Cardinal flower provides a splash of bright red along streams and rivers, in bottomland forests, in ditches by roads, and in other wet places. It's a long-blooming Missouri native wildflower.
Cardinal flower is native perennial wildflower in the bellflower family. At first, the stalks are unbranched, but later there are many flowering side branches.
The flowers are in dense racemes, terminal, with slender, leaflike bracts; they arise from the upper leaf axils. Each flower has the typical lobelia shape, with a 2-parted upper lip and a prominent, 3-divided lower lip; to 1 inch long; with protruding stamens; the petals are cardinal-red, rarely vermillion, or very rarely white or pink.
Blooms July–October.
The leaves are alternate, numerous, dark green, to 6 inches long, lance-shaped, and finely toothed.
The fruits are capsules, ribbed lengthwise, with a crown of withered flower parts persisting at the tip.
Similar species: Missouri has five species of Lobelia, but only four are common, and none of the others have red flowers:
- Blue cardinal flower, or great blue lobelia (L. siphilitica), has violet, blue, or lavender flowers.
- Spiked lobelia (L. spicata) has pale blue or white flowers.
- Indian tobacco (L. inflata) is similar to spiked lobelia, but its stems usually branch above the midpoint, and its fruit capsules become greatly inflated as the seeds ripen. It's an aggressive, somewhat weedy plant often found in disturbed areas.
Height: to 5 feet, but usually shorter (2–4 feet).
Scattered nearly statewide, but absent or uncommon in the western part of the Glaciated Plains of northern Missouri. Cultivated statewide.
Habitat and Conservation
Cardinal flower grows in wet places: along rivers and streams, in openings of bottomland forests, ditches, sloughs, swamps, and lakes.
Also found in cultivation, where it prefers rich, humusy, medium to wet soils and partial shade.
Status
Native Missouri wildflower.
Human Connections
Because of its striking red flowers, this species was introduced very early into cultivation in Europe, and it remains popular there and in the United States.
A Missouri native with exceptional landscaping potential, it has been named a Plant of Merit for St. Louis and other regional gardeners. It is recommended for moist or wet areas such as along streams and ponds, in water gardens, and in shaded or wooded gardens with moist soils. Some people grow it just for its foliage in aquariums. It needs constant moisture. Obtain your garden plants from ethical wildflower nurseries; don't dig them from the wild.
As with the bird called the northern cardinal, this flower was named for the red hue that is similar to that of the garments worn by Roman Catholic cardinals.
The genus name, Lobelia, might at first glance seem to be in reference to the lobed petal tubes, but instead it honors the Flemish botanist and physician Matthias de l'Obel (1538–1616). He is famous for describing the distinctions between monocots and dicots: vascular plants whose seeds have only one embryonic leaf (one cotyledon), and vascular plants whose seeds have two embryonic leaves (two cotyledons). Monocots include lilies, orchids, yuccas, irises, grasses, and such, all with parallel leaf veins and flower parts in threes. Dicots (also called eudicots) include most of the other flowering plants you're familiar with (from beans to roses to maple trees), that have branching leaf veins and flower parts in fours or fives. (Lobelias, for the record, would be described as dicots.)
Ecosystem Connections
The red flowers of this species are attractive to ruby-throated hummingbirds, which are probably the major pollinators. Many other bright red flowers are especially attractive to hummingbirds, too, including eastern red columbine, royal catchfly, fire pink, and trumpet honeysuckle.
Butterflies visit the flowers, too.
Cardinal flower and the jumble of other plants that grow in and along streams, ponds, and wetlands create important habitat for a wide variety of animals. With their interconnected network of roots, they hold soils and prevent erosion during floods or heavy rainstorms.
