Lobelias have a tubular shape corolla splitting into 2-lipped flowers with a 2-lobed upper lip and a 3-lobed lower lip. Stem: The brilliant scarlet Cardinal Flower has the flowers on a tall spike on a sturdy stem, that has ridges and may have hair or be glabrous. It can grow 2 to 5 feet in height and may branch at the inflorescence.
Leaves are lance shaped alternate, toothed; the upper leaves with very fine teeth and stalkless while the lower leaves have more noticeable teeth and a short leaf stalk.
The inflorescence is a flower spike (a raceme) at the top of the stem, The spike can be up to 16 inches long. Flowers bloom from late summer to frost.
Flowers: The corolla is one of the deepest reds in nature; it is upright, 5-parted about 1-1/2 inches long. The 2-lobes of the upper lip flare out laterally, while the 3-lobes of the lower lip hang downward. Five pointed thin fingers grow up from the green calyx along the corolla. Rising between the lobes of the upper lip are 5 stamens united into a red ascending filament tube and surrounding the style; these nod downward at the tip with the style having a two lobed stigma. The upper portion of the filament tube where the anthers are is blue or bluish-gray. A white tube will indicate the plant is staminately sterile. Two of the anthers have white hair at the tips which is visible. A single green bract is subtended from the flower. Flowers are pollinated exclusively by Hummingbirds. Bumblebees will visit the plant but only steal pollen without pollination and they access opening in the side of the corolla tube. (*see ref. at page bottom)
At maturity seeds form in a 2-celled capsule, that opens at the top to disperse seed to the winds allowing the plant to self-seed. Many small seeds are in the capsules. Seeds require 60 days of cold stratification and require light for germination, so they should be surface sown. Seeds collected in the fall can be planted immediately and let nature do the work. Separating and planting the basal rosettes of mature plants will also produce new plants. These rosettes are connected to the rhizomes of the plant and the separation can be done in fall or spring. Stem cuttings can also be propagated. All together, a versatile plant to grow.
Varieties: A number of varieties have been classified over the years but the current trend is that they are all part of a L. cardinalis complex and it is not yet determined that separate varieties let along separate species are warranted. (*Ref note page bottom)
Habitat: Cardinal Flower grows from a rhizomatous and fibrous root system in moist areas - wet to wet mesic - and near stream banks and is found along the small streams in the marsh area of the Woodland Garden. Full sun preferred, partial shade tolerated. Plants are not long-lived. Aggressive plants can crowd it out.
Names: The genus Lobelia is an honorary for the Flemish botanist Matthias de l'Obel (1538-1616), who, when he moved to England as physician to James I, anglicized his name to Matthew Lobel, hence "lobelia." Cardinal Flower is a native of North America that made its way to Europe via early returnees from North America. The common name and the species cardinalis, is a reference to the color of the robes of Cardinals of the Roman Church. The author name for the plant classification - 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. The family name for this plant is changing based on the work of the Angiosperm Phylogeny Group; many sources, including Minnesota authorities at the U of M Herbarium, now list this plant in the Lobeliaceae family whereas USDA still (2020) maintains it in the Bellflower family (Campanulaceae).
Comparisons: The shape and color of the flower will not be confused with any other species. Royal Catchfly, Silene regia, and Maltese Cross, Silene chalcedonica, are also a brilliant red, but the flowers are different shape.
Above: Drawing courtesy USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
Below: Note the green bract at the base of the flower stalk, the delicate fingers of the calyx around the corolla, and also (in 2nd photo) note the downward nodding grayish color reproductive parts of the flower.
Below: 1st photo - A nice stand of Cardinal Flower at the MN Landscape Arboretum. 2nd photo - The root system of Cardinal Flower is a group of rhizomes. New plants form a rosette the first year and bloom the second year. Plants also self-seed.
Below: The two-part seed capsule is filled with 100+ oval tan colored ribbed seeds.
Below: 1st photo - Lower leaves have more prominent teeth and a short stalk. 2nd photo - The stalkless upper leaves, usually smooth or with very fine teeth.
Below: The united stamens and style rise upward in a filament tube with the anthers in the bluish-gray section. Two ventral stamens have whitish hairs and the stigma is two-lipped.
Below: Cardinal Flowers were once more prevalent in the Garden. This scene below is a grouping of them on August 4, 1948. Image from a Kodachrome Slide taken by Martha Crone.
Notes: Eloise Butler first noted Cardinal Flower in the Garden on Sept. 5, 1908 when it bloomed. There have been many additional plantings of this flower over time by the curators. Eloise first planted it in Sept. 1909 with plants brought in from Stony Brook, MA. She obtained plants for the Garden from Gillett's Nursery, Southwick, MA on May 16, 1919, on May 15, 1920, on May 9, 1923; from Stillwater, MN she secured plants in October 1930 and in 1932 she got more to plant near the Mallard Pool. She also recorded planting from seed in September 1929. Martha Crone added more plants in 1933, '34, '35; 36 plants in 1936 and 80 in 1937; seeds in 1943, '44 and '54 and more plants in 1946, '47, '48, and '51. The plant is known to be native to Minnesota just in the counties which border Wisconsin along the St. Croix and Mississippi Rivers from Chisago County south. This does not include Hennepin where the Garden is located but yet EB, as noted above found it in 1908 prior to her planting any; it is possible it came from a seed from a nearby ornamental garden. In North America it is known in Canada from Ontario eastward and in found throughout the lower 48 states except those of the northwest, from the Dakotas westward to the coast.
There are 6 Lobelia species found in the wild in Minnesota: This species plus L. siphilitica, Great Blue Lobelia; L. inflata, Indian-tobacco; L. kalmii, Ontario lobelia; L. spicata, Pale-spike Lobelia, and L. dortmanna, Dortmann's Cardinal Flower.
Eloise Butler Wrote of Cardinal Flower: "For the late-blooming flowers we must turn to the floodplains and meadows still glorious in the white, blue and gold of the moisture-loving asters, gentians, lobelia and sunflowers, tricked out here and there with the deep red of the Cardinal Flower- the purest red found in nature. The brilliant salvia now blooming in the cultivated gardens has a tinge of yellow in its redness, but that cannot be said of the red lobelia known as the Cardinal Flower." Published 24 Sept. 1911, Minneapolis Sunday Tribune.
Lore and Uses: The juice of the plant is milky and acrid. While the boiled roots have been recorded as used to make a tea to cure stomach aches, it is also known that too large a quantity can cause dizziness, irregular pulse and nausea and herbalists have found it best to avoid. The chemicals in the plant are a stimulant to the Vagus Nerve. That did not stop the Europeans from considering its use as a love charm. If you washed the root and touched it to parts of your body it was supposed to work for you, particularly if you were an elderly lady! A safe use found, is to steep in vinegar or in rubbing alcohol to make an excellent liniment for sore muscles (Moore Ref. #29, #30). All Lobelias have these characteristics, but Cardinal Flower is not as potent as Lobelia inflata (Indian Tobacco).
*Ref: Phenetic Analysis of Morphological Variation in the Lobelia cardinalis Complex by Susan Wysocki Thompson and Thomas G. Lammers, 1997, Systematic Botany.
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"