Canada lettuce

(Lactuca canadensis)

               
Conservation Status

IUCN Red List

not yet assessed

Canada lettuce

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

Nativity

Native

Occurrence

 

Habitat

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

Flowering

July to September

     
Flower Color

Pale yellow

     
Height

1 to 8

     

Identification

This 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.

 
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.


Distribution Distribution Map   Sources: 2, 3, 4, 5, 7, 28.

Comments

 


Taxonomy

Family:

Asteraceae (aster)

 

Subfamily:

Cichorioideae

 

Tribe:

Cichorieae

 

Subtribe:

Lactucinae

 
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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About

Published on Nov 28, 2013

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