Northern Water-Plantain is an erect native perennial semi-aquatic plant that has basal leaves and a tall flowering stem.
Leaves: The leaves are all basal, forming a rosette about one foot high. Each leaf is somewhat lance like to ovate, up to 7 inches long and 3 to 4 inches wide, with a long stalk. Veins are parallel, edges are smooth, dark green in color, no hair.
The inflorescence is a tall stalk rising from the rosette, growing up to 3 feet high and with 4 or more whorled sets of side branches. At the base of the whorl are 3 lance-shaped stipules. Side branches have one or more whorls of 3 flowers.
Each flower is 3-parted, about 1/4 to 1/3 inch wide, with 3 white petals that have rounded tips but unevenly cut, 3 green sepals that are only half as long as the petals. The base of the petals inside, have a patch of yellow. There is a central flattened receptacle that is light green. 15 to 20 distinct pistils rise in a ring form from around the receptacle. Six stamens with ovoid anthers are grouped into 3 pairs, and placed between the petals. The styles are curved and short - no longer than the ovary. Pollination is by small flies, bees and beetles.
Seed: Fertile flowers develop into a brown, round, flattened on top, seed head, 4.1 to 7 mm in diameter, with the flattened egg shaped light brown seeds positioned vertically around the central core. Each seed has a small beak.
Habitat: Northern Water Plantain requires wet mucky soil or shallow water but can survive a periodic dry condition. Full sun is best. Too little sun will result in poor to no flowering. The root system is rhizomatous.
Names: The genus, Alisma, is a Greek word for water plant. The species, triviale, is used to describe the 'common' or the 'ordinary.' All three of the native species mentioned below were formerly named as varieties or subspecies with the name of Alisma plantago-aquatica. The reclassification of species names (P. Rubtzoff 1964) reserves the name plantago-aquatica for the Eurasian variety of Water-plantain which is not found in our area nor in North America except for being introduced into Alaska. The author name for the plant classification, ‘Pursh’ refers to Frederick Traugott Pursh (1774-1820) German-American botanist who wrote A Systematic Arrangement and Description of the Plants of North America, and was the botanist who catalogued and described the plants brought back by the exploring expedition of Lewis and Clark. He classified this species in 1814.
Comparisons: There is another water plantain with similar structure, A. subcordatum, but there the flowers are half the size of our species and the sepals are just as long as the petals. A third species is the Narrow-leaved Water-plantain, A. gramineum, but there the leaves are narrow and not confusing with our species.
Above: 1st photo - The inflorescence is a large branched panicle rising above the basal leaves. 2nd photo - Main branches of the panicle grow in whorl from the main stem and subdivide into smaller branches, each with 3 flowers.
Below: Individual flowers have 3 white petals with rounded tips but unevenly cut, 3 green sepals that are only half as long as the petals, 6 stamens grouped into 3 pairs are placed against the petals. The base of the petals has a patch of yellow between a pair of stamens. The receptacle in the center is light green and rising in a ring around it are 15 to 20 pistils.
Below: 1st photo - 3 green sepals that are only half as long as the petals. 2nd photo - The leaves are basal, ovate, with a long stalk.
Below: 1st photo - A basal leaf. 2nd photo - A stem node with panicle branches forming. At the base of the node are 3 lance-shaped bracts. 3rd photo - A branch of the panicle subdividing.
Below: The seed head is flattened on top, somewhat 3-sided. The individual seeds are in a vertical circular arrangement. Note the small beak on the seeds.
Notes: Northern Water Plantain is not indigenous to the Garden, but it is to Hennepin County. Eloise Butler brought in plants from Washburn Park, Minneapolis, on Sept 18, 1909 and from Savage, MN on July 15, 1910. More in 1923 and '24. She used the scientific name in vogue at the time of Alisma plantago-aquatica. (see notes above on name changes). Martha Crone planted more in 1933 and 1948. The plant is widely distributed across North America being absent only from Nunavut and Labrador in Canada and the southern states of the U.S. from Texas east to the Carolinas. Within Minnesota it is found in the majority of counties throughout the state with a number of widely scattered exceptions. Of the 3 species native to Minnesota (see 'comparisons' above), only A. triviale has been found in Hennepin County (2019 DNR census).
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.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"