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Great Blue Lobelia

Scientific name: Lobelia siphilitica

Lobelia siphilictica, also known as blue cardinal flower or great lobelia, is a native perennial. It typically grows in moist to wet soils along streams, swamps, meadows and in low wooded areas and reaches a height of 2-3 feet. It is a member of the Campanulaceae (“bellflower”) family which includes thousands of species of non-woody herbaceous plants many of which have blue, bell-like flowers.


Finely-toothed, lance-shaped light green leaves up to 5 inches in length.


This native perennial features blue tubular flowers in late summer. Each flower is split into two lips, the upper lip has two segments and the lower has three.

Blooming Season

Late summer.

Fun Facts

The Latin name of siphilitica arose from its use in the treatment of venereal disease.


This plant is found in locations with humus-rich, wet soils in full sun to part shade. Because it needs constant moisture, it will appreciate some shade. Great blue lobelia, cardinal flower and brook lobelia are wetland indicator plants, meaning that they only grow in wetlands.

Similar Species

There are two other species of Lobelia to be found locally. One is the Lobelia cardinalis (Cardinal flower) and the other is the Lobelia kalmii (Brook or Kalm’s lobelia). See photos below.

Human Connections

The beautiful blue blossoms in August make this a good choice for gardens with the right conditions.

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