and Harris cos.), found once on top of Enchanted Rock (Llano Co.), reported 

 by Reverchon from Newton Co. in the Timber Belt; from cen. peninsular Fla. to 

 S.C. and w. to Tex.; also from Mex. to S.A. 



2. Ophioglossum nudicaule L. f. var. tenerum (Prantl) Clausen. Fragile 



adder's tongue. Fig. 9. 



Plants mostly small and inconspicuous, to 12 cm. tall, usually much smaller; 

 rootstock subglobose, less than 5 mm. in diameter; common stalk very short, 

 mostly less than 1 cm. long; sterile blade near base of plant, sessile to somewhat 

 petioled, ovate to elliptic or occasionally somewhat oblanceolate, subobtuse to 

 narrowly acute at apex, to 1.5 cm. long and 8 mm. wide; veins forming rather 

 long irregular areoles without included veinlets; fruiting spike on a very slender 

 elongate weak stalk, much-exceeding the sterile blade, with a sharp tip, to 2 mm. 

 in diameter; sporangia as many as 12 on each side of the rachis. 



On grassy slopes and in wet meadows, damp depressions in pinelands, moist 

 open woods, and on the edge of bogs, rare in Hardin Co. in s.e. Tex.; from Fla. 

 and Ga., w. to Tex.; also Mex. to Arg., the W.I., Sumatra and the Phil. 



3. Ophioglossum petiolatum Hook. Fig. 9. 



Plants 6-21 cm. tall; rootstock short, cylindric, slender, erect, bearing several 

 long fleshy roots and one or usually several fronds during a single growing season, 

 commonly reproducing vegetatively by means of modified long slender roots 

 whose buds give rise to new plants; common stalk 2-9 cm. long; sterile blade 

 sessile or cuneate into a short petiole, inserted toward middle of plant, ovate to 

 ovate-lanceolate or elliptic-ovate, acute at the apex, thin in texture, 1.5-6 cm. 

 long, to about 1.7 cm. wide; veins few, forming large areoles; fertile stalk to 

 9 cm. long; fruiting spike 1-4 cm. long; sporangia 0.5-1 mm. in diameter. 



In moist meadows, damp grassy places, depressions in old inland or coastal 

 dunes, occasionally in moist woodlands and thickets, in Tex. only in Winkler Co. 

 in dunes about 10 mi. n.e. of Kermit, in the Plains Country; in Fla., S.C. and 

 Tex., Mex., the W.I. and n. S.A.; also in tropical Afr., Asia and Oceania, 



4. Ophioglossum Engelmannii Prantl. Limestone adder's-tongue. Fig. 4. 



Plants resembling O. vulgatum, slender to somewhat stout, to 25 cm. tall; root- 

 stock cylindric, erect, producing 2 to 3 or rarely more fronds in a single season, 

 with long brown roots; common stalk to 10 cm. long, mostly below ground; 

 sterile blade sessile or sheathing the stalk of the spike, mostly elliptic, acute and 

 apiculate at apex, to 10 cm. long and 3.5 cm. wide; veins forming wide oblique 

 areoles in which are included secondary veinlets that form secondary areoles; 

 fruiting spike on a slender elongate stalk that is to 10 cm. long, cylindric, apicu- 

 late, to about 3 cm. long and 4 mm. in diameter; sporangia to about 30 on each 

 side of the rachis. O. vulgatum f. Engelmannii (Prantl) Clute. 



Usually found in large colonies in thin black soil on limestone barrens or ledges 

 in seepy areas, rocky woodland slopes, in cedar brakes or in clayey soil along 

 streams, occasionally invading pastures and old fields, rare in Okla., in Tex. gen- 

 erally distributed and rather frequent in the Blackland Prairies, with a few sta- 

 tions in the Timber Belt, uncommon in Ariz. (Cochise and Santa Cruz cos.); from 

 Va. to cen. Fla., w. to s. 111., Kan. and Ariz.; also Mex. 



5. Ophioglossum vulgatum L. Common adder's-tongue. Fig. 9. 



Plants often tall and slender, to about 35 cm. tall; rootstock erect, nearly 

 cylindric, bearing numerous fleshy roots and one to several fronds; common stalk 

 to about 9 cm. long, half or more above ground; sterile blade sessile or sheathing 

 the stalk of the spike, variable in shape, ovate to lanceolate or oblong-elliptic 

 to oblanceolate, subtruncate to narrowly obtuse at the apex, to 12 cm. long and 



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