Lobelia siphilitica (great blue lobelia)

University of Maryland Extension Recommended Native Plant

Great blue lobelia, a blue counterpart of the cardinal flower, is a very desirable addition to the woodland garden, blooming bright blue in late Summer. It grows anywhere from 2–4' tall in sun to part sun. It likes the wetter soils but can tolerate drier conditions better than the red cardinal flower. Lobelia siphilitica has blue-violet flowers that bloom in August and September. Good for perennial borders, wild gardens, naturalized, and water edges. The unfortunate species name is based on the fact that it was once a supposed cure for syphilis. All parts are poisonous and toxic only if eaten in large quantities.

Great blue lobelia is native to eastern and central Canada and the U.S. It thrives in moist to wet soils and partially shaded enviroments, including swamp forests, roadside ditches, floodplains, lake margins, and wet prairies. Attracts birds and hummingbirds, native bees and bumble bees, and supports conservation biological control by attracting insects that prey upon insect pests. Pollinated primarily by bumblebees, which use the lower three fused petals as a landing pad.

Photo by Kathy Thornton