Ophioglossum

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". Their cosmopolitan distribution is mainly in tropical and subtropical habitats.
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.
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.
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.
Phylogeny
Phylogeny of Ophioglossum
Species
, World Ferns listed the following species:
Goswamia
Ophioglossum costatum
Ophioglossum eliminatum – status uncertain
Ophioglossum gomezianum
Ophioglossum gujaratensis
Ophioglossum hitkishorei
Ophioglossum indicum
Ophioglossum isanensis
Ophioglossum malviae
Ophioglossum nudicaule
Ophioglossum raphaelianum
Ophioglossum rubellum
Ophioglossum trilokinathii
Haukia
Ophioglossum crotalophoroides
Ophioglossum opacum
Ophioglossum tuberosum
Whittieria
Ophioglossum engelmannii
Ophioglossum s.s.
Ophioglossum ammophilum – sometimes included in O. gomezianum
Ophioglossum austroasiaticum – possibly a synonym of O. reticulatum
Ophioglossum azoricum
Ophioglossum californicum
Ophioglossum caroticaule
Ophioglossum convexum
Ophioglossum coriaceum
Ophioglossum fernandezianum – doubtful species
Ophioglossum × giovanninii
Ophioglossum gracile – may be included in O. gramineum
Ophioglossum gracillimum
Ophioglossum gramineum
Ophioglossum harrisii
Ophioglossum jaykrishnae – provisionally accepted name
Ophioglossum kawamurae
Ophioglossum lancifolium
Ophioglossum latifolium
Ophioglossum lineare – possibly a synonym of O. parvifolium
Ophioglossum louisii
Ophioglossum lusitanicum
Ophioglossum lusoafricanum
Ophioglossum melipillense
Ophioglossum namegatae – probably a synonym of O. petiolatum
Ophioglossum oblongum
Ophioglossum parvifolium
Ophioglossum parvum
Ophioglossum petiolatum
Ophioglossum × pierinii
Ophioglossum polyphyllum
Ophioglossum × pseudoazoricum
Ophioglossum pusillum
Ophioglossum reticulatum
Ophioglossum sandieae
Ophioglossum scariosum
Ophioglossum thermale
Ophioglossum thomasii
Ophioglossum vulgatum
Ophioglossum yongrenense
Species that may be placed in this genus include:
Ophioglossum bergianum = Rhizoglossum bergianum
Ophioglossum falcatum = Ophioderma falcatum
Ophioglossum intermedium = Ophioderma intermedium
Ophioglossum simplex = Ophioderma simplex
References
External links
Flora of North America: Ophioglossum (Adder's-tongue)
Ophioglossaceae
Fern genera
Taxa named by Carl Linnaeus