Lactuca virosa
Lactuca serriola
bitter lettuce, great lettuce, poison wild lettuce, tall lettuce, wild lettuce
prickly 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 1/2–3/4 of each stem;
blades of undivided cauline leaves usually ± oblong, sometimes obovate to lanceolate, margins denticulate, usually prickly, midribs usually prickly-setose, rarely smooth.
12–15 mm.
9–10(–12) mm.
10–15;
corollas yellow, usually deliquescent.
12–20;
corollas yellow, usually 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 pale grayish to tan, ± flattened, oblanceolate, 2.5–3.5 mm, beaks ± filiform, 2.5–4 mm, faces (3–)5–9-nerved;
pappi white, (3–)4–5 mm.
= 18.
= 18.
Lactuca virosa
Lactuca serriola
The name Lactuca scariola Linnaeus is evidently illegitimate; it is a superfluous name based on the same type as L. serriola. Plants included here in L. serriola with most leaf blades obovate to lanceolate (not lobed) and lacking prickles on midribs have been called L. scariola subsp. or var. integrata or L. serriola forma integrifolia or L. serriola var. integrata.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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