Future Plants by Randy Stewart: Acorus / Sweet Flag

Tuesday, August 17, 2010

Acorus / Sweet Flag

A very interesting small group of plants. To many, they appear to be grasses but they are actually more closely related to Arums and Arisaema. They are very beautiful plants for use in water gardens and wet landscapes.

Acorus calamus ( American Sweet Flag )
An attractive, fast growing, rhizomatous wetland plant reaching a maximum size of 6.5 x 7 ( rarely over 4 ) feet, that is native to marshes of much of North America ( from Alaska to Smithers, British Columbia to Lake Athabasca, Alberta to Lake Nipigon, Ontario to Chapleau, Ontario to Nova Scotia; south to Washington to Oklahoma to Louisiana to Georgia ). In the Windsor/Essex County, Ontario region; it is noted as being locally common in southwestern Essex County, Point Pelee and the Lake Erie Islands as well as the Ohio shore during the 1800s. It was also abundant in marshland along the Detroit River at Detroit during that time. It is endangered in MT, GA, P, NJ & NF. Threatened in NWT, NE & OH. Extinct in DE.
The deciduous to evergreen ( depending on climate ) aromatic strap-shaped leaves reach up to 6 feet in height. The leaves ( up to 1 inch wide ) as well as any other part of the plant can be used to make tea. The foliage is usually fully deciduous north of zone 7.
The greenish-yellow flowers, up to 3 inches in length, are borne early summer.
Hardy zones 3 to 8 ( 2 for northeast Alberta seed source ) in full sun to partial shade, this is an excellent plant for lining streams and large ponds. It prefers fertile wet soil and will even grow in shallow water up to 9 inches deep.
Propagation can be from ripe seed planted in a flat of consistently very wet fertile soil, they should be planted to their permanent site when few inches high.
Propagation is also easily done by root division while dormant.
American Sweet Flag is very fast growing and highly productive; up to 2000 pounds of root per acre may be produced each year. Acorus calamus may be grown on upland sites if kept consistently moist to wet.
Some native indian tribes used the root to induce visions. They also chewed the root to reduce fatigue and increase endurance. Chewing a small ( 1 or 2 inch ) pice of root would bring on a sense of well being and increase endurance. If running you would feel like your running above the ground. A larger root ( 10 inches or more ) if eaten would become psychedelic inducing hallucinations or "visions".
The roots can also be used to make root beers and liquors.
Four varieties of Acorus calamus strains exist in nature; diploid, triploid, tetraploid and hexaploid. Diploids do NOT produce the Asarone which is carcinognic in large quantities ( fears over European strains containing it got Acoruscalamus banned as a food additive in the U.S. in 1968 - reported to cause intestinal tumors ). Diploids grow naturally in North America, Mongolia and central Siberia.

* photo taken on Sep 24 2016 in Annapolis, MD

* photo taken on Nov 19 2016 in Annapolis, MD

'Variegatus' ( Variegated Sweet Flag )
Lower growing, only reaching up to 4 x 4 feet, this cultivar is an extremely attractive water plant with vertical foliage that is deep green and variegated strongly with creamy-white vertical bands.
The flowers are small and greenish.
Generally seen growing in water, it can be grown on regular soil as long as kept moist.

* photos taken on Aug 7 2014 in Elkridge, MD

Acoris gramineus ( Japanese Sweet Flag )
A moderate growing, semi-evergreen to evergreen ( zone 8+ ) grass forming a rhizomatous clump up to 20 inches x 3 ( rarely 5 ) feet, that is recommended for moist to wet areas in sun or partial shade where it thrives. It is native to China, Korea, Japan, India and southeast Asia.
The grass-like foliage, up to 20 x 0.5 inches, is mid-green and very narrow. Flowers are rare but include a spadix up to 3 inches in length that sit atop a short spaethe.
Hardy zones 6 to 9 ( 4 & 5 on protected sites ) in full sun to partial shade on fertile, acidic, moist to wet soil. Winter mulch is recommended in zones 4 to 6. It is rarely bothered by pests or disease, spider mites may be discouraged by spraying water on the foliage.

* photo taken on October 17 2010 @ U.S. National Arboretum, D.C.

* photo taken on May 16 2011 in Washington, D.C.

'Minimus Aureus'
Slow growing and very dwarf, reaching a size of just 3 inches x 2 feet in 5 years, eventually wider. It is the only Acorus low enough to use between stepping stones or massed as a lawn substitute.
The foliage is intense golden-yellow at first, turning to bright golden-green.

* photos taken on Oct 17 2014 in Baltimore Co., MD

'Oborozuki'
Bright yellow foliage.

* photos taken on Mar 8 2013 @ Brookside Gardens, Wheaton, MD

* photo taken on May 3 2014 in Columbia, MD

* photo taken @ Smithsonian Inst, Wash., DC on Aug 25 2014

'Ogon'
A semi-evergreen grass forming a clump up to a maximum size of 16 inches tall and 5 feet wide after many years. The very attractive foliage is up to 16 inches in length and is yellow with cream color variegation. Looks great with purple foliage Bugbane and blue leafed Hosta.

* photo taken on June 19 2010 in Columbia, MD

* photo of unknown internet source

* photo taken on Jan 14 2013 in Ellicott City, MD

* photos taken on Mar 8 2013 @ Brookside Gardens, Wheaton, MD

* photo taken on May 3 2014 in Columbia, MD

* photo taken on June 1 2014 @ Maryland Horticulturalist Society, Ellicott City

* photos taken on Aug 17 2014 in Columbia, MD

* photos taken on Oct 1 2014 in Columbia, MD

* photos taken on Mar 18 2017 @ Brookside Gardens, Wheaton, MD

* photos taken on June 30 2019 in Ellicott City, MD

* photo taken on Nov 10 2020 @ Brookside Gardens, Wheaton, MD

* photo taken on Sep 29 2022 in Columbia, MD

* photo taken on Mar 17 2023 in Columbia, MD

* photo taken on Dec 15 2023 in Clarksville, MD

'Variegatus' ( White Striped Japanese Sweet Flag )
Forms an attractive rhizomatous, semi-evergreen clump up to 1.5 x 2 feet or more, with foliage up to 12 x 0.3 inches, that is green and vertically striped creamy-white.
Needs moist soil.

* photo taken on April 6 2010 in Columbia, MD