Ophioglossum Explained

Ophioglossum, the adder's-tongue ferns, is a genus of about 50 species of ferns in the family Ophioglossaceae. The name Ophioglossum comes from the Greek meaning "snake-tongue".^[1] Their cosmopolitan distribution is mainly in tropical and subtropical habitats.^[1]

The genus has the largest number of chromosomes in the known plant kingdom, but contrary to popular belief does not have the largest number of chromosomes out of all known organisms, falling short to the protist Sterkiella histriomuscorum.

Description

Adders-tongues are so-called because the spore-bearing stalk is thought to resemble a snake's tongue. Each plant typically sends up a small, undivided leaf blade with netted venation, and the spore stalk forks from the leaf stalk, terminating in sporangia which are partially concealed within a structure with slit sides.^[1]

When the leaf blade is present, there is not always a spore stalk present, and the plants do not always send up a leaf, sometimes going for a year to a period of years living only under the soil, nourished by association with soil fungi.

The plant grows from a central, budding, fleshy structure with fleshy, radiating roots.

Ophioglossum malviae is known as the world's smallest terrestrial fern.^[2]

Taxonomy

Ophioglossum has a high chromosome count in comparison to other species, with 120 or up to 720 chromosomes possible in intervals of 120 due to polyploidy (multiple possible copies of chromosomes). It has almost 1260 number of chromosomes in the meiocyte (spore mother cell) which undergo meiosis, the reduction division to form the spore with only one set of chromosomes getting incorporated into each spore.^[3] The species Ophioglossum reticulatum has the highest number of chromosomes found in any multicellular organism.^[4]

Phylogeny

Phylogeny of Ophioglossum^{[5] [6]}

Unassigned species:^[7]

• (Goswamia)
  • Ophioglossum gujaratensis
  • Ophioglossum hitkishorei
  • Ophioglossum indicum
  • Ophioglossum isanensis
  • Ophioglossum malviae
  • Ophioglossum raphaelianum
• (Haukia)
  • Ophioglossum opacum
  • Ophioglossum tuberosum
• (Ophioglossum) s.s.
  • Ophioglossum ammophilum – sometimes included in O. gomezianum
  • Ophioglossum azoricum
  • Ophioglossum bergianum
  • Ophioglossum caroticaule
  • Ophioglossum convexum
  • †Ophioglossum eocenum (Massalongo) Schimper
  • Ophioglossum fernandezianum – doubtful species
    • • Ophioglossum × giovanninii Ophioglossum gracile – may be included in O. gramineum
  • Ophioglossum gracillimum
  • †Ophioglossum granulatum Heer
  • Ophioglossum harrisii
  • Ophioglossum jaykrishnae – provisionally accepted name
  • Ophioglossum latifolium
  • Ophioglossum lineare – possibly a synonym of O. parvifolium
  • Ophioglossum louisii
  • Ophioglossum loureirianum Presl
  • Ophioglossum lusitanicum
  • Ophioglossum melipillense
  • Ophioglossum oblongum
  • †Ophioglossum ornatum Faddeeva
    • • • • Ophioglossum × pierinii Ophioglossum × pseudoazoricum Ophioglossum richardsiae Burrows
  • †Ophioglossum senomanicum Chlonova
  • Ophioglossum sandieae
  • Ophioglossum scariosum
  • Ophioglossum thomasii
  • Ophioglossum yongrenense

Species that may be placed in this genus include:^[7]

• Ophioglossum falcatum = Ophioderma falcatum
• Ophioglossum intermedium = Ophioderma intermedium
• Ophioglossum simplex = Ophioderma simplex

External links

• Flora of North America: Ophioglossum (Adder's-tongue)

Notes and References

1. http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=122987 eFloras: Ophioglossum
2. 10.1038/s41598-018-24135-2 . Discovery of the World's Smallest Terrestrial Pteridophyte . 2018 . Patel . Mitesh . Reddy . Mandadi Narsimha . Scientific Reports . 8 . 1 . 5911 . 29651115 . 5897345 . 2018NatSR...8.5911P .
3. Lukhtanov . Vladimir . 2015-07-10 . The blue butterfly Polyommatus (Plebicula) atlanticus (Lepidoptera, Lycaenidae) holds the record of the highest number of chromosomes in the non-polyploid eukaryotic organisms . Comparative Cytogenetics . en . 9 . 4 . 683–690 . 10.3897/compcytogen.v9i4.5760 . 4698580 . 26753083 . free .
4. https://bmcplantbiol.biomedcentral.com/articles/10.1186/1471-2229-13-219 Genome size expansion and the relationship between nuclear DNA content and spore size in the Asplenium monanthes fern complex (Aspleniaceae)
5. Nitta . Joel H. . Schuettpelz . Eric . Ramírez-Barahona . Santiago . Iwasaki . Wataru . et al. . 2022 . An Open and Continuously Updated Fern Tree of Life . Frontiers in Plant Science . 13 . 909768. 10.3389/fpls.2022.909768 . 36092417. 9449725. free.
6. Web site: et al. . 2023 . Tree viewer: interactive visualization of FTOL . FTOL v1.6.0 [GenBank release 259] . 27 July 2024.
7. Web site: Hassler . Michael . 2004–2021 . Genus Ophioglossum L. . World Ferns. Synonymic Checklist and Distribution of Ferns and Lycophytes of the World. Version 12.8 . 2021-12-22 .