Clearwater National Forest
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CRENULATE MOONWORT Botrychium crenulatum Wagner STATUS USFS Region 1: Sensitive USFWS: SC (species of concern) ICDC: G3/S1 INPS: GP3 (global priority 3) TAXONOMY Family: Ophioglossaceae (adder's tongue) Common Name: crenulate moonwort Synonyms: B. lunaria (L.) Swartz var. onondagense (Underw.) House Description A thin and delicate, perennial plant with a pale yellow-green color that grows to about 10 cm tall. Plants arise from a single stem that divides into a single fertile and sterile "leaf", both attached near the middle of the plant from a 3-5 cm long common stem. The sterile leaf is attached to the main stem by a short (5 mm) stalk, once divided into 2-5 pairs of lateral segments (pinnae) that are strongly flabellate with entire to shallowly-scalloped outer margin. The fertile portion ranges from 2.5-9.5 cm long (Wagner and Wagner 1981, Wagner and Devine 1989, Lellinger 1985). Plants emerge in late spring and release spores in summer and early fall. Vesicular-arbuscular mycorrhizae (VAM) are required by both the sporophyte and gametophyte stages of the life cycle of Botrychium . Soil disturbance or weed colonization can reduce or remove VAM from the soil. For reproductive biology, see B. minganense Distinguishing Features and Similar Species There are few well developed features to determine the species of this genus. Consequently there are many species which are very similar and difficult to distinguish from B. crenulatum. The 2-3 (sometimes up to 5) pair of non-overlapping, fan-shaped pinnae are the key to recognizing this species. The pinnae are very thin and the veins readily show when the plant is held up to the light. This species may be especially difficult to separate from B. minganense based on visible characters and sometimes only genetic analysis can be relied upon. Not all of the Idaho occurrences have been verified by experts. For many years crenulate moonwort and other similar species was confused with B. lunaria and treated as a variety of that species. B. crenulatum has broader, fan-shaped pinnae that have crenate margins. The 2-3(5) pairs of pinnae do not overlap. B. lunaria has pinnae that are broad and fan shaped and strongly overlap. B. minganense has greater that 4 sets of pinnae that are cup or wedge shaped and also do not over lap. The pinnae of B. ascendens are very similar but the cup shaped pinnae has margins that are deeply incised to divided and also generally are found in greater than 3 pairs. B. montanum has 1-2 pairs of pinnae with bases as broad as the long and often irregular proximal margins. These segments are often long rectangular to rhombus shaped or sometimes strongly amorphous (Wagner and Wagner 1981, Wagner 1992). B. sublunaria is also similar but its pinnae are narrowly fan to cup shaped and the plant otherwise most similar to B. minganense (Wagner 1999). DISTRIBUTION Range Crenulate moonwort is very rare and local, but exhibits a rather extensive range. It is known to occur from as far north as Oregon, Montana and Alberta and as far south as Utah (Wagner and Devine 1989). Two historical collections from northern Idaho have been identified as B. crenulatum. One site is from Boundary county while the other is from Clearwater County. The latter was collected near Washington Creek from the vicinity of the boundary between Potlatch Corporation land and the Clearwater National Forest. The exact land ownership is unknown and no attempt has been made to relocate the site. Habitat Crenulate moonwort grows principally at drier microsites of damp meadows, boggy areas and marshy places at low elevation. Plants are generally rooted around trees or shrubs or in depressions at the edge of marshes that dry out during the summer. It may occur either in sun or shade, but evidently prefers partial shade. It is also found on old road surfaces in parts of its range. Such roads have a grass, forb and/ or moss cover and lack substantial shrub or tree cover. However, like most other moonworts, the known Idaho locations are found in climax western redcedar forests. REMARKS Crenulate moonwort is very rare in Idaho. Like most moonworts in the state, it generally has a strong affinity to old growth western redcedar groves. Timber harvest or any activity impacting the moisture of a site is expected to have an adverse effect on this species. However, such habitats are generally protected today, eliminating threats to this species and its suspected habitat. In Washington State, this species has been found in meadow habitats. Studies of the impacts of grazing on moonworts in these meadows show the plant can withstand, perhaps increase in areas of light grazing. Heavy grazing however, extirpated the plants (Wooten 1993). Low levels of disturbance, such as grazing has been cited as a way to maintain populations on old abandoned roads (Wagner 1999). Searches of meadow habitats and old road beds in Idaho have yet to reveal any populations. REFERENCES Lellinger, D.B. 1985. A field manual of the ferns and fern-allies of the United States and Canada. Smithsonian Institution Press, Washington D.C. 389 pp. Wagner, W.H. 1999. University of Michigan. Personal communication. Wagner, D.H. 1992. A Key to Botrychium. University of Oregon, Eugene OR. 19 pp. plus appendices. Wagner, W.H. Jr. and T.B. Devine. 1989. Moonworts (Botrychium: Ophioglossaceae) in the Jonesville area, Butte and Tehama Counties, California. Madrono 36(2):131-136. Wagner, W.H. Jr. and F.S. Wagner. 1981. New species of moonwort, Botrychium subgenus Botrychium (Ophioglossaceae), from North America. American Fern Journal 71:20-29. Wooten, G. 1993. Botrychium Trampling study. Unpublished report. USFS Region 6, Okanogan National Forest.
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