Gulf Coast Spike Rush

Plants perennial; rhizomes 1–4 mm thick, soft to hard, longer internodes 3–7.5 cm, scales 5 mm, tubers absent. Culms terete or obtusely trigonous, 30–80 cm × 1–5 mm, soft to hard, not septate-nodulose, internally spongy, transverse septa incomplete; plants never forming filiform, flaccid culms. Leaves: distal leaf sheaths persistent, membranous, apex acute to acuminate, often prolonged into a slender awn to 4 mm. Spikelets not proliferous, 14–54 × 3–5.6 mm; rachilla joints without winglike remnants of floral scales; proximal scale empty, amplexicaulous, 2.5–4.9 mm; floral scales 40–180, 2–3 per mm of rachilla, stramineous to pale brown, flanks sometimes minutely dotted reddish, usually with pale to dark brown, reddish, or purplish submarginal band, obovate to suborbicular, widest in middle, 3.4–4.5(–6) × 3–4.8 mm, cartilaginous, membranous toward margins, margins broadly translucent, membranous, apex rounded. Flowers: perianth bristles 6–7, medium brown to pale brown or reddish, slender, proximally slightly flattened, subequal to unequal, mostly exceeding achene, 2–3.4 mm, smooth or sometimes finely retrorsely spinulose; anthers reddish brown, 1.7–2.5 mm; styles 3-fid. Achenes brown, biconvex, obpyriform, 2.2–2.8 × 1.3–1.9 mm, markedly sculptured at 10–15X, each face with (17–)20–24 rows of isodiametric to slightly transversely elongated cells, apex narrowed to a stout, often pale, spongy region 0.8–1.1 mm wide at base, 1/2–3/4 of achene width. Tubercles dark brown, lamelliform to pyramidal, 0.1–0.5 × 0.2–0.5 mm.

Ala., Ark., Fla., Ga., Miss., N.C., S.C., Tex.; Mexico; West Indies; Central America (Nicaragua).

Fruiting late spring–winter.

Brackish to saline marshes, shores, ditches, mostly coastal, often abundant or dominant; 0 (Florida)–600 (Arkansas, Texas)m.

Eleocharis cellulosa Torr. Ann. Lye. N. Y 3 : 298. 1836.
Scirpus dictyospermus C. Wright in Sauv. Anal. Acad. Ci. Habana 8: 79. 1871. (Cuba.)
Culms terete, rarely triangular, 3-7 dm. high, 1-2 mm. wide, straw-colored or greenish ; roots coarse, pale to dark brown; stolons elongated; upper sheaths rigid, oblique, with an elongated mucronate tip, often purplish; lowest sheaths membranous and inflated or leaflike; spikelets cylindric, 1.5-4.5 cm. long, obtuse, thicker than the culm; scales orbicular or obovate, obtuse, 4 mm. long, rigid, striated, straw-colored, with a conspicuous brown border and white, scarious margins, the brown coloration sometimes wanting; style trifid; stamens 3 ; mature achene shining, brown, elliptic to obovate, lenticular, with about 20 rows of quadrangular cells, overlaid by a glass-like surface, merging at the summit into a stout, spongy beak, tipped by the short, dark style-base ; bristles light brown, equaling the achene, involute, without teeth.
Type locality: Bay of St. Louis, Mississippi (Dr. Ingalls).
Distribution : In brackish to saline coastal waters : Cape Hatteras, North Carolina (Fosberg) ; Georgia (Eyles) ; Florida to Texas and northern Mexico ; Bermuda ; West Indies ; Yucatan.