Ophioglossum engelmannii

Ophioglossum engelmannii Prantl
(for George Engelmann, 1809–1884, German-born American botanist, “who first recognized the plant as distinct”—Nelson 2000)

Local names: limestone adder’s-tongue, Engelmann’s adder’s-tongue

Plant to 25 cm tall; leaves (blade portion and fertile portion combined) 1–2 per stem; blade portion to 10 cm long and 4.5 cm wide, broadly ovate to narrowly ovate, elliptic, or oblong, commonly folded when alive, apically apiculate, when dried uniformly pale green without pale central band, dull, principal veins of blade forming large primary areoles within which are numerous secondary areoles; fertile stalk 1.3–2.5 times as long as blade portion; sporangia 20–40 on each side of fertile stalk. Usually in thin black soils on limestone, wooded rocky slopes; Pineywoods and Gulf Prairies and Marshes w to West Cross Timbers (e.g., Brown Co., E.J. Palmer 11432, 1917, photocopy of MO sheet at HPC), also e Edwards Plateau, and disjunct to Bailey Co. in the Panhandle (T.C. Rosson 1480B, BRIT); e U.S. from PA s to FL w to NE, AR, and TX and in the sw to NM and AZ; also Mexico and Central America. Leaves appearing from early to late spring, often with a second flush of leaves following summer rains; usually sporulating Dec–Jun. Thieret (1980) noted, “The entire plant of this fern has a very distinctive odor by which it can be identified even after 5 years of storage.”

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