Bolboschoenus robustus

(Pursh) Soják

Cas. Nár. Mus., Odd. Prír. 141: 63. 1972.

Common names: Seacoast bulrush
Illustrated
Basionym: Scirpus robustus Pursh Fl. Amer. Sept. 1: 56. 1814,
Synonyms: Schoenoplectus robustus (Pursh) M. T. Strong
Treatment appears in FNA Volume 23. Treatment on page 42. Mentioned on page 38, 39, 40, 41, 43.
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Culms 50–150 cm × 4–8 mm. Leaves: sheaths reaching beyond middle of culm, fronts usually convex, papery at mouth, veins reaching margin, or occasionally membranous with veins diverging proximal to apex leaving triangular, veinless area; widest blade 4–12 mm wide. Inflorescences simply branched with 1 or not more than 1/2 of spikelets solitary or in clusters of 2 (–3) on 1–7 rays, rays not exceeding 7 cm; involucral-bracts that surpass inflorescence 2–4, widest bract 2–7 mm wide. Spikelets (1–) 5–25, broadly ovoid to rarely lanceoloid, 10–30 × 6–10 mm, base usually truncate; scales usually tightly imbricate, medium to dark orangebrown, lineolate-spotted at 15X, usually 6–9 × 3–4 mm, papery and nearly opaque, rarely membranous, apex 2-fid, 1 mm deep, awn very stout, 2–3 × 0.5 mm at base. Flowers: perianth bristles not persistent on shed achene or 1–2 weakly attached to shed achene, dark redbrown, 1/2 achene length; anthers brownish orange, 1.5–2.5 mm; styles (2–) 3-fid. Achenes dark to medium brown, obovoid, compressedtrigonous with broadly rounded abaxial angle or sometimes biconvex, 2.7–3.5 × 1.8–2.8 mm, apex truncate to broadly rounded, beak 0.1–0.3 mm, surface glossy, exocarp cells evident at 10–20X; in achene cross-section exocarp 2 times thicker than mesocarp and its cells greatly enlarged, 3 times or more deeper than wide; achene specific gravity much less than water.


Phenology: Fruiting spring–fall (south), summer (north).
Habitat: Brackish to saline coastal (very rarely inland) shores and marshes
Elevation: 0(–100) m

Distribution

V23 58-distribution-map.jpg

Ala., Ark., Calif., Conn., Del., Fla., Ga., La., Maine, Md., Mass., Miss., N.H., N.J., N.Y., N.C., R.I., S.C., Tex., Va., Mexico, South America

Discussion

The only known noncoastal localities of Bolboschoenus robustus are in Arkansas, Louisiana, and southeastern Texas. On the Gulf Coast B. robustus sometimes has a triangular, membranous, veinless area in the mouth of the leaf sheath, which is typical of B. maritimus.

The name Bolboschoenus robustus has been erroneously used for both B. maritimus and B. robustus in most literature on the flora of the Pacific coastal states. Putative hybrids of B. robustus with B. maritimus are common in zones of sympatry; they often have long-lanceolate spikelets. The type of Scirpus maritimus forma agonus Fernald is probably a B. maritimus × B. robustus hybrid. Bolboschoenus novae-angliae is probably derived from B. fluviatilis × B. robustus (J. Browning et al. 1995). Putative B. maritimus × B. robustus hybrids are known from New Brunswick and Nova Scotia, north of the known range of B. robustus (J. Browning et al. 1995).

Selected References

None.

Lower Taxa

None.
... more about "Bolboschoenus robustus"
dark +  and medium brown +
much less than water +
brownish orange +
0.15 cm1.5 mm <br />0.0015 m <br /> (0.25 cm2.5 mm <br />0.0025 m <br />) +
0.27 cm2.7 mm <br />0.0027 m <br /> (0.35 cm3.5 mm <br />0.0035 m <br />) +
1 cm10 mm <br />0.01 m <br /> (?) +
1.8mm;2.8mm +
triangular +
S. Galen Smith +
(Pursh) Soják +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
shortened +
persistent +
Scirpus robustus +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.03 cm0.3 mm <br />3.0e-4 m <br />) +
trigonous +, keeled +, v--shaped +  and flat +
glumaceous +  and foliaceous +
2-ranked +  and arranged +
ascending +  and appressed +
parallel +  and divergent +
terete +, rolled +  and plicate +
Seacoast bulrush +
50 cm500 mm <br />0.5 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
trigonous +
4mm;8mm +
Ala. +, Ark. +, Calif. +, Conn. +, Del. +, Fla. +, Ga. +, La. +, Maine +, Md. +, Mass. +, Miss. +, N.H. +, N.J. +, N.Y. +, N.C. +, R.I. +, S.C. +, Tex. +, Va. +, Mexico +  and South America +
0(–100) m +
3 times or more deeper than wide +  and 2 times thicker than mesocarp and its cells greatly enlarged +
hypogynous +  and subtending +
biconvex +  and trigonous +
Brackish to saline coastal (very rarely inland) shores and marshes +
multi-ranked +, 2-ranked +, 3-ranked +  and alternate +
cauline +  and basal +
curved +  and straight +
slightly longer +
with (1-)3-6(-30) bristles and/or scales +
shorter to slightly +
Fruiting spring–fall (south), summer (north). +
2-3(-4)-carpellate +
3 (?) +  and 1 (?) +
Cas. Nár. Mus., Odd. Prír. +
1 +  and 7 +
adventitious +
opaque +, lineolate-spotted +  and dark orangebrown +
0.6 cm6 mm <br />0.006 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
basal +  and proximal +
glabrescent;puberulent +
2-keeled +
membranous +  and papery +
3mm;4mm +
Illustrated +
0.4 cm4 mm <br />0.004 m <br /> (1 cm10 mm <br />0.01 m <br />) +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +
5 +  and 25 +
broadly ovoid;rarely lanceoloid +
septate +, hollow +  and solid +
compressed +, terete +  and trigonous +
papillate +
(2-)3-fid +
Schoenoplectus robustus +
Bolboschoenus robustus +
Bolboschoenus +
species +
notched +
membranous +
herb +, not +  and cespitose +
4mm +  and 12mm +
0.2 cm2 mm <br />0.002 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +