Rhizome stout, 4-10(-20) × (0.8-)1-1.5(-3) cm, aromatic; roots at lower side of rhizome. Leaves several, mid-green, often reddish at base, ensiform, (60-)70-100(-150) × (0.7-)1-2(-2.5) cm (mostly 1-1.5 cm wide), apex acuminate; midrib conspicuous on both sides. Peduncle compressed triangular, (15-)40-50 cm. Spathe mid-green, leaflike, 30-50 cm, acute. Spadix straight or slightly curved, erect, oblique, narrowly conic to subcylindric (tapering toward apex), 4.5-6.5(-8) × 0.6-1.2(-1.5) cm, densely flowered. Flowers yellowish green, 1.8-2 mm in diam. seen from above; tepals oblong, 2.5-3 × 1-1.2(-1.4) mm, keeled, membranous, apex triangular hooded; filaments oblong, flat, 2-2.5 × 0.3-0.5 mm, anthers cream-colored, 0.4-0.5 mm in diam.; pollen grains ca. 20 µm, exine shallowly and remotely foveolate; gynoecium obconic-cylindric, 2.5-3.5(-4) × (0.8-)1-2.3 mm, with conic, spongy apex and stigma very small. Infructescence 1.5-2 cm in diam., straw-brown at maturity, berries densely arranged. Berry oblong-obovoid, 1- to few seeded, (3.5-)4-4.5 × 2-3(-3.5) mm. Seed oblong-ellipsoid to ovoid, 2.5-3(-4) × 1-1.2(-1.8) mm, without bristles; testa light brown, subsmooth and slightly foveolate. Fl. (Feb-)Apr-Sep. 2n = 24, 36, 48.

Source: [
• 1
]. 

Leaves basally white with pink or red, otherwise bright green; single midvein (secondary midrib) prominently raised above leaf surface, usually somewhat off-center, other veins barely or not raised; cross section rhomboid. Vegetative leaves to 1.75 m; sheathing base (proximal part of leaf) 22.1--66.5(--73.3) cm; distal part of leaf 31.9--95.8(--117.6) ´ 0.5--2 cm, 1.4--1.8 times longer than proximal part of leaf, margins sometimes undulate or crisped. Sympodial leaf (29.9--)34.7--159.1(--183.9) cm, usually shorter than to nearly equal to vegetative leaves; sheathing base 16.1--76.4(--100.1) cm; distal part of leaf 13.5--86.2(--101.2) ´ 0.4--1.9 cm. Spadix (3.8--)4.9--8.9 cm ´ 5.3--10.8 mm at anthesis, post-anthesis spadix 5.5--8.7 cm ´ 6--12.6 mm. Flowers 3--4 mm; pollen grains not staining in aniline blue. Fruits not produced in North America. 2n = 36.

Source: [
• 2
]. 

"Sweetly aromatic; lvs crowded at the base, erect, to 2 m, 8–25 mm wide; scape resembling the lvs, prolonged into an erect green spathe 2–6 dm; spadix 5–10 cm, 1 cm thick at anthesis, 2 cm at maturity, covered with yellowish-brown fls; fr 4–5 × 2 mm; 2n=18, 24, 36, 48. Swamps and shallow water; irregularly circumboreal, in Amer. from N.S. and Que. to Minn., Alta., and e. Wash., s. to Fla., Tex., and Colo. Spring and early summer. (A. americanus)"

Source: [
• 3
]. 

Perennial herb. Strongly pungent aromatic oils present in all parts of plant. Leaves sword-shaped, 0.8-2.0 m long. Spathe leaf-shaped and green like spadix. Spadix appears lateral, green.

Shallow, slow-flowing or stagnant water adjoining streambank edges, swamp areas.

Native to Europe and Asia.

SELECTED REFERENCE

Motley, T. J. 1994. The ethnobotany of sweet flag, Acorus calamus (Araceae). Econ. Bot. 48: 397--412.

Source: [
• 2
].