Subterranean Sporophytic Gemmae in Moonwort Ferns, Botrychium Subgenus Botrychium

Abstract

Underground gemmae in Botrychium subgenus Botrychium are described as the first report of such structures in ferns. Gemmae are spherical units 0.5–1 mm in diameter produced on the stem, where they originate in meristematic regions of the outer cortex. At maturity they contain an embedded apical cell and may contain a mycorrhizal fungus. Upon abscission from the stem they remain subterranean and may undergo growth and development into completely differentiated sporophytes in a pattern similar to that of development of sexually produced embryos. In addition to the diploid B. campestre, gemmae occur in the tetraploids B. minganense, B. echo, and a new species as yet undescribed. These may be allotetraploids of which B. campestre is one parent. The ecological significance of reproduction by gemmae may lie in the advantages of asexual reproduction in the dry prairie habitat of B. campestre.

Slender Moonwort, <em>Botrychium lineare</em> (Ophioglossaceae), Rediscovered in Quebec

“…tenebrosum and B. matricariifolium superficially resemble B. lineare, but B. campestre is a closer relative (Wagner and Wagner 1994;Farrar 2006*). Botrychium simplex var.…”

“…Moonwort classification and identification are very complex (Farrar 2006*;unpublished data). Identifications based on undeveloped specimens are challenging even for specialists.…”

“…They are both diploid species, rather short, with very short sporophore stalks, and with trophophore segments narrow, linear or spatulate, relatively undivided (or, if divided, palmately cleft into two to four segments) and frequently well spaced and separated (Farrar 2006*).…”

“…The main differences are related to their morphology, ecology and phenology (Wagner and Wagner 1994;Farrar 2006*). At the morphological level, the trophophore rachis of Botrychium campestre is fleshy and broad, up to one-third as wide as the whole trophophore, dull and whitish green, their segments linear to spatulate, commonly overlapping or fused, clearly enlarged at the apex, up to 3-5 lobed, the longest segments toward the upper portion of the trophophore; the entire sporophore length is 1.0-1.5 times that of the trophophore.…”

“…This species appears very early. In Iowa, the trophophores are out in April and have disappeared in mid-June (Farrar 2006*). Spores start to mature in May.…”