Ophioglossum nudicaule

Ophioglossum nudicaule L.
(Latin: nudus, bare, naked, and caulis, stem, in reference to the stalk of the fertile portion which appears “leafless” [i.e., naked] because the blade portion usually arises at or near its base— Thieret 1980)

Local names: slender adder’s-tongue, least adder’s-tongue

Plant to ca. 12 cm tall, variable, ranging from very small-leaved forms to large-leaved forms; leaves (blade portion and fertile portion combined) commonly 2–3 per stem; blade portion to 4.5 cm long and 1.7 cm wide but often very small (less than 4 mm long and 3 mm wide), green, dull, the largest with pale central band, flat or nearly so when alive, apically with short apiculum; fertile stalk 2–6 times as long as blade portion, arising at or near ground level; sporangia 5–12 on each side of fertile stalk; 2n = 240 (Mickel & Smith 2004). Disturbed places (e.g., cemeteries, mowed areas around motels), ditches, grassy slopes, wet meadows, damp depressions in pinelands, moist open woods, bog margins; Shelby Co. (Thomas 27493, 16 Feb 1972—BRIT, according to R.D. Thomas’ annotation this is actually the first TX collection given that the Cory 52663 sheet at BRIT, originally thought to be the first TX collection, is actually O. petiolatum) near the LA border, also Hardin (BRIT), Orange, San Augustine (Thomas 1979), and San Jacinto (E. Keith, pers. comm., BAYLU) cos. in the Pineywoods, surprisingly disjunct to Gillespie Co. (O’Kennon 11355, BRIT, Bear Mt., wet area below granite outcrop, growing with O. crotalophoroides) in Central Mineral Region of the Edwards Plateau; se U.S. from VA s to FL w to OK and TX; also Mexico and Central America. Leaves appearing in late winter and early spring, sometimes with a second flush of leaves after heavy rains; usually sporulating Dec–Jun. [O. dendroneuron E.P. St. John, O. ellipticum Hook. & Grev., O. mononeuron E.P. St. John, O. nudicaule var. minus Clausen, O. nudicaule var. tenerum (Mett. ex Prantl) Clausen, O. tenerum Mett. ex Prantl] According to Wagner et al. (1984), this is the most variable and taxonomically confused species of Ophioglossum in the se U.S., with a complete transition series from small- to large-leaved (previously called O. ellipticum) forms. All of the specimens we have been able to confirm from TX are of the small-leaved form. Colonies of the small-leaved form typically have the blade portion quite small (less than 0.4 cm long and 0.3 cm wide), while those of the large-leaved form can have much larger blade portions. The large-leaved form has bireticulate veins (areoles enclosing secondary areoles), but the areoles are “coarser and more open” than those in O. englemannii and O. polyphyllum (Zech et al. 1998). Nelson (2000) commented that, “The combination of small leaf size (leaves generally less than about 1.5 cm long), flat leaves with netted venation, leaves arising at the base of the plant, and non-bulbous stem distinguishes this species from others in the genus.” Wagner and Wagner (1993) pointed out that although this species “is much less common than O. crotalophoroides,” the two “often occur together and are found in the same or similar habitats.” Ophioglossum nudicaule is a striking example of a species that is known in East TX and disjunct to the Central Mineral Region of the Edwards Plateau. Other pteridophytes with similar distribution patterns are Isoëtes butleri (butler’s quillwort), O. crotalophoroides (bulbous adder’s-tongue), and Onoclea sensibilis (sensitive fern).

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