Flower:

Flowers are in a spike-like raceme up to 2 feet long at the top of the main stem. Individual flowers are crimson red, 1 to 1½ inches long, and tubular. The upper lip is split into 2 lobes that spread out sideways; the lower lip is divided into 3 lobes of approximately the same size and shape. A style with a hooked tip rises up between the upper lobes. One plant usually has a single spike and numerous flowers

Leaves and stem:

Leaves are up to 6 inches long and 1½ inches wide, coarsely toothed, usually hairless, tapering to a sharply pointed tip. Leaves near the base of the plant have short leaf stalks, becoming stalkless farther up the plant. Attachment is alternate. The stem is angled and usually hairless.

Fruit:

Fruit is a small capsule, containing many tiny, oval, semi-translucent golden seeds. The surface of the seed is covered in a network of fine ridges and tiny shiny scales.

Notes:

Cardinal Flower is an easy plant to ID—nothing else has this deep red flower color combined with this flower shape. Minnesota is at the western edge of its range; it's found mostly in counties bordering Wisconsin, in the St. Croix River floodplain. There is a good size population of Cardinal Flower in Dakota County southeast of Hastings, where Hwy 68 crosses the Vermillion River on the way to Prairie Island Casino. There are cultivars in the nursery trade with red leaves; the native has green leaves. Hummingbirds love it. The Lobelia genus was once in its own Lobeliaceae family, then was moved to the Campanulaceae (Bellflower) family but is now back in Lobeliaceae.