Ophioglossum

Template:Short description Template:Automatic taxobox Ophioglossum, the adder's-tongue ferns, is a genus of about 50 species of ferns in the family Ophioglossaceae. The genus name comes from Ancient Greek ὄφις (óphis), meaning "snake", and γλῶσσα (glôssa), meaning "tongue".<ref name="efloras">eFloras: Ophioglossum accessed 14 February 2014.</ref> Their cosmopolitan distribution is mainly in tropical and subtropical habitats.<ref name="efloras"/>

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.<ref name="efloras"/>

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.<ref>Template:Cite journal</ref>

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.<ref>Template:Cite journal</ref> The species Ophioglossum reticulatum has the highest number of chromosomes found in any multicellular organism.<ref>Genome size expansion and the relationship between nuclear DNA content and spore size in the Asplenium monanthes fern complex (Aspleniaceae)</ref>

Phylogeny

Phylogeny of Ophioglossum<ref>Template:Cite journal</ref><ref>Template:Cite web</ref> Template:Clade

Unassigned species:<ref name=WF_g32>Template:Cite web</ref> Template:Div col

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

Species that may be placed in this genus include:<ref name=WF_g32/>

• Ophioglossum falcatum Template:Au = Ophioderma falcatum
• Ophioglossum intermedium Template:Au = Ophioderma intermedium
• Ophioglossum simplex Template:Au = Ophioderma simplex

External links

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