Canada lettuce

(Lactuca canadensis)

Conservation Status
Canada lettuce
Photo by Alfredo Colon
  IUCN Red List

not listed

     
  NatureServe

N5? - Secure

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FACU - Facultative upland

     
  Midwest

FACU - Facultative upland

     
  Northcentral & Northeast

FACU - Facultative upland

     
           
 
Description
 
 

Canada lettuce is a 1 to 8 tall, erect. biennial forb with a thick, deep taproot. The stems and leaves contain a milky latex.

The stems are leafy, smooth, light green, and may have purple streaks.

The leaves are alternate, light gray-green to dark green, often with purple edges or a yellowish cast. They are up to 10 long and 3 wide. They are stemless, with the basal lobes partly surrounding the stem (clasping). They do not have prickles on the leaf margin. The midvein on the underside may have short, fine hairs, but not prickles.

The inflorescence is a tall, narrow, cone-shaped, loosely-branched cluster.

The flower heads are about across and have 13 to 22 ray florets.

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

 
     
 

Height

 
 

1 to 8

 
     
 

Flower Color

 
 

Pale yellow

 
     
 

Similar Species

 
 

Prickly lettuce (Lactuca serriola) has blue-green leaves with prickles on the leaf margins and on the underside of the midvein. The pale yellow rays in the flower heads have truncated tips with 5 small teeth.

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

Showy blue lettuce (Lactuca tatarica ssp. pulchella) has large, showy flower heads that measure, ¾ across.

Tall blue lettuce (Lactuca biennis) has bluish to white flowers. The achene has grayish-brown bristles attached to the tip.

Woodland lettuce (Lactuca floridana var. floridana) has light blue flowers.

 
     
 
Habitat
 
 

Moderate moisture. Fields, meadows, thickets, woods, waste places.

 
     
 
Ecology
 
 

Flowering

 
 

July to September

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

2, 3, 4, 5, 7, 24, 28, 30.

 
  3/16/2021      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

Common

 
         
 
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

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

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

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Lactuca canadensis var. integrifolia

Lactuca canadensis var. latifolia

Lactuca canadensis var. longifolia

Lactuca canadensis var. obovata

Lactuca canadensis var. typica

Lactuca sagittifolia

Lactuca steelei

 
       
 

Common Names

 
 

Canada lettuce

Canada wild lettuce

Canadian wild lettuce

Florida blue lettuce

tall lettuce

tall wild lettuce

wild 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.

 

Clasping

Describing a leaf that wholly or partly surrounds the stem but does not fuse at the base.

       
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Alfredo Colon
       
  Canada lettuce    
       
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  Wild Lettuce / Lactuca canadensis
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About

Published on Nov 28, 2013

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