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Botrychium ascendens Wagner

Triangular-lobed Moonwort; Upswept Moonwort

Ophioglossaceae (Grape fern family)

General Description: Plants are comprised of a single above-ground bright yellow-green frond that is usually about 10 cm tall. It is divided into two segments that share a common stalk. The mostly sterile segment is once-pinnatifid with as many as ten pairs of strongly ascending, narrowly triangular pinnae that have deeply lacerate margins. There are often a few sporangia on the margins of the lower pinnae of the sterile leaf segment. When mature, the fertile segment is longer than the sterile segment, is branched, and bears grape-like sporangia.

Illustration.

Field Identification Tips: Although B. ascendens is reported as the only moonwort to commonly have extra sporangia on the proximal pinnae, this condition has been observed on several other moonwort species as well.

Phenology: Leaves appearing in late spring to mid-summer. Spores produced July-August.

Similar Species: Both B. minganense and B. crenulatum have more spreading pinnae with entire to crenulate margins, compared to the strongly ascending pinnae with sharply serrate or incised margins characteristic of B. ascendens. In addition, B. minganense possesses a deep, dull green color versus the bright yellow-green of B. ascendens. Botrychium lunaria has overlapping, entire-margined leaflets and spreading vegetative segments.

Habitat: In north Idaho it is most commonly found in moist, western redcedar forests. It has been found in grassy fields, moist meadows, and shrub or conifer dominated wetlands up to about 2,500 m elevation elsewhere in the Pacific Northwest.

Global Distribution: Widely scattered from the Yukon to Ontario, southward to northern California, Nevada, Oregon, Washington, Idaho, Montana, and Wyoming.

Idaho Distribution: Known from the Kootenai River and Moyie River drainages in Boundary County and near Lake Pend Oreille in Bonner County.

References:

Brooks, P. J., K. Urban, E. Yates, and C. G. Johnson, Jr. 1991. Sensitive plants of the Malheur, Ochoco, Umatilla, and the Wallowa-Whitman National Forests. U.S. Department of Agriculture, Forest Service, Pacific Northwest Region.

Fertig, W. 1994. Wyoming rare plant field guide. Prepared for the Bureau of Land Management, U.S. Fish and Wildlife Service, U.S. Forest Service, National Park Service, and Wyoming Game and Fish Department by the Wyoming Natural Diversity Database.

Flora North America Editorial Committee. 1993. Flora of North America, Vol. 2. Pteridophytes and Gymnosperms. Oxford University Press, Inc., New York. 475 pp.

Mantas, M., and R. S. Wirt. 1995. Moonworts of western Montana (Botrychium subgenus Botrychium). Unpublished report prepared for the Flathead National Forest, Kalispell, MT.

Montana Natural Heritage Program. Montana rare plant field guide. Available at: http://nhp.nris.state.mt.us.

Vanderhost, J. 1997. Conservation assessment of sensitive moonworts (Ophioglossaceae; Botrychium subgenus Botrychium) on the Kootenai National Forest. Unpublished report prepared for the Kootenai National Forest, Libby, MT. 83 pp. plus appendices.