Lactuca virosa
Lactuca biennis
bitter lettuce, great lettuce, poison wild lettuce, tall lettuce, wild lettuce
biennial wild lettuce, tall blue lettuce, wild blue lettuce
on proximal 1/2–2/3 of each stem;
blades of undivided cauline leaves obovate to spatulate, margins denticulate, midribs usually prickly-setose.
on proximal 2/3–3/4 of each stem;
blades of undivided cauline leaves ovate to lanceolate, margins entire or denticulate, midribs sometimes sparsely piloso-setose.
12–15 mm.
7–12+ mm.
10–15;
corollas yellow, usually deliquescent.
(15–)20–30(–50+);
corollas bluish or whitish, sometimes yellowish, seldom deliquescent.
usually reflexed in fruit.
usually reflexed in fruit.
in paniculiform arrays.
in paniculiform arrays.
bodies purplish to blackish, ± flattened, ± elliptic, 3.5–4 mm, beaks ± filiform, 2.5–3.5 mm, faces 5–7-nerved;
pappi white, 5–6 mm.
bodies brown (often mottled), ± compressed-ellipsoid, 4–5+ mm, beaks ± stout, 0.1–0.5+ mm, faces (4–)5–6-nerved;
pappi ± fuscous, 4–6+ mm.
= 18.
= 34.
Lactuca virosa
Lactuca biennis
The type of Lactuca terrae-novae Fernald is probably conspecific with that of L. biennis. The type of L. biennis may be conspecific with that of L. floridana.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
- Local floras:
BC, 
CA, 
OR, 
WA - Local Web sites: CalFlora, CalPhotos,
Flora NW, 
Go Botany, 
IL Wildflowers, 
MD Biodiversity, 
MI Flora, 
MN Wildflowers, 
PNW Herbaria 
WildflowerSearch
iNaturalist (observations)
USDA Plants Database- LBJ Wildflower Center
- SEINet
- Plants of the World Online
- Encyclopedia of Life
- Wikipedia
- Google Image Search
