Flower:

Single to a few flowers at the top of the stem and usually also arising from leaf axils on the upper stem. Flowers in the terminal cluster are stalkless or nearly so and those in the axils are stalked. Flowers are mostly ¾ to 1½ inch (18 to 40 mm) long, erect, funnel-shaped with 5 widely spreading, sharply pointed, oval to triangular lobes 1/8 to ¼ inch (3 to 7 mm) long. Between the lobes is connective, pleat-like tissue, ragged on the outer edge. The inner surface of lobes and pleats is bright blue variably covered with whitish to greenish spots; the inner surface to the tube is whitish with green streaks. Inside the tube is a column of pale-tipped stamens and a single style.

Outer surfaces are mostly light green. The calyx cupping the base of the flower is short tubular with four narrow lobes, variable in size but usually shorter than the floral tube, sometimes absent altogether or reduced to stubs.

Leaves and stems:

Leaves are opposite, narrowly lance-elliptic, 3/8 to 1½ inches (1 to 4 cm) long and to 3/8 inch (1 cm) wide, pointed or blunt at the tip, rounded or narrowed at the base, stalkless, toothless, and hairless except for short, stiff hairs around the edges. The lowest leaves are short and broad, becoming longer and proportionately narrower as they ascend the stem, the largest leaves may be around mid-stem. Leaf pairs are at right angles to the pair above and below. Stems are usually multiple from the base, erect to ascending or prostrate but rising at the tip (decumbent), unbranched, typically tinged reddish and are covered in minute, soft hairs.

Fruit:

Fruit is a cylindric capsule ¾ to 1½ inches long, containing numerous small, flat seeds with narrow wings

Notes:

Pleated Gentian is one of the rarer Gentian species in Minnesota, reaching the eastern edge of its range in our western counties. Farther west, it is found in alpine meadows, bog edges and open forests, but here is primarily restricted to moist, saline wetlands and prairie remnants. According to the DNR, its ecological requirements in MN are not well understood but its preferred habitat is forever at risk from agriculture and invasive species. It was listed as a Special Concern species in 1984.

There are two varieties of G. affinis: var. affinis, the most common and present in Minnesota, has flowers mostly ¾ to 1 inch (18 to 30 mm) long, the flower lobes less than ¼ inch (3 to 5 mm) long, and linear calyx lobes; var. ovata, present in the western US, has flowers mostly 1 to 1½ inches (30 to 40 mm) long, floral lobes ¼+ inch (5 to 7 mm) long, and calyx lobes lance-elliptic to linear. While the spotted flowers of G. affinis are distinctive, it may be confused with the more common and very similar Downy Gentian (Gentiana puberulenta), which has larger flowers (1½ to 2+ inches) that are a deeper blue-violet and lack any spotting, and is found in dry, sandy soils.