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.
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.
"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)"
