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Order Ophioglossales
Order Ophioglossales
The Ophioglossoid ferns are a cryptic group of small fern-like plants called the Rattlesnake ferns, Grape ferns, Moonworts, and the Adder's-tongue ferns. All members are composed of a single upright vegetative leaf and a single fertile leaf. Some have a small compound frond, and others have an entire leaf. One taxon, Ophioglossum reticulatum, has the highest chromosome number of any known organism (2n=1260)! In a phylogenetic analysis, the Ophioglossales form a sister group with the whisk ferns (i.e. Psilotum & Tmesipteris).
Above: (left) Ophioglossum; (center-left) Botrypus; (center-right) Botrychium; (right) Helminthostachys
Ecology and habit
Ecology and habit
Temperate and tropical terrestrial and epiphytic plants
Sporophyte (=spore-bearing phase)
Sporophyte (=spore-bearing phase)
Vegetative features
Vegetative features
Stem
Corm-like rhizome
Siphonostelic vascular architecture
Periderm production has been reported in Botrychium, Botrypus, Helminthostachys, and Ophioglossum ( Peterson 1971, Takashi and Kato 1988).
Some reports indicate secondary xylem (wood) in this group, but close examination of Botrychium indicates there is no vascular cambium, nor is there secondary phloem (Rothwell & Karrfalt 2008)
Leaves
Compound or simple leaves; megaphylls
Single vegetative leaf
Single fertile leaf
Roots
Roots present
Reproductive features
Reproductive features
Sporangia
Sporangia, born in clusters on fertile leaf (sporophyll)
Sporangia are eusporangiate (larger sporangia with many spores)
Gametophyte (=gamete-bearing phase)
Gametophyte (=gamete-bearing phase)
Gametophytes are subterranean, lacking chlorophyll
Symbiosis with an endophytic fungus provides the requisite nourishment
Diversity
Diversity
Family Ophioglossaceae
Family Ophioglossaceae
Ophioglossum
Ophioderma
Helminthostachys
Mankyua
Family Botrychiaceae
Family Botrychiaceae
Botrypus (the rattlesnake fern)
Sceptridium (the grape-ferns)
Botrychium (Moonworts)
Geologic Age
Geologic Age
Carboniferous (?) - present (Pryer et al., 2004)
The Ophioglossales represent a stem group in the monilophytes, but lack a good fossil record.
Molecular estimates place their origin in the Carboniferous (Pryer et al., 2004)
The earliest report of ophioglossalean ferns in the fossil record is from spores preserved in Jurassic sediments of Russia
Well-preserved macrofossils of this group date to the Paleocene (Rothwell and Stockey, 1989)
Above: Fertile and vegetative leaves of Ophioglossum
Above: Compound leaf of Botrychium
Above: Fertile and vegetative leaves of Botrychium lunaria
Additional Resources
Additional Resources
An Awesome Ophioglossum (In Defense of Plants May 2016)
A Fern With Flower Genes - An Odd Case of Horizontal Gene Transfer (In Defense of Plants, December 2015)
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