Botrychium species

Grape Ferns and Moonworts

Leathery Grape Fern, Farm Lake, St. Louis County, Minnesota, Photo copyright 2002 by Earl J.S. Rook
Leathery Grape Fern
Farm Lake, St. Louis County, Minnesota
Photo © 2002 by Earl J.S. Rook

Flora, fauna, earth, and sky...
The natural history of the northwoods


Name:

  • Botyrichium, from the Greek botrus (botrys), "grape"
  • Grape Fern, from the prominent clusters of round spore cases which resemble miniature clusters of grapes.
  • Moonwort, from the "half moon" leaflets and the Anglo-Saxon wort, "plant"

Taxonomy:

  • Kingdom Plantae, the Plants
    • Division Polypodiophyta, the True Ferns
      • Class Filicopsida
        • Order Ophioglossales
          • Family Ophioglossaceae, the Adder's Tongue or Succulent Ferns
            • Genus Botrychium, the Grape Ferns
  • Taxonomic Serial Number: 17170
  • North Country Grape Ferns
  • North Country Moonworts
    • campestre, Iowa Moonwort (SSC-MN)
    • lunaria, Common Moonwort (TH-MN)
    • minganense, Mingan Moonwort (SSC-MN)
    • pallidum, Pale Moonwort (EN-MN)
    • pseudopinnatum, False Daisyleaf Moonwort
  • 50-60 species worldwide; 30 in North America.

Description:

  • A highly variable genus of small, rare (or, at least, much overlooked), un-fernlike ferns.
  • Sterile Frond (trophophore) a single leaf, ascending to perpendicular to stem, with or without leaf stalk
    • Blades linear, oblong, or deltate; simple to highly dissected; 1½"-10" × ½"-14"
    • Pinnae (leaflets) spreading to ascending, highly variable (fan-shaped to lanceolate to linear); edges smooth to toothed. Reduced to segments in many species.
  • Fertile Frond (sporophore) a stalk terminating in a cluster of tiny ball-like spore cases (sporangia) that resemble a bunch of grapes (hence the generic common name of "Grape Fern").
  • Stem single, upright, succulent, fragile, sometimes hollow. Several layers of leaf primordia at base of stem and just below the ground, from which will develop leaves of future seasons.
  • Roots thick, spongy, occasionally branching laterally, yellowish to black, 0.5mm-2mm in diameter, smooth or with corky ridges, not proliferous.

Identification:

  • Identifiable as Botrychium by the single succulent stem bearing a single leaf and a single fertile stalk, topped with clustered spore cases.
  • Field Marks
    • succulent, fragile, sometimes hollow stem
    • single leaf, lobed or compound
    • fertile stalk, usually branched, and topped with clusters of spore cases
    • diminutive size (usually)

    Botrychium ID for the North Country

    1. The Grape Ferns tend to be small, rare, and easily overlooked. There is one exceptions in our area. The Rattlesnake Fern, Botrychium virginianum is much larger (12"-18" tall) and easily the most commonly seen Grape Fern in the North Country.
      • Recognized as a Grape Fern by its large, single leaf and, in early summer, the single fertile stem arching above it.
      • Distinguished from other northern Grape Ferns by its much larger size and the lacy, thin textured, non-leathery leaf.
    2. If you have a small Grape Fern, look at the single leaf.
      • If the leaf is broadly triangular, you have Botrychium multifidum, Leathery Grapefern. The leaf will also be relatively large (for a Grape Fern), with dense overlapping leaflets and long, prominent leaf stalk. The Dissected Grape Fern, Botrychium dissectum, a more southerly species, has been collected once in St. Louis County, and is differentiated by its highly dissected leaflets.
      • If the leaf is twice cut into narrow and pointed segments (lance-shaped or lanceolate) you have Botrychium lanceolatum, Lance Leaf Grape Fern, a Threatened Species in Minnesota. The leaf will be small (only about 1" long) and high on stalk, resembling a daisy leaf in shape. The fertile frond will be branched into several equally long branches.
      • If the leaf is twice cut into broader lobes with more rounded tips, you have Botrychium maticariifolium, Matricary Grapefern. The leaf will be small (only about 1" long), oblong, and pale green; often clasping spore-bearing stalk. The fertile frond will be branched into several branches of unequal lengths. A close relative of the Matricary Grape Fern, Botrychium acuminatum, Tailed Grape Fern, is found in the Lake Superior region in North Ontario and the UP. It has been collected once in our area, in Cook County.
      • If the leaf is simply compound leaf (undivided lobes), you almost certainly have the highly variable Botrychium simplex, Small Grape Fern, a Species of Special Concern in Minnesota. Further solidify the identification by the combination of very small size (leaf only about 1½" long, plant less than 5½" tall), unbranched fertile frond, and clasping, simply compound leaf.
      • If the leaf is narrow and upright, made up of pairs of fan shaped leaflets, you have a Moonwort.
        • If the leaflets are broad and often overlapping, then you have Botrychium lunaria, Common Moonwort, a Threatened Species in Minnesota.
        • If the leaflets are narrow and widely spaced, then you have Botrychium minganense, Mingan Moonwort, a Species of Special Concern in Minnesota.
        • If the leaflets are often folded longitudinally and pale green to whitish in color, then you have Botrychium pallidum, Pale Moonwort, an Endangered Species in Minnesota.
        • Two other species of Moonwort have been collected but once in NE Minnesota, Iowa Moonwort, Botrychium campestre, and False Daisyleaf Moonwort, Botrychium pseudopinnatum.

Distribution:

  • The greatest diversity in Botrychium is at high latitudes and high elevations, mostly in disturbed meadows and woods.
  • Our North Country species are widely distributed across northern North America.
  • Many species are circumpolar, occurring in Europe and Asia as well.
  • Our 12 North Country species have all been recorded in Northeastern Minnesota, but only the Rattlesnake Fern (Botrychium virginianum) is at all common, the others ranging from rare to extremely rare.

Habitat:

Fire:

Associates:

History:

Uses:

Reproduction:

  • By means of microscopic spores.
    • Spore germinates, developing into a tiny underground structure (gametophyte) that produces the gametes (egg and sperm).
    • Mature sperm is released from one part of the gametophyte and swims via a thin film of water to the egg.
    • Fertilized zygote then develops roots, stem, and the above-ground structure recognizable as a fern (sporophyte).
    • Sporophyte produces the spores by the thousands in round sacs (sporangia) borne in clusters at the top of the fertile stalk.
  • Growth rate is slow; typically only a single leaf is produced each year. Primordia for several years are contained within the bud, but only one matures each season.
  • Several species undergo periods of dormancy, where the plant will not appear for one to several years and then re-emerge in the exact same location.

Propagation:

  • By spore (difficult)

Cultivation:

  • Our species hardy to USDA Zones 3 and 2 (average minimum annual temperature -40º to -50ºF)
  • Most species not suitable for cultivation.

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Last Updated on 26 February, 2004