Marsh Arrowgrass is not a true grass and is not in the grass family, but is a perennial marsh plant found in bog edges as well as calcareous sedge meadows. It grows from rhizomes and dense fibrous roots putting up erect circular stems, up to 17 inches high.
The leaves are basal, rising from a sheath, entire, erect, un-lobed, only 0.78 - 3 mm wide and up to 10 inches long, but not as long as the flowering scape, mostly circular in cross-section, furrowed at the base, and taper to a point.
Inflorescence: The greenish-yellow flowers occur on a raceme-like scape which rises directly from the root and which elongates during flowering to hold as many as 30 to 80 flowers. The scape, which is usually purplish at the base, exceeds the leaves in length.
Flowers are bisexual, with 6 elliptic shaped tepals (petals and sepals combined) which have round tips; these are arranged in two series. Each flower is on a short stalk, has 6 pistils of which 3 are sterile. There are no styles on the pistils but the stigmas are whitish and are the showy parts of the flower. Stamens number 4 or 6 (usually 6 in 2 series - outer and inner) and are attached to the tepals. First the pistils open, then the outer series of stamens and when these fall away, the inner stamens open. The receptacle has wings.
Seed: The seed capsule, a schizocarp, is from 7 to 8.3 mm long and 0.8 to 1.2 mm wide. It has 3 chambers which have an oblong brown seed 6.5 to 8.5 mm long with a beak and 0.5 to 1.5 mm broad, weakly ridged on one side. Flowers are wind pollinated.
Habitat: Marsh Arrowgrass is typically found in marsh areas and moist alkaline meadows in full sun. The rhizomes are stout.
Names: The genus name was placed by Linnaeus. Triglochin is taken from the Greek word glochin and the prefix tri for 3. Possibly he had in mind a Greek name for one of the species of this genus and the tri referring to the 3 parted receptacle that some of the species of the genus have. The species name palustris means 'marsh loving'. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: There are only two species of the Juncaginaceae family represented in Minnesota, T. palustris and T. maritima, Seaside Arrowgrass. The latter has 6 fertile pistils and a receptacle without wings. It is found in many of the same counties as T. palustris.
Above: 1st photo - Note the stem almost twice as tall as the leaves. 2nd photo - Flower detail of Marsh Arrowgrass. The showy whitish parts are the stigmas of the pistils. 3rd photo - Seed capsules held upright against the stem prior to the release of seeds. All photos and photo upper left ©Hugh Iltis, Wisconsin Flora.
Below: Drawing of Marsh Arrowgrass from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Botanical illustration courtesy of Kurt Steüber's Online Library.
Notes: Marsh Arrowgrass is considered indigenous to the Garden. Eloise Butler catalogued it in her early Garden records and in reports to the Park Board. On June 12, 1916 she reported planting it. She only gave the genus name but recorded the source as in "the vicinity of Savage" which could make it Marsh Arrowgrass or Seaside Arrowgrass as both species are found in that area. T. maritima, Seaside arrowgrass, was however planted in the Garden on July 14, 1933 by Martha Crone, with plants obtained from Gertrude Gram's Garden. That species is no longer extant in the Garden.
Marsh Arrowgrass is found throughout North America except the warm, humid SE quadrant of the the U. S. (from Texas-Nebraska east to Virginia-Florida). In Minnesota today, it is found in 33 widely scattered counties, mostly located in the upper 1/3 and the lower 1/3 of the State. It is no longer considered extant in Hennepin County where the Garden is located, but is found in several neighboring counties. T. maritima, Seaside arrowgrass is also found in Minnesota and in more places. In addition, there are two other species of Triglochin found in North America. Marsh Arrowgrass is also found in the British Isles and parts of northern Eurasia.
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"