Sweet Flag

‘Sweet flag’ is found in marshy places and along river banks from (600-) 1000-2000 m. The rootstock is medicinal and yields an oil used in the manufacture of soap, cosmetics and in the liquor industry; it is also medicinal, being used in stomach complaints, snake bite, as an insect repellant, and for remittent fevers.

Acorus calamus, a sterile triploid, was introduced to North America by early European settlers, who grew it for medicinal uses. Rhizomes propagate easily, and the species has spread throughout northeast and central United States. Scattered populations occur elsewhere. Although leaf and spadix size of A. calamus and A. americanus overlap, those measurements differ significantly, with A. calamus in general having longer and wider leaves and longer spadices.

Perennial herb up to 80 cm tall. Rootstock stout, 1-1.5 cm broad, creeping, with long fibrous roots from the lower surface. Stem erect, glabrous, grooved at one side, and ribbed at the opposite. Leaves ensiform or linear, 55-100 x 8-1.5 cm. Spathe leaf-like, up to 46 cm long, not enclosing the spadix. Spadix 5-6.5 cm long, cylindrical, obtuse, 1-1.4 cm broad. Tepals c. 2 mm long, oblong-obovate, slightly curved, margin membranous, surface with embedded raphides. Filaments 2 mm long, flat, anthers less than 1 mm long, ± orbicular. Ovary 3 mm long, obconical; seeds obconical, 2 mm long,

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.

W-E Nepal: Bhutan, China, India, Japan, Sri Lanka; N. Asia, Europe, C. & N. America.

Distribution: N. and C. America, Europe, Asia.

introduced; N.B., N.S., Ont., Que.; Ala., Ark., Calif., Colo., Conn., Del., D.C., Ga., Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Nebr., N.H., N.J., N.Y., N.C., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Vt., Va., W.Va., Wis.; Europe; Asia; Africa; Indian Ocean Islands; Pacific Islands.

100-2300 m

Fl. Per.: June July.

Flowering early spring--early summer.

Wet open areas, marshes, swales, and along edges of quiet water; 0--900m.