About Acorus calamus var. americanus Raf.
This variety of sweet flag, Acorus calamus var. americanus Raf., is a herbaceous perennial plant that grows up to 2 meters (79 inches) tall. Its leaves resemble those of plants in the iris family, growing in tufts of basal leaves that emerge from a spreading rhizome. The leaves are erect, yellowish-brown, and radical, with pink sheathing at their bases. They are sword-shaped, flat and narrow, tapering to a long, sharp point, and have parallel veins. The leaf edges are smooth, and can be wavy or crimped. Sweet flag can be distinguished from irises and other similar plants by its crimped leaf edges, the fragrant scent it releases when crushed, and the presence of a spadix. Only sweet flag plants growing in water produce flowers. Solid, triangular flower stalks grow from the axils of the outer leaves. A semi-erect spadix emerges from one side of the flower stem. The spadix is solid, cylindrical, tapers at both ends, and measures 5 to 10 cm in length. As with other members of the Araceae family, no covering spathe is present. The spadix is densely packed with tiny greenish-yellow flowers that are sweetly fragrant. Each flower holds six petals and six stamens, enclosed in a six-divided perianth, which surrounds a three-celled, oblong ovary with a sessile stigma. In Europe, this plant flowers for about one month during late spring or early summer, but does not produce fruit. In Asia, it also produces fruit very sparingly, and spreads primarily through rhizome growth, forming large colonies. The fruit is a mucus-filled berry that falls into water when ripe and disperses by floating. The plant has a branched, cylindrical, knobby rhizome roughly the thickness of a human finger, with many coarse fibrous roots growing below it. The rhizome has a brown exterior and a white interior. Sweet flag is native to the Irtysh River valley in Kazakhstan, but has been widely introduced across the world. It grows in wetland habitats, including the edges of small lakes, ponds and rivers, marshes, and swamps. In 1968, the United States Food and Drug Administration banned A. calamus and its derived products (such as its oil) from use as human food or food additives. In 2001, the European Commission issued a ruling recommending a limit of 115 micrograms per day for consumption in food or alcoholic beverages, but did not define a level of safe exposure. While calamus has been ingested and used for its fragrance, it has not been tested through rigorous clinical research. Individual medical reports of toxicity note severe nausea and prolonged vomiting lasting many hours after oral use. Laboratory studies of the plant's extracts indicate other forms of toxicity, caused mainly by the emetic compound β-asarone. Some claims state the plant is psychoactive (hallucinogenic), but all experiments with American calamus have been completely unsuccessful, even experiments using very high dosages up to 300 g of rhizomes. A. calamus has been traded across many cultures for centuries. It has been used in traditional medicine to treat a range of ailments, and its essential oil aroma is used in the perfume industry. Rhizome essence is used to flavor foods, alcoholic beverages, and bitters in Europe, and the plant was once used to make candy. Young stalks shorter than 30 cm (12 in) can be pulled, and their inner stems eaten raw. Rhizomes can be washed, peeled, cut into small pieces, boiled, and simmered in syrup to make candy. Sweet flag has a long history of use in Chinese, Nepalese, and Indian herbal traditions, and is still used in herbalism by the Chipewyan people.
