Lobelia siphilitica

A blue beauty of the wetlands blooming in late summer

Lobelia siphilitica great blue lobelia

Plant grows in the wild/spontaneouslyPlant is cultivatedPlant is native to PA Add to MyPlants

This native perennial wildflower is one of the most beautiful of the late summer flowers.  It is the largest of the blue lobelias and produces a dense spike of 1-1 ½″ long tubular and lipped flowers. The plant grows from 1 to 4 feet high on a stem that is almost never branched. The flower spike’s height can vary from 6″ to 2 feet.

The deep blue flowers form in the axils of leafy bracts. They have 2 narrow lobes or 'ears' on top and three wider lobes below—the 'lip'. The corolla is in the form of a tube. Both the corolla tube and the lower lips are streaked with white. The calyx is hairy.

Great blue lobelia normally blooms in August and September. Bumblebees are the major pollinators. The oval or lance-shaped leaves are alternate and 2 to 6 in. long. This wildflower is cultivated in many wildflower gardens because it blooms for a long period of time.

Although the plant is a perennial, it is short-lived. Individual plants last only a few years. It does best with some shade at low woodland and in rich soil with a constant supply of moisture.

Contributed by: Mark Welchley

Frequent in swamps, moist meadows, stream banks, and ditches.

Present throughout the state.

Range: Found throughout eastern and central Canada and United States, except Florida. In the South populations are scattered except in the mountains.

Wetland codes
EMP: FACW
NCNE: FACW



Flowers August & September.

Inflorescence  crowded terminal raceme

Flowers  blue or occasionally white; on ascending pedicels growing from leaf axils; 2-lipped tubular corolla, lower lip has 3 lobes, upper lip 2 reduced lobes; calyx hairy

Leaves  simple, alternate; oblong or elliptic, sessile

Stems  erect, stout

Height  5 feet

S-rank:  S5 (Secure)
G-rank:  G5 (Secure)

Primary pollinators are bumblebees.  Even though most parts of the plant are toxic, deer may browse on this plant.

Lobelia siphilitica great blue lobelia

Plant grows in the wild/spontaneouslyPlant is cultivatedPlant is native to PA
Lobelia siphilitica gallery
Plant Life-Form
perennial forb
Common Names
great blue lobelia