Contains 6 accepted taxa overall.

Characteristics
Ophioglossum L.
ADDER'S-TONGUE
Classification
OPHIOGLOSSALES
Ophioglossum
Citation
OPHIOGLOSSUM Linnaeus, Sp. Pl. 1062. 1753.
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TYPE: Ophioglossum vulgatum Linnaeus Lectotypified by Smith, Hist. Filicum 367. 1875.
Species
Scientific Name Common Name Herbarium Specimens Status Photos
Ophioglossum crotalophoroides BULBOUS ADDER'S-TONGUE Native FAC (NWPL)
Ophioglossum engelmannii LIMESTONE ADDER'S-TONGUE Native FACU (NWPL)
Ophioglossum nudicaule SLENDER ADDER'S-TONGUE Native FAC (NWPL)
Ophioglossum palmatum HAND FERN Native Endangered-State FAC+ (NWPL)
Ophioglossum pendulum OLD WORLD ADDER'S-TONGUE Not Native
Ophioglossum petiolatum STALKED ADDER'S-TONGUE Native FAC (NWPL)
[Family identification key]
1.  Epiphyte, lax or pendent; sterile leaf simple or palmately lobed
2
1.  Terrestrial, erect; sterile
3
2.  Sterile blade palmately lobed (young leaves sometimes unlobed) (Cheiroglossa)
2.  Sterile blade linear, sometimes forked (Ophioderma)
3.  Stems spheric, cormlike, fleshy, 3-12 mm wide; leaves arising from deep cavity in top of stem; sterile blades usually lying flat on ground, deltate to cordate
3.  Stems upright, 1-5(10) mm wide; leaves arising at top of stem; sterile blades erect to spreading, mostly ovate to lanceolate
4
4.  Sterile blade veins forming only branching or nonbranching, free, included veinlets within larger areoles
4.  Sterile blade veins in larger leaves forming small areoles within larger areoles
5
5.  Roots 0.5-1.5 mm wide; sterile blades often folded, ovate to ovate-lanceolate, to 10 cm long, to 4.5 cm wide; sporophore (including stalk) 1.3-2.5 times as long as sterile blade; dried blades uniformly green without pale central band
5.  Roots 0.2-0.8 mm wide; sterile blades plane, ovate to lanceolate, to 4.5 cm long, to 1.7 cm wide; sporophore (including stalk) 2-6 times length of sterile blade; dried blades commonly with pale central band
Genus Synonyms
Synonym Full Citation Basionym Type
Cheiroglossa Cheiroglossa C. Presl, Suppl. Tent. Pterid. 56. 1845. TYPE: Cheiroglossa palmata (Linnaeus) C. Presl (Ophioglossum palmatum Linnaeus)
Ophioderma Ophioderma (Blume) Endlicher, Gen. Pl. 66. 1836. BASIONYM: Ophioglossum Linnaeus, sect. Ophioderma Blume, Enum. Pl. Javae 2: 259. 1828. TYPE: Ophioderma pendulum (Linnaeus) C. Presl (Ophioglossum pendulum Linnaeus)
Rhizoglossum Rhizoglossum C. Presl, Suppl. Tent. Pterid. 47. 1845. TYPE: Rhizoglossum bergianum (Schlechtendal) C. Presl (Ophioglossum bergianum Schlechtendal)