Tall Bellflower can be either an annual or a biennial, and will successfully reseed itself. It is somewhat taller than the European Bellflower, growing up to 6 feet high, but more commonly in the range of 2 to 4 feet. The main stem is a bit hairy, is usually not branched, slightly angled, and contains a milky sap.
Leaves: Upper leaves are lance shaped narrowly tapered on each end. Lower leaves can be more egg to ovoid shaped tapered at the base to a stalk that is almost half as long as the leaf blade, and abruptly tapered at the top to a long pointed tip. The most upper leaves are stalkless. All leaves have toothed margins and are alternate on the stem. In size the larger lower leaves are up to 6 inches long - 3x as long as wide.
The inflorescence is a tall spike atop the stem or in less frequent cases, on a side stem rising from an upper leaf axil. Between the flowers on the spike are small green leafy bracts, the lower ones resembling small leaves, the upper ones merely thin and pointed.
The flowers are 5-part with a pale blue to violet bell-shaped flower corolla that separates into 5 lobes which appear satiny in sunlight and tend to have curly edges and visually open to a star shape. Each flower has a pale center nectar ring that surrounds a 5-angled, 3-celled ovary from which protrudes a long curved light purple colored style which curves upward, with a 3-lobed stigma at the tip. Five stamens rise within the ring from the base of the ovary. The anthers are yellow and form a spiral shape at maturity. The calyx is green, smooth, and its five long-pointed lobes reflex backward as the flower opens.
Seed: Mature flowers produce a 3-celled seed capsule shaped like a turban or slender top, that is erect, ribbed and opens by the valves at the top. Dispersion is simply by wind shaking the stem. Seeds are light, about 170,000 to the ounce. They should be surface sown and require 30 days of cold stratification for germination.
Habitat: Tall Bellflower grows from a taproot in wet mesic to dry mesic woods and woodland edges where the soil is rich and the sun is partial to light shade.
Names: There is a move afoot to reclassify into the genus Campanulastrum, due to the difference in flower structure with those other plants in Campanula. Many references still place it in Campanula. The Minnesota authorities at the University Herbarium and the USDA have, moved to the new class. Flora of North America has yet to re-publish on the Bellflower family. The old genus name Campanula is derived from the Latin campana, meaning 'little bell', referring to the bell shaped flowers. This bellflower does not have the same shape flower as the others, the petals spread wide into more of a modified bell, almost saucer shape. The new genus, Campanulastrum refers to the modified bell and the spongy nectar ring at the base of the corolla. The species, americanum, is 'of America' to distinguish this species from the European variety.
The author name for the plant classification originally was 'L.' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. In the new genus, the classification is Campanulastrum americanum (L.) Small, where the work of Linnaeus has been amended by 'Small', which refers to John Kunkel Small (1869-1938), American Botanist, first curator of the New York Botanical Garden, best known for Flora of the Southeastern United States.
Comparison: Tall Bellflower blooms in the Woodland Garden and on the back path to the Upland Garden, whereas the European Bellflower (Campanula rapunculoides) blooms in the sunny Upland Garden. European Bellflower has a bell-shaped flower on one side of the stem, rather than the more open style of C. americana where the flowers surround the stem. In the Upland Garden will also be found Bristly Bellflower, C. cervicaria, where the flowers are clustered together at the stem, have longer sepals and do not nod. Two smaller species also have similar bell-shaped flowers but the plants have a much different structure : Harebell, C. rotundifolia, and Marsh Bellflower, C. aparinoides. Comparison photo shown below.
Above: The flower corolla separates into 5 lobes which appear satiny and tend to have curly edges and visually is a star shape. Each flower has a pale center nectar ring and in the center of the ring is the 3-celled ovary from which rises a long curved light purple color protruding style. Drawing from 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 developing flower buds appear in the leaf axils on the upper part of the stem. These leaves remain small when the flowers open.
Below: 1st photo - Note the fringes on the tips of the petals, the spiral form of the mature yellow anthers, the 3-celled ovary in the center and the reflexed green sepals noticeable on the flower on the left. 2nd photo - The lance-shape leaves are stalked with a slight wing on the petiole. Lower leaves may be more egg shape as the photo shows.
Below: A comparison of the five Bellflowers found in the Garden.
Notes: Eloise Butler's records show that she introduced this plant to the Garden in 1907 and 1908 and planted seeds of this species on Oct. 29, 1914. Martha Crone planted seeds in 1943, '44, '51, and '54, and it is listed on her 1951 census of plants in the Garden. Susan Wilkins added plants in 2009. In the wild it is considered native to Minnesota in the counties bordering the Minnesota River and several other counties bordering the St. Croix and Mississippi rivers in the SE. In North America, its range is the eastern half of the U.S. and Ontario in Canada.
There are five species of Campanula found in Minnesota, two of which are introduced: C. americana, Tall Bellflower; C. aparinoides, Marsh Bellflower; C. rotundifolia, Harebell; C. cervicaria, Bristly Bellflower; and C. rapunculoides, European Bellflower. The latter two are the introductions.
Former Curator Martha Crone wrote in The Fringed Gentian™ of July 1955 of "When the spring flowers have faded and before the late summer flowers have come into bloom, when there is little variety in the woodland where shadows are deepest, it is then that the Tall Blue Bellflower is the most conspicuous. It is an annual and has proven quite equal to reproducing itself year after year."
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"