Eleocharis obtusetrigona

(Lindley & Nees) Steudel

Syn. Pl. Glumac. 2: 80. 1855.

Illustrated
Basionym: Limnochloa obtusetrigona Lindley & Nees in C. F. P. von Martius et al., Fl. Bras. 2(1): 100. 1842
Synonyms: E. fistulosa var. obtusetrigona (Lindley & Nees) Barros E. mutata var. obtusetrigona (Lindley & Nees) C. B. Clarke
Treatment appears in FNA Volume 23. Treatment on page 118. Mentioned on page 116, 117, 119, 120.

Plants perennial; rhizomes 3–4 mm thick, soft to hard, longer internodes 3–8 cm, scales more than 1 cm, tubers absent. Culms obscurely 3–5-angled to terete, 40–110 cm × (2–) 3.6–7.5 mm, soft, not septate-nodulose, internally spongy, transverse septa incomplete; plants never forming filiform, flaccid culms. Leaves: distal leaf-sheaths persistent, membranous, apex acute to long-acuminate, sometimes prolonged into a slender bladelike portion to 6 cm. Spikelets not proliferous, 12–43 × 3.5–6 mm; rachilla joints bearing obscure winglike remnants of floral scales; proximal scale without a flower, amplexicaulous, 3.6–7.5 mm; floral scales 30–125, 1–3 per mm of rachilla, greenish to pale-brown, often with pale to dark-brown submarginal band or a subapical darker spot, ovate to oblong, 4.3–5.8 × 2.5–3.3 mm, cartilaginous, often membranous toward margins, margins broadly translucent, membranous, apex rounded to acute. Flowers: perianth bristles 6–7, stramineous, margins and spinules reddish to pale-brown, stout, flattened, subequal, exceeding achene, 2.5–3.2 mm, coarsely retrorsely spinulose; anthers reddish-brown, 1.5–1.9 mm; styles 3-fid or sometimes 2-fid. Achenes pale-brown, biconvex, obpyriform, 1.7–2.3 × 1.2–1.5 mm, clearly sculptured at 10–15X, each face with 10–15 rows of transversely elongated cells, often isodiametric at achene base, apex usually constricted to neck 0.5–0.6 mm wide. Tubercles stramineous, lamelliform to high-pyramidal, 0.8–1.1 × 0.7–0.9 mm.


Phenology: Fruiting spring–fall.
Habitat: Fresh, permanent water in ditches
Elevation: 0–20 m

Distribution

V23 180-distribution-map.jpg

Tex., e Mexico, Central America (Nicaragua), South America

Discussion

In North America Eleocharis obtusetrigona is known from only five collections, two of them originally identified as E. fistulosa (Poiret) Link [= E. acutangula (Roxburgh) Schultes], which is common in Mexico and South America. The original description of E. obtusetrigona is poor and does not clearly distinguish E. obtusangula from E. acutangula. H. K. Svenson (1939) included E. obtusetrigona in E. acutangula, which can be distinguished by its acutely trigonous culms as well as its smaller floral scales and achenes. The tubercles are often spongy as in E. quadrangulata.

Selected References

None.

Lower Taxa

None.

"prolonged" is not a number.

... more about "Eleocharis obtusetrigona"
0.17 cm1.7 mm <br />0.0017 m <br /> (0.23 cm2.3 mm <br />0.0023 m <br />) +
sculptured +
obpyriform;biconvex +
constricted +
1.2mm;1.5mm +
reddish-brown +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.19 cm1.9 mm <br />0.0019 m <br />) +
constricted +
M. Socorro González-Elizondo +
(Lindley & Nees) Steudel +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
shortened +
persistent +
enlarged +
Limnochloa obtusetrigona +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
ascending +  and appressed +
parallel +  and divergent +
terete +, rolled +  and plicate +
enlarged +
0.2 cm2 mm <br />0.002 m <br /> (0.36 cm3.6 mm <br />0.0036 m <br />) +
40 cm400 mm <br />0.4 m <br /> (110 cm1,100 mm <br />1.1 m <br />) +
filiform +, not septate-nodulose +, obscurely 3-5-angled +  and terete +
flaccid;spongy +
3.6mm;7.5mm +
Tex. +, e Mexico +, Central America (Nicaragua) +  and South America +
0–20 m +
greenish +  and pale-brown +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
papery +  and cartilaginous +
subtending +
biconvex +  and trigonous +
Fresh, permanent water in ditches +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
3 cm30 mm <br />0.03 m <br /> (8 cm80 mm <br />0.08 m <br />) +
reddish +  and pale-brown +
4.3mm;5.8mm +
flattened;ovate;oblong +
subequal +
2.5mm +  and 3.3mm +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
distinct +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (?) +  and 0.06 cm0.6 mm <br />6.0e-4 m <br /> (?) +
with (1-)3-6(-30) bristles and/or scales +
Fruiting spring–fall. +
2-3(-4)-carpellate +
3 (?) +  and 1 (?) +
stramineous;medium brown or red brown or blackish brown +
0.36 cm3.6 mm <br />0.0036 m <br /> (0.75 cm7.5 mm <br />0.0075 m <br />) +
Syn. Pl. Glumac. +
ascending +  and horizontal +
caudex-like +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
adventitious +
basal +  and proximal +
2-keeled +
cylindric +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
Illustrated +
1.2 cm12 mm <br />0.012 m <br /> (4.3 cm43 mm <br />0.043 m <br />) +
not proliferous +
terete;cylindric;narrowly ellipsoid +
0.9 cm9 mm <br />0.009 m <br /> (7.5 cm75 mm <br />0.075 m <br />) +
3.5mm;6mm +
reddish +  and pale-brown +
flattened +
subequal +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
1 (?) +  and 3 (?) +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
2-fid +  and 3-fid +
pale +  and dark-brown +
E. fistulosa var. obtusetrigona +  and E. mutata var. obtusetrigona +
Eleocharis obtusetrigona +
Eleocharis subg. Limnochloa +
species +
0.8mm;1.1mm +
lamelliform +  and high-pyramidal +
0.7mm +  and 0.9mm +
stoloniferous +  and rhizomatous +