It is a rhizomatous, beardless perennial plant, native to the Great Lakes region of eastern North America.

It has lavender blue or violet-blue flowers, a very short stem and long fan-like green leaves.

[9][17] They are falcate (sickle-shaped) or sword-shaped,[8][15] and linear,[18] and 4–6 cm (2–2 in) long and 10–8 mm wide.

[9][11] It has green spathes (leaves of the flower bud), which are slightly keeled, and 3–4.5 cm (1–2 in) long.

[9] The short stems have 1 to 2 flowers,[7][9][15] in Spring,[5][20][21] or summer (in Europe),[5] in April,[13] or May,[3][8][9] or early June,[11][12][18] or July.

[9] The style arm guides bumblebees to the lower section of the sepal, to reach the nectar.

The botanist travelled from Detroit by canoe with French Canadian voyagers and the surveyor for the Michigan Territory.

[7][33][34] An illustration of the iris was published in Wild flowers of the United States by Rickett, plate 11 in 1966.

However, unlike it, Iris lacustris is found only in small areas of the Great Lakes region that have been glacier-free for only 11,000 years.

[28] While it was once thought to be a form of Iris cristata[6] (by William Rickatson Dykes in 1913[10] and other authors), later chromosomal studies confirmed the two were separate species.

[3][5][13][24][33] It is found in Canada[12] within the province of Ontario (on the Bruce Peninsula and Manitoulin Island).

[3][5][8] The majority of iris populations are within 500 m of the shore, but the largest ones can occur up several kilometres away from the lake.

[4][8][9] It also grows on alvar limestone barrens,[16][21] and along shorelines,[25] old beach ridges,[11][19] beside streams,[10] in ditches,[19] on cliffs,[19][25][31] behind open dunes,[8][11][19] or at the edges of coniferous woods (in Canada and Michigan).

[3][14][16][31] Iris lacustris is designated a "vulnerable" threatened species by federal, state and provincial laws throughout its distribution range.

[20] A permit is required for any project (including research, development, and construction) which may "take" or "harm" threatened or endangered species in Michigan.

[7] Like many other irises, most parts of the plant are poisonous (rhizome and leaves), if mistakenly ingested can cause stomach pains and vomiting.

[20] In 1998, Iris lacustris was designated the state wildflower of Michigan,[31][35] where the vast majority of populations exist.