Pale-spike Lobelia is an erect native perennial growing up to 40 inches high on slender unbranched stems. Stems usually have hair, especially in the lower sections and the upper section of the stem shows fine ridges. Some plants may grow as biennials.
The leaves are alternate on the stem, up to 4 inches long, about 3x as long as wide, oblong to lanceolate shaped, with obtuse tips and narrowed at the base to the stem without a stalk. Upper leaves become progressively smaller. The lower basal leaves are more broadly oval and tapering to a short stalk. These are often in tufts in a basal rosette. Leaf margins may be entire, with fringed edges or with widely spaced small teeth. All leaves are thick with one main central rib. Some varieties of the species have surface hair and long marginal hair.
The inflorescence is a terminal spike of stalked flowers (a raceme) with buds dense on the spike, which then elongates as the lower buds begin to open, creating open space between the flowers.
Flowers are 5 parted. The calyx is short with 5 long thin finger-like lobes. The corolla is formed into a tube by 5 white to pale blue united petals. Two petals form an irregular upper lip that stands upright with a deep notch. The other 3 petals form the much larger lower lip which projects forward into 3 spreading spatula shaped lobes. These lobes of the lower lip are longer than the corolla tube and frequently have very fine hair. Where the 3 lower lobes meet in the throat of the corolla they form 2 rounded projections that partially obscure the throat.
Rising upward, between the two lobes of the upper lip, from inside the corolla tube are the five stamens, united around the style. This is a typical presentation in the Lobelia genus. The anther tubes are bluish and tightly appressed around the stigma area of the style. This reproductive structure then bends downward at the tip. There is a small thin linear bract at the base of each flower stalk.
L. spicata is gynodioecious, that is a certain percentage of plants will have sterile male parts and are thus female only. These plants can be determined by papery white anther tubes instead of bluish ones, and smaller flowers. See notes under 'Varieties'.
Seeds form in a 2-celled capsule which does not inflate at flower maturity and 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. Seeds collected in the fall can be planted immediately and let nature do the work over Winter.
Studies have shown the plants that are female only produce more fruit capsules, more seed per capsule and better germinating seeds. This is completely different from the Great Blue Lobelia, L. siphilitica, which also has male sterile plants, where there is no difference in fruit sets.
Varieties: Five varieties are currently listed for L. spicata: var. campanulata, var. leptostachys, var. scaposa, var. hirtella and var. spicata. The later two varieties are found in Minnesota. Differences include amount of hair, flower size, leaf characteristics and plants tend to intergrade where populations meet. A study done by Miller and Stanton-Geddes published in 2007 looked at the frequency of L. spicata plants to have only female flowers and the affect on seed production. That study also determined that plants of var. campanulata are predominantly female. [PDF of Study]
Habitat: Pale-spike Lobelia has a fibrous root system with a small taproot. It is found in the more dry sandy soils of uplands rather than meadows. It does best in full sun with mesic to dry-mesic moisture conditions. Too much water is detrimental. It flowers earlier than the Great Blue Lobelia, L. siphilitica or the Cardinal Flower, L. cardinalis.
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." The species name, spicata, means 'spike bearing' and refers to the tall flower spike. The author name for the plant classification - ‘Lam.’ refers to Jean-Baptiste Lamarck (1744-1829) French naturalist and biologist, an early proponent of evolution who among other things, published the 3 volume Flore francaise. He is best known for his theory of the inheritance of acquired characteristics.
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, list this plant in the Lobeliaceae family whereas USDA still maintains it in the Bellflower family (Campanulaceae). Another reference, Mabberley, places it in Caprifoliaceae.
Comparisons: The two most similar looking species to L. spicata with white flowers are Indian Tobacco, L. inflata. where the flowers are usually on short branches in the inflorescence and the calyx inflates after maturity; second is L. dortmanna, Dortmann's Cardinal Flower where the flowers are similar but the plant roots in shallow waters with the flowering stem emergent - a different habitat entirely. [Photos of both below] Cardinal Flower, L. cardinalis has red flowers and Great Blue Lobelia, L. siphilitica has blue flowers.
Above: The inflorescence elongates as the flowers open from the bottom of the raceme. Drawing Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: The corolla tube opens up into and upper and lower lip. The upper deeply notched into 2 lobes with the reproductive parts rising between the lobes. The lower lip of three lobes is longer than the tube. Note the ridges on the stem.
Below: 1st photo - the blue anther tubes of the stamens are visible tightly surrounding the style on this bisexual flower. 2nd photo - the very short calyx has 5 narrow linear lobes. Note the thin bract under each flower stalk.
Below: 1st photo - the upper stem leaves of this plant are hairy with miniature teeth on the margin. 2nd photo - the leaves of the basal clump have more hair and long marginal hair.
Below: Comparisons - two white flowered Lobelias similar to Pale Spike. 1st photo - Dortmann's Cardinal Flower, L. Dortmanna where the flowers are similar but the plant roots in shallow waters with the flowering stem emergent - a different habitat entirely and the calyx inflates after maturity. Photo ©Corey Raimond, Wisconsin Flora. 2nd photo - Indian Tobacco, l. inflata, where the flowers are usually on short branches in the inflorescence and the calyx inflates after maturity. Photo ©Aaron Carlson, Wisconsin Flora.
Notes: Pale-spike Lobelia first arrived in the Garden on Oct. 18, 1924 when Eloise Butler brought in plants from Wells, MN. She added more in 1925, '27 and '28. Martha Crone planed 20 plants of Pale-spike Lobelia in the Garden in July 1945 and more plantings in 1946, '47, '48, '49 and '50. It was still present in 1951 but was not listed on the 1986 Garden census. In Minnesota it is found in most counties with the exceptions mostly in the more moist northern and northeast part of the state. In North America it is found in the Eastern half of the continent except Florida in the U.S. and Labrador and Newfoundland in Canada.
There are 6 Lobelia species found in the wild in Minnesota: L. cardinalis, Cardinal Flower; L. siphilitica, Great Blue Lobelia; L. inflata, Indian-tobacco; L. kalmii, Ontario lobelia; L. dortmanna, Dortmann's Cardinal Flower and L. spicata, Pale-spike Lobelia.
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"