blunt-lobe Grape Fern vegetative and fruiting in New York.
Blunt-lobe Grape Fern
Botrychium oneidense (Gilbert) House
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Information for this guide was last updated on: April 18, 2006
Please cite this page as:
New York Natural Heritage Program. 2019. Online Conservation Guide for Botrychium oneidense. Available from: https://guides.nynhp.org/blunt-lobe-grape-fern/. Accessed September 23, 2019.