Great blue lobelia

Overview

Great blue lobelia is an herbaceous perennial in the bellflower (Campanulaceae) family. It is native to the United States and southern Canada from Nova Scotia to South Carolina, west to Manitoba, eastern Colorado, and Louisiana. It is common in Minnesota.

Great blue lobelia is found in wet to moist habitats, including meadows, swamps, fens, and bottomland forests, at the edges of lakes and ponds, on streambanks and riverbanks, and on roadsides. It grows under partial shade to full sun in wet to moist, fertile, loamy soil.

Great blue lobelia is a popular garden plant. It is easy to grow and is tolerant of a variety of soils and conditions.

Great blue lobelia is a poisonous plant. All parts of the plant are toxic if eaten. Symptoms of poisoning include nausea, vomiting, diarrhea, salivation, exhaustion and weakness, dilation of pupils, convulsions, and coma.

Description

Great blue lobelia is a 12″ to 48″ tall, erect or strongly ascending, perennial forb that rises on a single stem from a taproot.

The stem is erect, unbranched, and hairless or sparsely hairy.

The leaves are alternate, lance-shaped to elliptical, 2 to 6 inches (5-15 cm) long, and 0.5 to 1.5 inches (1.2-3.8 cm) wide. They are dark green in color and have a slightly toothed margin.

The inflorescence is an unbranched, spike-like cluster of 6 to 60 showy blue flowers at the end of the stem.

Each flower is ⅝″ to 1¼″ long and about ½″ wide. The corolla is tube shaped with a long, three-lobed lower lip and a short, two-lobed upper lip. The lower lobe is sometimes striped.

The fruit is a capsule with many small seeds.

Distribution

Sources

2, 3, 5, 7, 28, 30, 83.

Biodiversity occurrence data published by: Minnesota Biodiversity Atlas (accessed through the Minnesota Biodiversity Atlas Portal, bellatlas.umn.edu. Accessed 9/16/2026).

Midwest Herbaria Portal. 2026. https://midwestherbaria.org/portal/index.php. Accessed 9/16/2026.

Lobelia siphilitica L. in Bánki, O., Roskov, Y., Döring, M., Ower, G., Hernández Robles, D. R., Plata Corredor, C. A., Stjernegaard Jeppesen, T., Örn, A., Pape, T., Hobern, D., Garnett, S., Little, H., DeWalt, R. E., Miller, J., Orrell, T., Aalbu, R., Abbott, J., Abreu, C., Acero P, A., et al. (2026). Catalogue of Life (2026-08-26 XR). Catalogue of Life Foundation, Amsterdam, Netherlands. https://doi.org/10.48580/dgyy9