blue lettuce

(Lactuca pulchella)

Conservation Status
blue lettuce
 
  IUCN Red List

not listed

     
  NatureServe

N4N5 - Apparently Secure to Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

UPL - Obligate upland

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FAC - Facultative

     
           
 
Description
 
 

Blue lettuce is a 1 to 4 tall, erect, perennial forb rising on usually a single stem from deep-seated, creeping roots. The stems and leaves contain a milky latex.

The stems are leafy and hairless.

The leaves are bluish-green, alternate, and unlobed or with narrow lobes. The underside of the leaves are often covered with a white, waxy bloom.

The inflorescence is several heads in a branched cluster.

The flower heads are about ¾ across and have 10 to 50, usually at least 15, ray florets.

The fruit is a reddish-brown achene with fluffy, white bristles attached to the tip.

 
     
 

Height

 
 

1 to 4

 
     
 

Flower Color

 
 

Blue to purple

 
     
 

Similar Species

 
 

This plant is easily distinguished from other lettuce species by its large, showy flowers.

Canada lettuce (Lactuca canadensis) has yellow flowers.

Prairie lettuce (Lactuca ludoviciana) has prickles along the leaf margins and on the midvein on the underside of the leaf.

Prickly lettuce (Lactuca serriola) has yellow flowers. The leaves have prickles on the leaf margins and on the underside of the midvein.

The blue species of Lactuca are extremely variable and identifying characteristics overlap, factors which, taken together, make the species difficult to separate.

Tall blue lettuce (Lactuca biennis) has smaller flower heads that are about ⅜ across. The achene has grayish-brown bristles attached to the tip.

Woodland lettuce (Lactuca floridana var. floridana) has smaller flower heads that are about across.

 
     
 
Habitat
 
 

Moist. Meadows, thickets, prairies.

 
     
 
Ecology
 
 

Flowering

 
 

June to September

 
     
 

Pests and Diseases

 
 

 

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 28, 29, 30.

 
  3/16/2023      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

 

 
         
 
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 (flowering plants)  
  Superorder Asteranae  
 

Order

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Cichorioideae (chicories, dandelions, and allies)  
  Tribe Cichorieae (lettuce, chicory, dandelion, and salsify)  
  Subtribe Lactucinae  
  Genus Lactuca (wild lettuces)  
       
 

Considerable disagreement continues about the proper scientific name for this plant. Six names are currently (3/16/2023) in use by widely respected authorities.

ITIS classifies it as Mulgedium oblongifolium;

The Plant List, FNA, NCBI, Minnesota DNR (MNTaxa), and Minnesota Biodiversity Atlas (Bell Herbarium) as Mulgedium pulchellum;

The Global Compositae Database, BONAP, and iNaturalist as Lactuca tatarica;

GRIN and Steyermark’s Flora of Missouri (Yatskievievyck, 2006) as Lactuca tatarica ssp. pulchella;

USDA PLANTS as Lactuca tatarica var. pulchella;

Plants of the World Online, World Flora Online, GBIF, iNaturalist, NatureServe, Manual of Vascular Plants (Gleason and Cronquist, 1992), and Flora of Minnesota (Chadde, Second Edition, 2019) as Lactuca pulchella.

 
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Lactuca oblongifolia

Lactuca tatarica

Lactuca tatarica ssp. pulchella

Lactuca tatarica var. heterophylla

Lactuca tatarica var. pulchella

Mulgedium oblongifolium

Mulgedium pulchellum

Sonchus tataricus

 
       
 

Common Names

 
 

biennial blue lettuce

blue lettuce

common blue lettuce

blue lettuce

Tartarian lettuce

wild blue lettuce

woodland lettuce

 

 

 

 

 

 

 

 

 

 

Glossary

Achene

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed entirely from the wall of the superior ovary, does not split open at maturity, but relies on decay or predation to release the contents.

 
 
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