Lactuca canadensis
Sp. Pl. 2: 796. 1753.
Biennials, (15–)40–200(–450+) cm. Leaves on proximal 1/2–3/4 of each stem; blades of undivided cauline leaves oblong, obovate, or lanceolate to spatulate or lance-linear, margins entire or denticulate, midribs sometimes sparsely pilose. Heads in ± corymbiform to paniculiform arrays. Involucres 10–12+ mm. Phyllaries usually reflexed in fruit. Florets 15–20+; corollas bluish or yellowish, usually deliquescent. Cypselae: bodies brown (often mottled), ± flattened, elliptic, 5–6 mm, beaks ± filiform, 1–3 mm, faces 1(–3)-nerved; pappi white, 5–6 mm. 2n = 34.
Phenology: Flowering Jun–Oct.
Habitat: Roadsides, swamps, salt marshes, thickets
Elevation: 0–2200 m
Distribution
![V19-350-distribution-map.gif](/w/images/5/5a/V19-350-distribution-map.gif)
B.C., Man., N.B., N.S., Ont., P.E.I., Que., Yukon, Ala., Ariz., Ark., Calif., Colo., Conn., Del., D.C., Fla., Ga., Idaho, Ill., Ind., Iowa, Kans., Ky., La., Maine, Md., Mass., Mich., Minn., Miss., Mo., Mont., Nebr., Nev., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., S.C., S.Dak., Tenn., Tex., Utah, Vt., Va., Wash., W.Va., Wis., Wyo., Mexico, Central America, Eurasia.
Discussion
Selected References
None.