Cylinder Spike Rush

Eleocharis cylindrica is synonymous with E. spegazzinii Barros, which was described from temperate South America (E. R. Guaglianone and O. Ueno 1990). It is very uncommon in North America, where it has been confirmed from Aransas, Burnet, and Cameron counties in Texas; reports from Lubbock and Presidio counties have not been confirmed. The report from New Mexico cannot be confirmed because the specimens lack achenes.

Plants perennial; rhizomes evident, 1 mm thick, firm, cortex unknown, internodes unknown, scales fugacious, 5 mm, membranous. Culms terete, often with a few blunt ridges when dry, 20–50 cm × 0.2–0.7 mm, soft, spongy. Leaves: distal leaf sheaths persistent, not splitting, proximally red or stramineous, distally green, membranous, apex usually reddish, subtruncate to obtuse, not callose, tooth present, to 0.4 mm. Spikelets narrowly lanceoloid, narrowly ovoid, or narrowly cylindric, 4–10 × 1–1.5 mm, apex narrowly acute; proximal scale amplexicaulous or clasping 3/4 of culm, entire; subproximal scale empty or with flower; floral scales spreading in fruit, 20–80, 5–6 per mm of rachilla, orange-brown, midrib regions stramineous, narrowly ovate-lanceolate, 1.5–2 × 0.8 mm, entire, apex acute, not carinate. Flowers: perianth bristles 3–6, stramineous, stout, unequal, rudimentary to less than 1/2 achene length; stamens 3; anthers stramineous, 0.7–1.4 mm; styles 3-fid. Achenes falling with scales, stramineous, ellipsoid, compressed-trigonous, angles prominent (keeled), 0.6–0.65 × 0.4–0.45 mm, base narrowed, neck long, smooth at 40X. Tubercles brown, pyramidal, as high as wide to greatly depressed, 0.1–0.25 × 0.15–0.2 mm.

Tex.; South America (Argentina, Paraguay).

Fruiting spring–summer.

Ephemeral pools in old rock quarry; 300m.

Eleocharis texana Britton

Eleocharis cylindrica Buckl. Proc. Acad. Phila 1862: 10. 1862.
Culms erect from a slender, ligneous rhizome, filiform, 2-3 dm. high, sulcate and angled ; sheaths stramineous to light brown, truncate at the apex and conspicuously subulate-toothed ; spikelets linear-cylindric, many-flowered, acute, 8-17 mm. long, not exceeding 2 mm. in width; scales lanceolate, acute, chestnut-brown, not strongly keeled, the scarious margins inrolled at maturity; stamens 3, the anthers 0.7 mm. long; style trifid; body of the achene 0.8 mm. long, dark brown, obovate, smooth to faintly reticulate, trigonous with sharply costate angles, conspicuously narrowed at the apex; style-base light brown, pyramidal, a little wider than the constricted apex of the achene; bristles slender, brown, much shorter than the achene.
Type locality: Northern Texas {Buckley).
Distribution : Texas and New Mexico.