It is a late summer treat to see great blue lobelia in full bloom, often alongside the fabulously red cardinal flower. Sometimes called “blue cardinal flower”, great blue lobelia resembles red cardinal flower, (Lobelia cardinalis), in stature, habitat, and structure. Both of these plants are tall wetland species with colorful flowers borne on terminal racemes. Their tube-shaped flowers have a lower lip divided into three lobes and an upper lip divided into two lobes. The large leaves of great blue lobelia are alternate, lanceolate, serrate and sessile.
If left untouched, great blue lobelia will grow unbranched and reach up to 3 or 4 feet in height. However, if deer manage to browse them back, the flowers will be borne on shorter, branched racemes.
Great blue lobelia is not an edible plant. It is an emetic–meaning it will cause vomiting. Long ago it was thought to be medicinally useful as a cure for syphilis, hense the species name L. siphilitica.
Hummingbirds, insects and people are attracted to this beautiful flower. If you have a wet place in your yard, collect some seeds in early October and plant them right away for enjoyment next summer. Once started in the right place, the plants will self-sow.