Rare Species Guide

  Basis for Listing

Botrychium neolunaria (New World moonwort), as it is now understood, occurs across boreal North America, including Minnesota. The closely related B. lunaria (common moonwort) occurs in far northern North America as well as in northern Europe and Asia. It is not known to occur in Minnesota. It was only in 2016 that they were discovered to be two separate species (Stensvold and Farrar 2016). Before that, they were considered to be a single circumboreal species that was common in many parts of the world. That is why the 1996 list of threatened Minnesota species lists it as B. lunaria. The change in our understanding of the species does not change its status in Minnesota, except to make occurrences in Minnesota somewhat more important to conservation across its range. Within the state, it is very rare and dependent on poorly know ecological factors.

  Description

Botrychium neolunaria may be 2.5-17.8 cm (1.0-7.0 in.) tall with a single leaf bearing per season. The leaf is divided into two segments; a fertile segment that produces the spores, and a sterile segment that performs photosynthesis. The sterile segment has up to 9 pairs of fan-shaped pinnae that often overlap, except when growing in deep shade. The fertile segment bears several round spore cases that turn yellow when ripe. After shedding spores in July, the sterile segment begins to wither, but the fertile segment remains green until fall. Botrychium neolunaria may occur with other species of Botrychium, such as B. minganense (Mingan moonwort), with which it is often confused. Botrychium minganense can be distinguished by the elongate sterile segment of the leaf that has narrower nonoverlapping pinnae. Large specimens of B. minganense may have pinnae with 1 or more shallow incisions.

  Habitat

In Minnesota, B. neolunaria appears to prefer semi-open habitats such as gravelly banks, rocky ledges, and talus in the northeastern counties (Northern Superior Uplands Section). In the northwestern counties (mostly Agassiz Lowlands Subsection), it is most often found in forest clearings of human origin, which may resemble grassy meadows. Habitats also include utility corridors kept clear of encroaching trees and shrubs and forest clearcuts where regeneration has been delayed, but where the soil has been left undisturbed. Along the shore of Lake Superior (North Shore Highlands Subsection), B. neolunaria has been found in fire-dependent forests among mosses and lichens where there is a history of timber harvest and fire, though it has not been found in habitats where severe disturbances have been recent.

  Biology / Life History

Typically, one leaf emerges per year in spring, dying in the latter half of summer or early fall after releasing spores. However, an individual plant may not appear aboveground for one or more years, possibly due to stress such as drought. It is not unusual for B. neolunaria populations to fluctuate without determinable cause (United States Forest Service 1999). Like all ferns, B. neolunaria has an underground gametophyte stage (the sexual stage) and an aboveground sporophyte stage (the non-sexual stage). It is the sporophyte stage that produces and disperses spores which result in the gametophyte stage. Each stage might last a few to several years, resulting in a total potential lifespan of 10—15 years. Populations can last much longer than the lifespan of an individual, but it is not known how long a typical population (or discrete group of plants) exists at any one place. Spores are typically dispersed short distances, usually just a few meters. It is thought that spores will not remain viable in the soil for more than a few years.

  Conservation / Management

Botrychium neolunaria is small, difficult to find, and it may be easily overlooked. In addition, it is often challenging to determine what factor or combination of factors is impacting B. neolunaria populations. Potential threats to plants include drought, fire, timber harvesting, herbicides, herbivory, non-native earthworms, and vegetation succession. Many of these activities have been shown to be detrimental to the aboveground portion of the plant, but effects on the viability of a population, including gametophytes and spores in the soil, are unknown (United States Forest Service 1999).

  Best Time to Search

The best time to search for Botrychium neolunaria is when it is at its peak of development, from June through mid-August.

  Authors/Revisions

Welby R. Smith (MNDNR), 2021

(Note: all content ©MNDNR)

  References and Additional Information

Olejnik N., and Z. Celka. 2015. The growth pattern of Ophioglossoid ferns: a case study of Botrychium lunaria (L.) Sw. American Fern Journal 105(3):199-210.

Smith, W. R. 2023. Ferns and lycophytes of Minnesota: the complete guide to species identification. University of Minnesota Press, Minneapolis. 368 pp.

Stensvold, M. C. and D. R. Farrar. 2016. Genetic diversity in the worldwide Botrychium lunaria (Ophioglossaceae) complex, with new species and new combinations. Brittonia 69(2):148-175.

U.S. Forest Service. 1999. Population viability assessment in forest plan revision. Statement of purpose and reason. Draft species data records: Botrychium lunaria. U.S. Forest Service, Region 9, Superior National Forest, Duluth, Minnesota.

U.S. Forest Service. 2000. Population viability assessment in forest plan revision. Questions for plant population viability assessment panel: Botrychium lunaria. U.S. Forest Service, Region 9, Superior National Forest, Duluth, Minnesota.

Wagner, W. H., Jr., and F. S. Wagner. 1993. Botrychium. Pages 86-101 in Flora of North America Editorial Committee, editors. Flora of North America north of Mexico. Volume 2. Oxford University Press, New York, New York.