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

598 CYPERACEAE/ELEOCHARIS
Eleocharis microcarpa Torr., (small-fruited), SMALL-FRUIT SPIKE-RUSH, SMALL-SEED SPIKE-RUSH.
Tufted annual; culms thread-like, (2–)10–40 cm tall; distal leaf sheath apex translucent, angled
on one side to a rather long point; spikelets ca. 1.5–5(–10) mm long, sometimes proliferating vegetatively,
lanceoloid to ellipsoid to ovoid, with lowermost scale different from other scales, usually
longer and often resembling an involucral bract, subacute to acute; achenes trigonous to
subterete, 0.5–0.8 mm long, pearly white to pale greenish gray or pale brown, sometimes with
mottling or streaking; tubercle tiny, 0.1–0.3 mm long, perched on summit of achene and not
covering most of it. Savannahs, ditches, shores of lakes, other wet areas; widespread in
Pineywoods and Post Oak Savannah; also n Gulf Prairies and Marshes; e U.S. w to MI and TX.
Apr–Nov. [E. microcarpa var. filiculmis Torr., E. torreyana Boeck.] Bruhl and Smith (2002) recognized
two varieties in this species, and separated them as follows. According to Bruhl and Smith
(2002), all TX plants are in var. filiculmis.
1. Perianth bristles 0.2–0.4 mm, shorter than achene; proximal scale of spikelets 0.4–0.5 mm wide
_____________________________________________________________________________ var. microcarpa
1. Perianth bristles 0.6–1 mm, as long as achene; proximal scale of spikelets 0.8–1 mm wide _______ var. filiculmis
Eleocharis minima Kunth, (least, smallest), SMALL SPIKE-RUSH. Tufted annual, stoloniferous,
forming mats; culms 3–7(–13) cm tall; distal leaf sheath apex translucent, angled on one side to
a rather long-pointed apex; spikelets 2–5(–7) mm long, ovoid or ellipsoid, with (4–)10–28 scales,
compressed laterally when young, becoming terete with age, sometimes proliferating vegetatively;
achenes trigonous, 0.6–0.8 mm long, greenish to pale or reddish brown, often spotted;
tubercle covering most of summit of achene, 0.1–0.3 mm long. Shallow water, lake shores and
other wet areas; Henderson, Smith (BRIT), Bastrop, Marion, Newton, and Rusk (Turner et al.
2003) cos.; also Gulf Prairies and Marshes; FL, MD, and TX. Apr–Oct. [E. minima var. ambigua
(Steud.) Kük., Isolepis ambigua Steud.] Bruhl and Smith (2002) noted that this species is sometimes
confused with E. baldwinii.
Eleocharis montana (Kunth) Roem. & Schult., (pertaining to mountains), MOUNTAIN SPIKE-RUSH.
Rhizomatous perennial, tufted or mat-forming; culms 20–55(–70) cm tall, hollow and completely
and regularly septate with usually externally visible septa ca. 2–5 mm apart; distal leaf
sheath apex truncate or nearly so, with a distinct tooth; spikelets 6–24 mm long, ovoid, with
100 or more small scales only 1–1.5 mm wide; achenes mostly biconvex, 0.7–1.1 mm long; tubercle
0.2–0.35 mm long. Ponds, margins of swamps, ditches, other wet areas; Hardin, Harris,
Jasper, Jefferson, Montgomery (BRIT), Brazos, Liberty, Orange, and Waller (Turner et al. 2003)
cos.; also n Gulf Prairies and Marshes; AL, AR, FL, GA, LA, and TX. Apr–Oct. [E. nodulosa (Roth)
Schult., E. montana var. nodulosa (Roth) Svenson, Scirpus montana Kunth] This species is similar
to E. ravenelii (which usually has trigonous achenes), and according to Smith (2002d), “The
taxonomy of the septate-culmed species … Eleocharis montana and E. ravenelii should be evaluated.”
Intermediates are also known between E. montana and E. montevidensis (Smith 2002d).
Eleocharis montevidensis Kunth, (of Montevideo, Uruguay, where the type was collected), SAND
SPIKE-RUSH. Rhizomatous perennial 10–50 cm tall; distal leaf sheath apex with a red or brown
margin, � perpendicular to culm, with an abrupt awl-shaped tooth on one side; spikelets 3–14
mm long, variable in shape, ovoid to ellipsoid to subcylindric or lanceoloid, with 24–70(–110)
scales; scales broadly rounded apically (sometimes split and thus apparently notched), usually
wrinkled and recurved; achenes subtrigonous, 0.7–1.2 mm long, dark brown to almost blackish;
tubercle � conic, 0.3 mm or less long. Low ground, sandy or clay soils; widespread nearly
throughout TX; s part of the U.S. from NC to CA. Late Mar–early Jul. [E. arenicola Torr., E.
montana (Kunth) Roem. & Schult. subsp. montevidensis (Kunth) Osten, E. palmeri Svenson]
According to Smith (2002d), the name E. montana was for many years misapplied to E.
montevidensis.