great blue lobelia

(Lobelia siphilitica var. ludoviciana)

Conservation Status
great blue lobelia (var. ludoviciana)
  IUCN Red List

not listed


NNR - Unranked

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

OBL - Obligate wetland


OBL - Obligate wetland

  Northcentral & Northeast

FACW - Facultative wetland


Great blue lobelia (var. ludoviciana) is a 12 to 48 tall, erect or strongly ascending, perennial forb that rises from a taproot.

The stems are erect, stout, leafy, and angular, at least near the top. They are usually unbranched, sometimes there are a few branches toward the top. They are mostly hairless but may be sparsely covered with short hairs on the angles.

The leaves are alternate, thin, lance-shaped to elliptic or inversely lance-shaped, ¾ to 6 long, and ¾ to 2 wide. They taper to a point at the tip and are tapered or angled at the base. They are stalkless or on short leaf stalks. The upper and lower surfaces are hairless. The margins are finely, irregularly toothed.

The inflorescence is a spike-like, unbranched, elongated, 4 to 12 long cluster of usually 6 to 20 flowers at the end of the stem. The flowers are on ascending, hairless, to 5 16 long stalks. The stalks have a pair of bracts at or above the middle and a pair of minute bracteoles at the base of or just below the calyx. The bracts are leaf-like in the lower part of the inflorescence, gradually becoming smaller as they ascend the stem.

The flowers are to 1¼ long and about ½ wide. At the base there are 5 are lance-shaped, hairless, 5 16 to 11 16 long sepals that are fused at their base into a bell-shaped, 1 16 to long tube, then separated into 5 slender, ¼ to 9 16 long lobes. At the base of each lobe of the calyx is a pair of long, conspicuous projections (auricles).

There are 5 blue to bluish-purple petals fused at their base into a 7 16 to ¾ long corolla tube, then separated into an upper and lower lip with spreading, 3 16 to ½ long lobes. The tube has slit-like openings and is sometimes striped with white. The lower lip is large with 3 lobes, the upper lip is smaller and split nearly to the base into 2 spreading lobes. There are 5 stamens. The filaments are fused from just above the base into a ½ to long tube surrounding the style. The anthers are fused into a to 3 16 long ring around the style. The style and filament tube protrudes from between the 2 lobes of the upper lip and bends downward near the tip. The flowers are not fragrant.

The fruit is a yellowish-brown, 3 16 to long capsule, ellipse-shaped lengthwise, round in cross section.




12 to 48


Flower Color


Blue to bluish-purple


Similar Species


Great blue lobelia (Lobelia siphilitica var. siphilitica), the eastern variety of this species, has hairy leaves that are mostly more than ¾ wide. The inflorescence has 20 to 60 flowers. The flower stalks and calyces are hairy. Minnesota lies where the ranges of these two varieties meet. The plant characteristics that identify each variety intergrade in this area and the varieties may not always be distinguishable (or even valid).


Wet to moist. Meadows, streambanks, river banks, bottomland forests, edges of lakes and ponds, swamps, fens, roadsides. Full sun.




August to September


Pests and Diseases






Distribution Map



4, 7, 28, 30.









  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Campanulaceae (bellflower)  
  Subfamily Lobelioideae (lobelia)  


Lobelia (lobelias)  
  Section Lobelia (typical lobelias)  
  Species Lobelia siphilitica (great blue lobelia)  

Subordinate Taxa








Common Names


blue cardinal-flower

blue lobelia

great blue lobelia

great lobelia













A small, ear-like projection at the base of a leaf or at the junction of a grass blade and stem.



Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.



A small, often secondary bract within an inflorescence; a bract that is borne on a petiole instead of subtending it; bractlet.



The group of outer floral leaves (sepals) below the petals, occasionally forming a tube.



A collective name for all of the petals of a flower.



An outer floral leaf, usually green but sometimes colored, at the base of a flower.

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    great blue lobelia (var. ludoviciana)   great blue lobelia (var. ludoviciana)  






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