Ophioglossum

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".^[3] Their cosmopolitan distribution is mainly in tropical and subtropical habitats.^[3]

Ophioglossum
Ophioglossum vulgatum
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Division:	Polypodiophyta
Class:	Polypodiopsida
Order:	Ophioglossales
Family:	Ophioglossaceae
Subfamily:	Ophioglossoideae
Genus:	Ophioglossum L.[1]
Type species
Ophioglossum vulgatum L.
Species
See text
Synonyms[2]
Cassiopteris H.Karst. Goswamia Zhang & Zhang Haukia Zhang & Zhang †Ophioglossites Massalongo Rhizoglossum Presl non Kylin Whittieria Zhang & Zhang

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.^[3]

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.^[4]

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.^[5] The species Ophioglossum reticulatum has the highest number of chromosomes found in any multicellular organism.^[6]

Phylogeny

Phylogeny of Ophioglossum^[7][8]

Ophioglossum

(Rhizoglossum) O. bergianum Schltdl. Ophioglossum O. polyphyllum A.Braun (Large adder’s tongue) section Aitchisonii (Whittieria) O. engelmannii Prantl (Limestone adder's tongue) (Goswamia) O. trilokinathii B.L.Yadav, Meghvansi, Meena & Gena O. gomezianum Welw. ex A.Braun O. costatum R.Br O. eliminatum Khand. & Goswamy O. nudicaule L.fil. (Slender/least adder’s tongue) O. lusoafricanum Welw. ex Prantl O. lusitanicum L. O. rubellum Welw. ex A.Braun (Haukia) O. crotalophoroides Walter (Bulbous adder's tongue) (Kawamurae) O. parvifolium Hook. & Grev. O. kawamurae Tagawa O. parvum M.Nishida & Kurita (Ophioglossum) O. namegatae M.Nishida & Kurita O. austroasiaticum Nishida O. pusillum Raf. (Northern adder's tongue) O. lancifolium C.Presl O. reticulatum L. (Stalked adder's tongue) O. coriaceum A.Cunn. O. petiolatum Hook. O. gramineum Willd. O. thermale Kom. O. californicum Prantl (California adder's tongue) O. vulgatum L. (Southern adder's tongue) s.s.

s.l.

Unassigned species:^[2]

• (Goswamia)
  • Ophioglossum gujaratensis S.M.Patil et al.
  • Ophioglossum hitkishorei M.Patel & M.N.Reddy
  • Ophioglossum indicum B.L.Yadav & H.K.Goswami
  • Ophioglossum isanensis Petchsri, Li Bing Zhang & Jaruwatt.
  • Ophioglossum malviae M.Patel & M.N.Reddy
  • Ophioglossum raphaelianum Anto et al.
• (Haukia)
  • Ophioglossum opacum R.Br.
  • Ophioglossum tuberosum Hook. & Arn.
• (Ophioglossum) s.s.
  • Ophioglossum ammophilum C.D.Adams – sometimes included in O. gomezianum
  • Ophioglossum azoricum C.Presl
  • Ophioglossum caroticaule J.E.Burrows
  • Ophioglossum convexum J.E.Burrows
  • †Ophioglossum eocenum (Massalongo) Schimper
  • Ophioglossum fernandezianum C.Chr. – doubtful species
  • Ophioglossum × giovanninii Peruzzi, Pierini, Magrini, Marchetti & Viane
  • Ophioglossum gracile J.E.Burrows ex Pocock – may be included in O. gramineum
  • Ophioglossum gracillimum Welw. ex Hook. & Baker
  • †Ophioglossum granulatum Heer
  • Ophioglossum harrisii Underw.
  • Ophioglossum jaykrishnae S.M.Patil, S.K.Patel, Raole & K.S.Rajput – provisionally accepted name
  • Ophioglossum latifolium (Prantl) J.E.Burrows
  • Ophioglossum lineare Schltr. & Brause – possibly a synonym of O. parvifolium
  • Ophioglossum louisii Taton
  • Ophioglossum loureirianum Presl
  • Ophioglossum melipillense J.Rémy
  • Ophioglossum oblongum H.G.Zhou & H.Li
  • †Ophioglossum ornatum Faddeeva
  • Ophioglossum × pierinii Peruzzi, Magrini, Marchetti & Viane
  • Ophioglossum × pseudoazoricum Peruzzi, Pierini, Magrini, Marchetti & Viane
  • Ophioglossum richardsiae Burrows
  • †Ophioglossum senomanicum Chlonova
  • Ophioglossum sandieae J.E.Burrows
  • Ophioglossum scariosum Clausen
  • Ophioglossum thomasii Clausen
  • Ophioglossum yongrenense Ching ex Z.R.He & W.M.Chu

Species that may be placed in this genus include:^[2]

• Ophioglossum falcatum (Presl) Fowler = Ophioderma falcatum
• Ophioglossum intermedium Hook. = Ophioderma intermedium
• Ophioglossum simplex Ridley = Ophioderma simplex