Eleocharis robbinsii

Oakes

Mag. Hort. Bot. 7: 178. 1841.

Common names: Robbin’s sppike-rush éléocharide Robbins
IllustratedEndemic
Treatment appears in FNA Volume 23. Treatment on page 117. Mentioned on page 62, 109, 112, 116.

Plants perennial; rhizomes (0.5–) 1–2 mm thick, longer internodes 2–3 cm, scales 5–7 mm; tubers sometimes present, apical, ovoid, 4–8 × 3–4 mm. Culms acutely trigonous; spikelet-bearing culms 16–70 cm × 0.7–0.9 mm; when submersed plants often forming numerous, filiform, flaccid culms without spikelets, sometimes with whorls of slender branches, 0.1–0.3 mm wide; soft, sometimes septate-nodulose when aquatic, internally spongy, transverse septa incomplete. Leaves: distal leaf-sheaths persistent or decaying, membranous, apex obtuse to acuminate. Spikelets sometimes proliferous (when submerged), 9–33 × 1.5–3 mm; rachilla joints bearing prominent winglike remnants of floral scales; proximal scale with a flower, amplexicaulous, (5–) 6–9.8 mm; floral scales 4–18, 0.5–1 per mm of rachilla, stramineous to pale-brown, often minutely dotted reddish, without or rarely with darker submarginal band, narrowly ovate to lanceolate, 5–7.8 × 2–3 mm, thickly papery, membranous toward margins, apex narrowly rounded to acute. Flowers: perianth bristles 6–7, stramineous to reddish-brown, proximally slightly flattened, subequal to equal, much exceeding to rarely shorter than achene, 3–5 mm, retrorsely spinulose; anthers yellow to reddish, 1.6–3.2 mm; styles 3-fid. Achenes stramineous or medium brown, biconvex or compressed trigonous, narrowly obpyriform, 1.9–2.6 × 1–1.4 mm, adaxial face with 15–22 rows of rectangular, transversely elongated or nearly isodiametric cells, clearly sculptured at 10–15X, apex usually conspicuously constricted to short neck 0.4–0.7 mm wide, usually wider at tubercle base. Tubercles stramineous to medium brown, high-pyramidal, 0.5–1.1 × 0.3–0.7 mm.


Phenology: Fruiting late spring–late fall.
Habitat: Shallow waters of fresh lakes and ponds with sandy-peaty soils
Elevation: 10–500 m

Distribution

V23 178-distribution-map.jpg

N.B., N.S., Ont., Que., Ala., Conn., Del., Fla., Ga., Maine, Mass., Mich., Minn., N.H., N.J., N.C., Ohio, S.C., Va., Wis.

Discussion

I have not seen voucher specimens for literature reports of Eleocharis robbinsii from Indiana, Pennsylvania, or Rhode Island. Plants from South Carolina with the achene surface cells nearly isodiametric, the achene apex spongy, and the anthers to 3.2 mm may represent an undescribed taxon.

Selected References

None.

Lower Taxa

None.

"wider" is not a number.

... more about "Eleocharis robbinsii"
brown +, medium +  and stramineous +
0.19 cm1.9 mm <br />0.0019 m <br /> (0.26 cm2.6 mm <br />0.0026 m <br />) +
sculptured +
obpyriform;trigonous;compressed;biconvex +
constricted +
1mm;1.4mm +
yellow;reddish +
0.16 cm1.6 mm <br />0.0016 m <br /> (0.32 cm3.2 mm <br />0.0032 m <br />) +
usually conspicuously constricted +  and short +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
0.3 cm3 mm <br />0.003 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
M. Socorro González-Elizondo +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
shortened +
persistent +
enlarged +
Undefined subg. Limnochloa +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
ascending +  and appressed +
parallel +  and divergent +
terete +, rolled +  and plicate +
rectangular +
enlarged +
Robbin’s sppike-rush +  and éléocharide Robbins +
16 cm160 mm <br />0.16 m <br /> (70 cm700 mm <br />0.7 m <br />) +
septate-nodulose +, filiform +  and trigonous +
spongy;flaccid +
0.7mm;0.9mm +
decaying +  and persistent +
N.B. +, N.S. +, Ont. +, Que. +, Ala. +, Conn. +, Del. +, Fla. +, Ga. +, Maine +, Mass. +, Mich. +, Minn. +, N.H. +, N.J. +, N.C. +, Ohio +, S.C. +, Va. +  and Wis. +
10–500 m +
dotted reddish +, stramineous +  and pale-brown +
0.5 cm5 mm <br />0.005 m <br /> (0.78 cm7.8 mm <br />0.0078 m <br />) +
narrowly ovate +  and lanceolate +
0.3 cm3 mm <br />0.003 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
membranous +  and papery +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
subtending +
biconvex +  and trigonous +
Shallow waters of fresh lakes and ponds with sandy-peaty soils +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
distinct +
0.04 cm0.4 mm <br />4.0e-4 m <br /> (?) +  and 0.07 cm0.7 mm <br />7.0e-4 m <br /> (?) +
0.3 cm3 mm <br />0.003 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
with (1-)3-6(-30) bristles and/or scales +
Fruiting late spring–late fall. +
2-3(-4)-carpellate +
3 (?) +  and 1 (?) +
0.5 cm5 mm <br />0.005 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
stramineous;medium brown or red brown or blackish brown +
0.6 cm6 mm <br />0.006 m <br /> (0.98 cm9.8 mm <br />0.0098 m <br />) +
Mag. Hort. Bot. +
ascending +  and horizontal +
caudex-like +
0.1 cm1 mm <br />0.001 m <br /> (0.2 cm2 mm <br />0.002 m <br />) +
adventitious +
basal +  and proximal +
2-keeled +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
cylindric +
Illustrated +  and Endemic +
0.9 cm9 mm <br />0.009 m <br /> (3.3 cm33 mm <br />0.033 m <br />) +
terete;cylindric;narrowly ellipsoid +
0.9 cm9 mm <br />0.009 m <br /> (7.5 cm75 mm <br />0.075 m <br />) +
1.5mm;3mm +
1 (?) +  and 3 (?) +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
Eleocharis (sect. Undefined) ser. Mutatae +
Eleocharis robbinsii +
Eleocharis subg. Limnochloa +
species +
stramineous;medium brown +
0.5mm;1.1mm +
high-pyramidal +
0.3mm +  and 0.7mm +
stoloniferous +  and rhizomatous +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +