Eleocharis diandra

C. Wright

Bull. Torrey Bot. Club 10: 101. 1883.

IllustratedEndemicConservation concern
Treatment appears in FNA Volume 23. Treatment on page 103. Mentioned on page 63, 101, 104.

Culms often spreading or reclining, 2–25 cm × 0.3–1 mm. Leaves: apex of distal leaf-sheath acute to acuminate, tooth sometimes present, to 0.2 mm. Spikelets ovoid, 2–7 × 1–4 mm, apex subacute; proximal scale either with flower or empty, base encircling 1/2 of culm; floral scales 50–100, 10 per mm of rachilla, orange to purple-brown, ovate, 1–1.5 × 0.8 mm, midrib slightly keeled, apex rounded to acute. Flowers: perianth bristles absent; stamens 2 (–3); anthers yellow, 0.2–0.3 mm; styles 2-fid or some 3-fid. Achenes 0.7–1 × 0.6–0.9 mm. Tubercles deltoid 0.1–0.2 × 0.25–0.45 mm, 1/3–1/2 as high as wide, 1/8–1/4 as high and 3/4–9/10 as wide as achene.


Phenology: Fruiting late summer–fall.
Habitat: Fresh, mostly sandy, shores of large lakes and streams, sometimes slightly tidal
Elevation: 0–100 m

Distribution

V23 154-distribution-map.jpg

Ont., Conn., Mass., N.H., N.Y., Vt.

Discussion

Of conservation concern.

Eleocharis diandra is close to E. ovata and E. aestuum; it probably should be treated as a distinct species (A. Haines 2001). It is apparently adapted to the greatly fluctuating water levels of rivers and large lakes (e.g., Oneida Lake in New York, Lake Champlain in Vermont). I have not seen specimens of E. diandra from Maine, New Jersey, or Pennsylvania, which may be based on specimens of E. aestuum. Specimens from the Lake-of-the-Woods shore in southwest Ontario are like E. diandra; they have floral scales with apices rounded, not acute as in typical E. diandra. The only recent observations of E. diandra are from the Connecticut River in Massachusetts (1985) and Oneida Lake in New York (1968; A. Haines 2001).

Selected References

None.

Lower Taxa

None.
... more about "Eleocharis diandra"
dark-brown +  and stramineous +
0.07 cm0.7 mm <br />7.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
biconvex +
wide;0.6mm;0.9mm +
0.02 cm0.2 mm <br />2.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
not constricted +
S. Galen Smith* +, Jeremy J. Bruhl* +, M. Socorro González-Elizondo* +  and Francis J. Menapace* +
C. Wright +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
shortened +
persistent +
enlarged +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
ascending +  and appressed +
parallel +  and divergent +
terete +, rolled +  and plicate +
2 cm20 mm <br />0.02 m <br /> (25 cm250 mm <br />0.25 m <br />) +
reclining +  and spreading +
0.3mm;1mm +
green +  and stramineous +
Ont. +, Conn. +, Mass. +, N.H. +, N.Y. +  and Vt. +
0–100 m +
orange +  and purple-brown +
0.1 cm1 mm <br />0.001 m <br /> (0.15 cm1.5 mm <br />0.0015 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (?) +
hypogynous +  and subtending +
biconvex +  and trigonous +
Fresh, mostly sandy, shores of large lakes and streams, sometimes slightly tidal +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
flattened +
0 cm0 mm <br />0 m <br /> (6 cm60 mm <br />0.06 m <br />) +
with (1-)3-6(-30) bristles and/or scales +
Fruiting late summer–fall. +
2-3(-4)-carpellate +
3 (?) +  and 1 (?) +
stramineous;medium brown or red brown or blackish brown +
Bull. Torrey Bot. Club +
ascending +  and horizontal +
caudex-like +
0.05 cm0.5 mm <br />5.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
adventitious +
basal +  and proximal +
2-keeled +
cylindric +
Illustrated +, Endemic +  and Conservation concern +
0.2 cm2 mm <br />0.002 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
3-fid +, some +  and 2-fid +
Eleocharis +
Eleocharis diandra +
Eleocharis (sect. Eleogenus) ser. Ovatae +
species +
0 cm0 mm <br />0 m <br /> (0.02 cm0.2 mm <br />2.0e-4 m <br />) +
0.1mm;0.2mm +
1/3 +  and 1/2 +
0.25mm +  and 0.45mm +