Flower:

Elongating spike-like raceme of irregular tubular flowers about 1 inch long on a short flower stalk, with a leafy bract at base of the stalk. Color ranges from light blue to bright blue-violet. Flowers have 3 pointed lobes below and 2 smaller lobes above, sometimes erect but usually curved back. In between the upper lobes is a curved style. The lower center lobe has 2 small bumps near the throat, with a spot of white at the top of the bump, and white stripes on the outside of the throat. The calyx holding the flower has long narrow lobes, sometimes with long hairs around the edges. Leafy bracts become smaller as they ascend the stem. The cluster is typically densely packed at the top and a bit looser towards the bottom, with flowers blooming from the bottom up

Leaves and stem:

Leaves are 2 to 6 inches long and up to 2 inches wide, irregularly toothed, hairless or sparsely hairy, pointed at the tip, alternately attached with no leaf stalk. Shape is somewhat variable and may be elliptical, lance-like or only slightly narrowed toward the base. The stem is unbranched, ridged, and may have short hairs scattered along the ridges.

Fruit:

Fruit is a small 2-chambered capsule, each chamber containing many tiny, oval, semi-translucent golden brown seeds. Seeds are densely covered in a network of fine ridges and many shiny scale-like appendages, almost like shingles. The photo doesn't do them justice. :-)

Notes:

Blue Lobelia makes a great garden plant—butterflies love it. It is doing quite well in my own poorly drained clay soil in full sun, blooming most of the summer through early fall. The Lobelia genus was once in its own Lobeliaceae family, then was moved to the Campanulaceae (Bellflower) family but is now back in Lobeliaceae. There are 2 varieties, both found in Minnesota. Var. siphilitica is an eastern species where Minnesota is on the western edge of the range; it has leaves typically at least ¾ inch wide, 20 or more flowers in the cluster, and is hairy to varying degrees. Var. ludoviciana is a western species where Minnesota is on the eastern edge of the range; its leaves are less than ¾ inch wide, typically has 6 to 20 flowers, and is mostly hairless.