Ophioglossum nudicaule L. fil.

Ophioglossum nudicaule is much less common than O . crotalophoroides ; they often occur together and are found in the same or similar habitats. The gametophytes of O . nudicaule are typical for the genus (M.R. Mesler et al. 1975). A given colony may be made up of small, medium, or large plants (W.H. Wagner Jr., C. M. Allen, and G.P. Landry 1984).

Roots yellowish to pale brown, to 15 per plant, 0.2-0.8mm diam., proliferous at wide intervals. Stem upright, 0.2-1.2 cm, 1-5 mm diam., commonly 2-3 leaves per stem. Trophophore stalk to 0.8 cm, 0.1-0.2 times length of trophophore blade. Trophophore blade spreading, usually plane when alive, green, dull, largest leaves drying with pale central band, ovate to lanceolate, thin, blades less than 0.4 × 0.3 cm in many colonies but blades large, to 4.5 × 1.7 cm in other colonies, herbaceous, base gradually tapered, apex with short apiculum; venation finely complex-reticulate, areoles with only included veinlets in smaller blades but with numerous secondary areoles in largest blades. Sporophores arising at or near ground level, 2-6 times as long as trophophore; sporangial clusters 0.5-1.5cm, 1.5 mm or less wide, mostly with 5-12 pairs of sporangia, apiculum 0.5-1 mm.

Ala., Ark., Fla., Ga., La., Miss., N.C., Okla., S.C., Tex.; Mexico; West Indies; Central America; South America; Asia; Africa; Pacific Islands.

Leaves appearing in latter half of winter and early spring, sometimes with second flush in same year after heavy rains. Second-growth fields, vacant lots, roadside ditches, and lawns; 0-90m.

Ophioglossum dendroneuron E.P. St.John; O. ellipticum Hooker & Greville; O. mononeuron E.P. St.John

XI

Ophioglossum tenerum Mett.; Prantl, Ber. Deuts
Bot. Ges. 1: 352. 1883.
Ophioglossum pusillum Nutt. Gen. 2 : 248. 1818. Not O. pusillum Raf. 1814.
Plant 1.5-10 cm. high, often in sand; rhizome stout, cylindric or globose, 2-5 mm. long, 1.8-5 mm. thick; roots persistent, fibrous, about 0.5 mm. thick; leaves usually two (1-4) ; commonstalk 0.1-2 cm. long, hypogean ; lamina sessile or short-stalked, mostly plane and nearly horizontal, elliptic to broadly ovate, acute or obtuse below, acute above, usually not apiculate, 0.4-2 cm. long, 0.2-0.9 cm. broad, the basal veins 3-5, the median vein slightly the strongest, emitting one or two branches, the areolae divergent from the median vein, mostly small, short and broad, the largest with several free and anastomosing included veinlets; sporophyl slender, 1.5-8 cm. long, the spike rather slender, 2-12 mm. long, 1-2 mm. thick, apiculate; sporangia 2-18-jugate; spores .03-.04 mm. thick, finelypitted and verrucose.
Type locality : Near Savannah, Georgia. Distribution : South Carolina to Louisiana ; Cuba.

Ophioglossum nudicaule là một loài dương xỉ trong họ Ophioglossaceae. Loài này được L. f. mô tả khoa học đầu tiên năm 1781.