tall blue lettuce

(Lactuca biennis)

Conservation Status
tall blue lettuce
Photo by Alfredo Colon
  IUCN Red List

not listed


NNR - Unranked

SNR - Unranked


not listed

Wetland Indicator Status
  Great Plains

FAC - Facultative


FAC - Facultative

  Northcentral & Northeast

FAC - Facultative


Tall blue lettuce is a 2 to 6½ tall, erect, annual or biennial forb with a thick, deep taproot. The stems and leaves contain a milky latex.

The stems are leafy and hairless.

The alternate leaves are lobed halfway or more to the midrib but not reaching the midrib. They are up to 4 to 16 long and 1½ to 8 wide. They are attached to the stem without a leaf stalk, with the base partly surrounding the stem (clasping). The main veins on the underside are hairy.

The inflorescence is a terminal tall, narrow, crowded cluster, and small clusters in the leaf axils.

The flower heads are about across and have 15 to 50, usually 20 to 30, bluish to white ray florets.

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




2 to 6½


Flower Color


Bluish to white


Similar Species


Canada lettuce (Lactuca canadensis) has yellow flowers.

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

Blue lettuce (Lactuca pulchella) has large, showy flower heads that measure, ¾ across. The achene has white bristles attached to the tip.

Woodland lettuce (Lactuca floridana var. floridana) has a more open inflorescence and tends to be less leafy than tall blue lettuce. The flower heads have 10 to 15 ray florets. The achene has white bristles attached to the tip.


Moist. Thickets, stream banks, woods.




July to September


Pests and Diseases






Distribution Map



2, 3, 4, 5, 7, 24, 28, 29, 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)  


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)  

Subordinate Taxa






Lactuca spicata

Lactuca spicata var. integrifolia

Mulgedium spicatum

Mulgedium spicatum var. integrifolium

Sonchus biennis


Common Names


biennial blue lettuce

biennial lettuce

tall blue lettuce

wild blue lettuce

wild lettuce

woodland lettuce













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.



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

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Alfredo Colon

    tall blue lettuce   tall blue lettuce  
MinnesotaSeasons.com Photos
    tall blue lettuce   tall blue lettuce  






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  Alfredo Colon

Location: Albany, NY

tall blue lettuce  
  Alfredo Colon

Location: Albany, NY

tall blue lettuce  
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