Lactuca in Manitoba - more puzzles :)



Lactuca biennis (Moench) Fernald - Tall Blue Lettuce

  • blue flowers, leaves irregularly pinnatifid, ; pappus brown, achenes nearly beakless2
  • biennial2
  • swampy or moist places; boreal forest 1

Lactuca canadensis Linnaeus - Canada Wild Lettuce

  • (MB ON QC NB PE NS) Vascan
  • yellow flowers
  • rare, boreal forest 1

Lactuca floridana (Linnaeus) Gaertner - Woodland Lettuce

  • (MB ON) Vascan
  • blue flowers
  • leaves petiolate, toothed and often also pinnatifid, pubescent on the underside of the main veins; pappus white 1
  • margins of woods, boreal forest1
  • rarely observed

Lactuca ludoviciana (Nuttall) Riddell - Western Lettuce

  • (SK MB) Vascan
  • yellow or blue flowers, leaves mostly pinnatifid, spinulose margined and more or less prickly on the mid-rib beneath and strongly glaucous, pappus white, achenes distinct soft filiform beak, 2
  • along riverbanks, parklands1
  • rarely observed


Lactuca serriola Linnaeus - Prickly Lettuce

  • Vascan
  • yellow flowers
  • leaves copiously spinulose-denticulate, spinulose bristly on mid rib underneath and tending to turn with one edge up2
  • very common; roadsides, slough margins, waste places, cultivated land; throughout Prairie provinces1
  • previously known as Lactuca scariola



Mulgedium pulchellum (Pursh) G. Don - Blue Lettuce

  • (BC AB SK MB ON QC) Vascan
  • blue flowers
  • leaves entire, lower leaves may be more or less lobed; pappus white, achenes with short firm beak2
  • perennial2
  • common...cultivated lands and roadsides, throughout Prairie provinces1
  • previously known as Lactuca pulchella or Lactuca tatarica var pulchella

What I am going to try out

looks like habitat, flower color / number and leaves are the most helpful things - with a nod to the color of the pappus - that is the fluffy stuff attached to the seed to help it drift on the wind.

the prickly ones...

  • if the plant is in proximity to human disturbance and the flower is yellow and the leaves are turned to be perpendicular to the ground- edge to the sky >>> Lactuca serriola
  • if the plant is along a river (or other damp to wet ground) and the flowers are yellow or blue >>> Lactuca ludoviciana (L ludoviciana tends to have more flowerheads (12-20) over L serriola (5-12))

the non-prickly ones....

  • if the flowers are blue and the pappus is white and the upper leaves are entire and the plant is commonly seen >>> Mulgedium pulchellum / Lactuca pulchella (two names for the same plant)
  • if the flowers are blue and the pappus is brown and the leaves are pinnatifid and the plant is in a wet spot in the boreal>>> Lactuca biennis (especially if the plant is 2 meters or taller)
  • if the flowers are blue and the pappus is white and the leaves are pinnatifid and the plant is at a forest edge in the boreal>>> Lactuca floridana
  • if the flowers are yellow >>>Lactuca canadensis


  1. Budd, A.C.; Looman, J., Best, K.F., Budd's Flora of the Canadian Prairie Provinces, 1979 Ottawa
  2. Scoggan, H.J, Flora of Manitoba, 1957 Ottawa
Posted by marykrieger marykrieger, August 16, 2021 14:45


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