western Jacob’s ladder

(Polemonium occidentale ssp. lacustre)

Conservation Status
western Jacob’s ladder
Photo by Katy Chayka
  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

S1 - Critically Imperiled

     
  Minnesota

Endangered

     
           
Wetland Indicator Status
     
  Great Plains

FACW - Facultative wetland

     
  Midwest

FACW - Facultative wetland

     
  Northcentral & Northeast

FACW - Facultative wetland

     
           
 
Description
 
 

Western Jacob’s ladder is an erect, perennial, up to 40 tall forb that rises on a single stem from the upturned end of a short, slender, unbranched, horizontal, underground stem (rhizome).

The leaves are alternate. Lower leaves are pinnately divided into up to 27 narrow leaflets. The leaflets are lance-shaped, to 1½ long, and stalkless or almost stalkless. The margins are untoothed. The leaves get smaller and less divided as they ascend the stem. The leaf subtending the flowering stalk has 9 to 13 leaflets.

The inflorescence is a crowded, elongated, somewhat cylinder-shaped or egg-shaped, branched array (panicle) of several small clusters of flowers.

The flowers are bell-shaped and to long and wide. They are on 3 16 to ¼ long stalks, the stalks at least as long as the sepals. There are 5 sepals, 5 petals, 5 stamens, and 1 style. The sepals are green and form a bell-shaped structure (calyx) that is longer than the stalk of the flower. The petals are mostly blue but white at the base. They are joined at the base into a corolla tube then separated at the tip into 5 broadly triangular, widely spreading lobes that are longer than the tube. The stamens are as long as, or a little shorter than, the corolla. The anthers are white. The style is conspicuously longer than the stamens.

The fruit is a egg-shaped to round, 3-chambered, to long capsule with 1 to 10 seeds per chamber.

 
     
 

Height

 
 

Up to 40 tall

 
     
 

Flower Color

 
 

Blue

 
     
 

Similar Species

 
  Charity (Polemonium caeruleum) is a garden plant that sometimes escapes cultivation. The leaf subtending the flowering stalk has only 3 to 7 leaflets. The corolla is purple to flesh-pink, not blue. The capsule is larger, ¼ to 5 16 long.  
     
 
Habitat
 
 

Wet. Openings in conifer swamps with a blanket of sphagnum and other mosses and dominated by northern white cedar and sometimes tamarack and/or black spruce. Full or partial sun.

 
     
 
Biology
 
 

Flowering

 
 

Late June to July

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 24, 28, 30.

There are only six known populations of this plant, two in Wisconsin and four in Minnesota. All of the Minnesota sightings were in conifer swamps that been selectively logged. Three of the Minnesota populations are within 50 miles of each other in St. Louis County. One of those was found in 1944 but has never been found again. The fourth is in a conifer swamp in southeastern Itasca county.

The dark green counties on the map at left include locations verified by the Minnesota DNR and/or the Bell Herbarium. The light green county indicates one location in Clay County listed by BONAP. iNaturalist lists a sighting at the Minnesota Landscape Arboretum in Carver County. Arboretum sightings are not included on distribution maps.

 
  3/31/2021    
       
       
       
       
       
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Rare

 
         
 
Taxonomy
 
  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 (dicots)  
  Superorder Asteranae  
 

Order

Ericales (heathers, balsams, primroses, and allies)  
 

Family

Polemoniaceae (phlox)  
  Subfamily Polemonioideae  
 

Genus

Polemonium (Jacob’s ladder)  
  Species    
       
 

Subordinate Taxa

 
       
       
 

Synonyms

 
  Polemonium occidentale var. lacustre  
       
 

Common Names

 
 

western Jacob’s ladder

western Jacob’s-ladder

western polemonium

 
       

 

 

 

 

 

 

 

 

Glossary

Corolla

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

 

Panicle

A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.

 

Pinnate

Having the leaflets of a compound leaf arranged on opposite sides of a common stalk.

 

Rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

Sepal

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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

       
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Katy Chayka
       
  western Jacob’s ladder    
       
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Katy Chayka
2/26/2015

Location: Itasca County

western Jacob’s ladder


     
     
 
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