keys to the vascular plants of east texas - Botanical Research ...

ELEOCHARIS/CYPERACEAE
591
43. Scales of spikelets usually acute or subacute
apically; tubercles distinctly wider than tall;
culms hollow with complete transverse
septa 2–4 mm apart (these are evident only
upon internal examination of culm); species
known in East TX only from Guadalupe Co.
at s margin of area _______________________ E. ravenelii
Eleocharis acicularis (L.) Roem. & Schult., (needle-shaped), NEEDLE SPIKE-RUSH, SLENDER SPIKE-
RUSH, LEAST SPIKE-RUSH. Small perennial often forming mats, with hair-like rhizomes; culms 2–
23(–60) cm tall, rounded to slightly flattened, usually with 4–12 angles or ridges; distal leaf
sheath apex membranous, nearly truncate to angled on one side to a broad point; spikelets usually
2–6 mm long, ovoid to lanceoloid or subcylindric, usually with 5–15 scales (and thus flowers);
achenes bluntly trigonous, 0.7–1.1 mm long, with a number of distinct ribs or ridges running
lengthwise and many fine horizontal lines between the ribs, usually pearly white;
tubercle small, 0.2 mm or less long. Damp soils, often on receding shorelines, sometimes submerged;
Henderson, Leon (BRIT), Bastrop, Bexar, Fannin, Gonzales, San Jacinto, Travis, and
Walker (Turner et al. 2003) cos.; scattered in TX; throughout Canada and the U.S. May–Aug,
sporadically to Oct. [E. acicularis var. gracilescens Svenson, E. acicularis var. porcata S.G. Sm.; E.
acicularis var. submersa (Nilsson) Svenson] This species is reported to be “able to grow in acidic
runoff from Appalachian coal mines and flourish in streams with pH as low as 2.8” (Tucker 1987).
Yatskievych (1999) reported that mats of this species “can grow so densely as to inhibit the establishment
of other aquatic species. …” “It is abundant and ecologically important throughout much
of its range” (Smith et al. 2002). Smith et al. (2002) also noted that “Submerged, usually nonflowering
plants are abundant throughout much of the range of the species.” The variant, sometimes
recognized as E. acicularis var. porcata, is sometimes mistaken for E. wolfii (Smith 2001, 2002d).
Eleocharis albida Torr., (white), WHITE SPIKE-RUSH. Rhizomatous perennial forming mats; culms
40 cm or less tall; distal leaf sheath apex light-colored marginally, angled to a point on one side,
but without an abrupt tooth; spikelets 4–12 mm long, oblong to oblong-subcylindric, with 20–
100 scales; achenes trigonous, 0.8–1 mm long, ripening dark brown; tubercles 0.2–0.3 mm long.
Marshes, ditches, other wet areas; Hardin Co. (Turner et al. 2003); mainly Gulf Prairies and
Marshes; se U.S. from MD s to FL w to TX, also NM. Summer.
Eleocharis atropurpurea (Retz.) J. Presl & C. Presl, (dark purple), PURPLE SPIKE-RUSH. Tufted annual;
culms 2–15(–25) cm tall; distal leaf sheath apex angled on one side to a point; spikelets 2–
6(–8) mm long, ellipsoid to lance-ovoid, with (10–)40–80(–100) scales; achenes biconvex, 0.3–
0.6 mm long, dark reddish black to black at maturity; tubercle tiny, 0.2 mm or less long,
perched on summit of achene. Lake and pond margins, ditches, and other wet areas; Bastrop,
DeWitt, Hays, and Montgomery (Turner et al. 2003) cos.; sparsely scattered elsewhere in TX; sw
Canada and widely scattered in the U.S. Jun–Sep. [Scirpus atropurpureus Retz.]
Eleocharis baldwinii (Torr.) Chapm., (for its discoverer, William Baldwin, 1779–1819, Pennsylvania
botanist and physician), BALDWIN’S SPIKE-RUSH. Delicate tufted annual or perennial [?],
stoloniferous, mat-forming; culms thread-like, 3–20(–30) cm tall, often arching; distal leaf
sheath apex angled on one side to a broad point; spikelets flattish, 2–7 mm long, with few (2–
4(–9)) scales, the spikelets often proliferating vegetatively; pistillate spikelets often present at
base of plant; scales of spikelets � 2-ranked, folded along the midrib and thus boat-like;
achenes trigonous, ca. 0.5–0.9 mm long, whitish buffy to olive, grayish olive, or brownish olive;
tubercle conic-subulate, 0.2–0.3(–0.4) mm long. Submerged to emergent in lakes, ponds, or
other wet areas; scattered in East TX; se U.S. from NC s to FL w to AR and TX. End of Apr–Oct.
[E. capillacea of authors, not Kunth]