Amaranthus cannabinus

(Linnaeus) J. D. Sauer

Madroño 13: 11. 1955.

Common names: Salt-marsh water-hemp tidal-marsh water-hemp water-hemp pigweed
IllustratedEndemic
Basionym: Acnida cannabina Linnaeus Sp. Pl. 2: 1027. 1753
Treatment appears in FNA Volume 4. Treatment on page 416. Mentioned on page 412.

Stems erect, branched, stout, usually 1–3 m. Leaves: petiole 1/2 length of blade; blade lanceolate or narrowly lanceolate to linear, to 20 × 4 cm, base narrowly cuneate, margins entire, plane to slightly undulate, apex acute to acuminate. Inflorescences mostly terminal, narrow spikes or thyrses, usually interrupted, linear. Bracts: of pistillate flowers 1.5 mm; of staminate flowers with midribs not prominent, scarcely excurrent, shorter than 1 mm. Pistillate flowers: tepals absent or 1–2 and rudimentary; style-branches ± erect; stigmas 3–5. Staminate flowers: tepals 5, without prominent midribs, equal, 2.5–3 mm, apex obtuse to indistinctly mucronulate in outer tepals; stamens 3–5. Utricles often black, with 3 (–5) longitudinal ridges corresponding to 3–5 style-branches, ovoid or obovoid, 2.5–4 mm (exceeding tepals, when present), somewhat fleshy, smooth (slightly rugose, especially in herbarium specimens). Seeds reddish-brown to dark-brown, 2–3 mm diam., shiny.


Phenology: Flowering summer–fall.
Habitat: Coastal salt or brackish marshes, edges of sloughs, tidal riverbanks, tidal flats, rarely freshwater semiaquatic habitats
Elevation: 0-50 m

Distribution

Ala., Conn., Del., D.C., Fla., Ga., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Pa., R.I., S.C., Vt., Va.

Discussion

Reports of Amaranthus cannabinus from southern Florida and the Gulf Coastal Plain are the result of misidentifications of A. australis. According to J. D. Sauer (1955), plants of A. cannabinus from northern coastal Atlantic Florida are atypical and probably represent hybrid populations transitional toward A. australis.

Selected References

None.

Lower Taxa

None.
... more about "Amaranthus cannabinus"
Sergei L. Mosyakin +  and Kenneth R. Robertson +
(Linnaeus) J. D. Sauer +
cuneate +
Acnida cannabina +
0 cm0 mm <br />0 m <br /> (20 cm200 mm <br />0.2 m <br />) +
narrowly lanceolate +  and linear +
0cm;4cm +
elliptic to subulate-linear +  and elliptic +
persistent +
triangular +, deltate +, subulate +, linear +, lanceolate +  and ovate +
Salt-marsh water-hemp +, tidal-marsh water-hemp +  and water-hemp pigweed +
Ala. +, Conn. +, Del. +, D.C. +, Fla. +, Ga. +, Maine +, Md. +, Mass. +, N.H. +, N.J. +, N.Y. +, N.C. +, Pa. +, R.I. +, S.C. +, Vt. +  and Va. +
0-50 m +
peripheral +
staminate +  and pistillate +
not enfolding +
minute +  and small +
not +  and dehiscent +
Coastal salt or brackish marshes, edges of sloughs, tidal riverbanks, tidal flats, rarely freshwater semiaquatic habitats +
terminal +  and axillary +
reduced +
plane +  and slightly undulate +
prominent +  and not prominent +
scarious +  and membranaceous +
well-developed +
1/2 length of blade +
Flowering summer–fall. +
rudimentary +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
lenticular +  and subglobose +
Illustrated +  and Endemic +
well-developed +
prostrate +  and decumbent +
100 cm1,000 mm <br />1 m <br /> (300 cm3,000 mm <br />3 m <br />) +
not fleshy +
slender +
0.01 cm0.1 mm <br />1.0e-4 m <br /> (0.1 cm1 mm <br />0.001 m <br />) +
Acnida sect. Acnidastrum +  and Acnida sect. Montelia +
Amaranthus cannabinus +
Amaranthus sect. Acnida +
species +
distinct +
rudimentary +
linear-lanceolate +  and reduced-linear +
subequal +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
indurate +, membranaceous +, chartaceous +  and scarious +
walled +  and 3(-5)-veined +
tuberculate +  and rugose +
obovoid +  and ovoid +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +