Campanula americana L.

Tall Bellflower

Campanula americana plant

Family - Campanulaceae

Habit - Annual or biennial forb, with short taproot.

Stems - Erect or strongly ascending, to 2 m, simple or sparsely branched, sometimes ridged, with milky sap, hollow, glabrous or occasionally hairy toward tips.

Campanula americana stemStem.

Campanula americana sapStem with milky sap.

Leaves - Alternate, short petiolate to sessile, often with winged petioles, lanceolate to oblong-ovate, serrate with minute prickles at apices of teeth, acuminate-attenuate, to 17 cm long, 5 cm wide, sparsely pubescent above and below. Margins short ciliate. Leaves reduced greatly above to foliaceous bracts.

Campanula americana basal leavesVegetative rosette.

Campanula americana leaf1Leaf adaxial.

Campanula americana leaf2Leaf abaxial.

Campanula americana leavesStem leaves.

Inflorescence - Moderately dense spikelike racemes, the flowers solitary or in clusters of 1-3 at each node, the bracts on the upper portion greatly reduced. Flowers typically subtended by 3 foliaceous bracts, the central bracts larger, the lateral bracts small and linear.

Campanula americana inflorescencePortion of inflorescence.

Flowers - Calyx tube 3-4 mm long at flowering, elongating as fruit matures, the lobes 7-12 mm long, 0.8-1.2 mm wide, hairlike to very narrowly triangular, spreading to reflexed, glabrous. Corollas saucer-shaped, the tube 3-4 mm long, the 5 lobes 6-15 mm long, hairy at the tip, blue to purple, usually white toward center, glabrous. Style 12-15 mm long, strongly exserted from the corolla, elongating and becoming S-shaped in open flowers, the stigma 3-lobed. Stamens 5, alternating with corolla lobes. Filaments white, flattened, joined at base, densely pubescent on one side, to 4 mm long. Anthers yellow, spiraling when mature, 5-6 mm long. Style white to lilac, thickened, 5 mm long. Ovary within calyx tube, 3-locular. Placentation axile.

Campanula americana calyxCalyces.

Campanula americana flowerFlower.

Campanula americana flower2Flower and receptive stigma.

Fruits - Capsules 5-12 mm long, 3-4 mm in diameter, obconic, 3-locular, erect or ascending, dehiscing by 3 round pores near the tip; seeds 0.8-1.2 mm long, 0.8-1.0 mm wide, flattened, often with a thin, winglike margin.

Flowering - July - September.

Habitat - Forest openings, streambanks, roadsides, ditches.

Origin - Native to U.S.

Lookalikes - None close.

Other info. - This species is abundant throughout Missouri. Its U.S. distribution includes most of the eastern half of the country, and it also extends into Canada. It is easily identified by its stout, tall habit, blue flowers, and exserted, curved style. It typically grows as a biennial, with vegetative rosettes of broadly ovate leaves overwintering. The plant is popular in cultivation and grows easily from seed. It would make an attractive addition to any garden.

C. americana does not appear to be closely related to other members of the genus, and some authors have segregated it into its own genus, Campanulastrum.

This species produces pollen while the anthers are still enclosed in the unopened bud. The pollen is shed onto the immature style, which is equipped with bristly hairs. After the bud opens, the stamens quickly wither, and the style elongates dramatically and adopts an S-shape. Insects attracted to the nectar near the base of the style become coated with pollen, which they carry to other flowers. The stigma at the apex of the style becomes receptive when its three lobes spread apart.

Campanula americana spiderFlower and friend.

Photographs taken in the Ozark National Scenic Riverways, Shannon County, MO., 7-8-03 (DETenaglia); also in St. Louis County, 8-25-2018 (Kathy Bildner); also at Weldon Spring Conservation Area, St. Charles County, MO, 11-1-2011 and 7-29-2014, and Matson Hill County Park, St. Charles County, MO, 8-16-2015 (SRTurner).